FOUNDATION FOR ALTERNATIVE ENERGY - SLOVAKIA
Emil Bedi
1 9 9 5
Foundation for Alternative Energy, Slovakia
C O N T E N T S :
Many NGOs from Central and Eastern Europe (CEE), working on energy issues, are trying to develop alternative energy policy which could reflect the ideas of sustainable development and which could give solutions to the threat of global climate change and other environmental problems as well. This attempts are in CEE urgently needed , because nearly all governments in the region are building their energy policy on pollution-rich fossil fuel combustion and nuclear power. Most of the NGOs in the region has soon recognized that it is not enough just to say 'no' to particular subject , but that they could achieve much more if they force their own energy policy option. Building bricks of the new NGO energy strategy has been declared in various documents like Celakovice statement (1) or Greenway Energy Group meeting in Bratislava (2).
Due to the democratization process of the society in CEE we live at a time when NGOs are more able than ever to affect their political representatives. Active lobbying of some NGOs for energy savings and renewables has led to the point where NGO representatives became the partner for governmental organizations and are involved in continual dialog on energy policy orientation. Some decision-makers accepted this new way of thinking and are ready to implement at least principles of energy efficiency into official policy. Transformation process in CEE towards market economy brings new opportunities in this area. But declining gross domestic product (GDP) and the lack of domestic financial resources created the barrier which is too high for most of the countries in the region to realize the sustainable option.
Foreign investors supported by large Western banks with their attempts to revitalize the nuclear power in CEE , undermine this process of change. CEE NGOs are facing the new challenge - they have to fight against much stronger opposition than decaying domestic utilities. The new incentives which could strengthen their standpoints are required.
This publications is intended to review the problems of energy utilization and gives the basic options we have towards sustainable energy path.
OUR UNSUSTAINABLE PRESENT
There is no life without energy. Everybody knows that fossil fuels are finite and that their use is damaging our natural environment including human health and imbalancing the Earth's climate.But still more nuclear, coal, and other fossil fuel fired power stations are being built around the world despite the fact that huge amount of this energy is wasted and that utilisation of clean renewable sources is blocked by 'market forces', political shortseeing, and the pressure of fossil fuel lobby groups. The way we are consuming energy at present is simply unsustainable . Let take a look on some basic facts, barriers and possible solutions towards sustainable energy age.
MORAL OF BUSINESS AS USUAL PHILOSOPHY
THE FACT : The days of non-renewable sources of energy are counted within the ridiculously short span few generations.
QUESTION : Who gave us the right to change these resources to waste and pollution? Who is speaking for the next generations?
ANSWER: At present these questions simply do not fit to business as usual pattern and thus they are effectively blocked by lobby groups and politicians. In simplified way it can be said that not moral but money is the driving force of our development.
RENEWABLES INSTEAD OF FOSSIL FUELS
FACT : The renewable energy sources can provide us with all our energy needs.
QUESTION : If it is so are the market and political forces the only reason why they cover only a tiny fraction of our consumption in Europe (few percentage) and their share is nearly negligible in CEE ?
ANSWER: There are of also some practical reasons which make that making money with fossil fuel production and utilisation is much easier than with renewable energy sources. This situation can be seen from the following comparison.
Energy Source Energy Density
kW/m2
Biomass production 0,0002
Solar irradiation (CEE) 0,1
Wind energy 3
Coal (boiler, power plant) 500
Nuclear energy (fuel rod) 650
ENERGY COST
QUESTION: Does all this mean that using renewables is more expensive for the society than burning fossil fuels?
ANSWER: If we are looking only at present energy prices (electricity, heat, gasoline) most of renewables seems to be more expensive at the first sight. But the price we are paying for energy now does not express the true (total) costs of fossil fuel production and utilisation. There are huge costs which are hidden or are imposed on members of society other than the producers and users of the energy that causes the costs. Because general market pricing mechanisms does not work adequately these costs which include environmental damage to flora, fauna, human health or materials, cultural heritage should be included in total 'internalise' energy costs. For example waste problems (e.g. radiactive) connected to utilisation of fossil fuels are simply (and arrogantly) shifted to the next generations. Unfortunately only a fraction of these costs can be expressed in monetized way. The major part of these costs is not yet quantified or even identified (like global climate change). One of such an expression of external costs can be seen from the following table:
Estimated external costs of air pollution for different type of damage in Germany (3)
DAMAGE TO DAMAGE IN MILLION DM/YEAR Human Health 2 300 - 5 800 Materials 2 300 Fauna 1 000 Flora 6 500 - 9 800 TOTAL 11 200 - 18 000
CONCLUSION: polluting the environment by utilisation of fossil fuels is practically free and thus makes most of renewable energy sources uncompetitive. Including external cost into the price of energy, what means rising the prices, is politically not attractive because the political will to make a change is mostly framed by election periods leaving the long term problems untouched.
There are several examples like unsuccessful battle for CO2/energy tax in EU which clearly shows shortsighting of present energy policy in nearly all parts of the world. This way is also supported by big financial institutions including the World Bank and EBRD which are still pouring much bigger amounts of money to fossil fuel and nuclear industry instead of energy efficiency and renewable energy oriented projects. This is simply the challenge for NGOs which can not be omitted yet when more and more environmental threats became a reality.
SOCIAL BENEFITS OF SUSTAINABLE ENERGY PATH
FACT :
It is often forgotten that utilisation of renewable energy sources and realisation of projects towards increasing energy efficiency have positive impact on social development especially on job creation. This way is more beneficial for the society than utilisation of fossil fuels , see the next table .
NEW JOBS
Wood combustion 450 jobs/TWh/year
(mainly in forest sector)
Straw combustion 200 jobs/TWh/year
(mainly in agriculture)
Solar thermal electricity 248 jobs/TWh/year
product..
Biogas total 560 jobs/TWh/year
(420 jobs/TWh for operating and maintenance)
Energy efficiency 360 jobs/TWh saved
Fossil cogeneration plant 250 jobs/TWh
(100 jobs/TWh construction + 150 jobs/TWh OM
Fossil energy sector 150 jobs/TWh/year
electricity generation
EXAMPLE
In Brazil 12 mil. m3 of ethanol as a substitution of gasoline for cars is produced per year from sugar cane. This activity has created 450.000 permanent jobs, 100.000 temporary jobs and 1,8 mil. indirect jobs in related industries.
TOWARDS SUSTAINABLE ENERGY AGE
FACT :
Investments in the energy sector are some of the largest and most long-term investments in the industrialised world. Energy investments are often larger than the total industrial investments in a country, and they have great influence on development of society and environmental pollution. Decisions in the energy sector determine the structure in the far future; e.g. we have to live with power plants for more than 25 years and with the radioactive waste for more than several hundred thousands years.
Role of NGOs:
It is important that many groups participate in energy planning, so it is based on the widest range of experience, and that most of us in this field take part in forming our common future.
This section describes some important elements in energy planning. There are of course differences between energy planning at municipal or community level, and national planning. A part of the described planning procedure is easiest to carry out at national level, but with a good will and a little creativity nearly everything may be implemented locally.
Objectives
During the last years security of supply, cheapest possible energy supply, have been in focus as the main goals of energy planning. Among other important objectives can be mentioned decreasing import. Some energy planners have other goals, e.g. securing the cheapest possible energy supply to industry, protection of capital interests of specific energy companies, or protection of specific markets for energy and energy technology.
Lately the abundant energy supply has caused that security of supply has receded into the background in Western Europe. The main conflicts are now between the desire for cheap energy, environmental considerations, and the interests of the energy utilities. A good energy plan can provide cheaper and at the same time more environmentally compatible energy supply than the present. But all parts of the planning process need political choices, non-political planning does not exist.
The objective of energy planning should not be to provide energy, but energy services. We do not need electricity or gas. We need light, heat in our houses, heat for industrial processes, and so on. This difference is important, as it is often cheaper and less environmentally harmful to increase energy efficiency at demand side (insulate houses, control industrial processes better, etc.), than to invest in the equivalent energy production.
Physical value of energy
It is important to keep in mind that different forms of energy have different values, when energy systems are planned. The more other states one form of energy can be converted into without loss, the higher value it has. Electricity and kinetic energy have the highest value, next come gas, oil, coal, biomass, and other fuels, and at the bottom heat. The higher temperature of heat, the higher is its value.
In practice this means that if gas, coal, or biomass is converted into electricity, there will be good 50% loss (in CEE up to 70%), which becomes heat. This heat can be used for residential heating or in industry. Often industrial processes have a surplus of heat at a lower temperature than needed in the process. This heat can be used for residential heating. An essential element in energy planning is to make use of this connection between the different energy forms.
Modern Energy Planning which should be supported by NGOs consists of:
Energy service consumption
The cornerstone is an estimation of the existing energy service level, which is based on knowledge of residential, commercial and industrial space, industrial production, and so on. From this is made one or more forecasts of the development during the coming decades. The forecasts shall be based on expected development, and the human needs that have to be fulfilled. They should not transfer political desire of economical growth directly to growth in energy services.Nowadays it is cheaper to expand energy systems later on, than to construct large plants from the beginning, therefore it is important not to over-estimate the future energy service level.
Demand-side technology
Energy consuming technologies transform energy into demanded energy services. There are big differences between how efficient this is done, and there are huge possibilities to improve efficiency. There are many options for influencing the efficiency:
Energy planning must be based on evaluation of existing demand-side technology efficiency, evaluation of the expected market development without planning, and evaluation of expenses and savings of different actions that influence demand-side efficiency. These evaluations create a survey of options to influence the energy consumption by energy planning, without affecting the energy service level.
Supply technology
The technologies to utilise different energy sources must be evaluated. This both counts for the existing technologies and their distribution, as well as possible improvements, new technologies, and likely development without planning. Supply technologies must utilise the resources as efficient as possible; e.g. heat from power plants and industry must be used for district heating, energy must be transported with as little loss as possible, and as little as possible.
With supply technology always goes the question, which scale to choose. Pure technical the question can be asked: what is most effective and cheapest, centralised energy supply with long transmission lines to the consumers or decentralised supply with more local supply units? For a long time the development has headed toward more centralised plants, but during the last decade both economy and efficiency have drastically improved for the smaller units compared to the centralised solutions. In that way the technical arguments for centralised solutions still get less.
Centralised vs. decentralised solutions is not only a question of technology. There is a good part of power concentrated around centralised energy supply systems. Therefore the energy utilities may be interested in centralised solutions, to gain or keep power over the energy systems.
An essential question concerning energy supply technologies is, how is it owned: public owned, owned by consumers, or commercial. All 3 types can be centrally or decently organised ownership's. It is essential for an energy plan that the owners are interested in following the plan, and that they can not hinder parts of the plan through their influence.
Integrated resource planning
In USA some states have introduced an efficient, modern planning method, primarily in the electricity sector. It is integrated resource planning, also called least cost planning.
The method is to set up all possibilities for supply, and for control and rationalisation of consumption (demand-side management), and then choose the socio-economically cheapest solutions. In USA the system works in a system with private power utilities having monopoly in certain areas. On the other hand the utilities are controlled by Public Utility Commissions.
The method has already led to considerable savings in e.g. California, and a study forecasts that it will reduce USA's electricity consumption with 20% by year 2010 (4).
Integrated resource planning is based on three fundamental principles:
The transport sector is the sector with the fastest growth in environmental pollution, e.g. CO2-emission. While primary energy consumption is expected to be constant or declining in the future, then the official transport policies expects increasing energy consumption for transport and increasing emission of some pollutants.
Options in the cities
The worst local environmental problems due to traffic exist in the cities. Here at least 80% of air pollution at street level comes from traffic pollution, and nearly half of the dwellings are bothered by noise. It is also in the cities there are most options to reduce energy consuption and the harmful traffic effects.
Most important is to move passengers from cars to public transport and bikes. If public transport is faster and cheaper than motoring, then most people will choose public transport. Improvements in public transport are, e.g. additional and faster rail lines and busses, as far as possible with separate bus lanes. Improvements for bikers include bike lanes at all busy roads, and bike routes through the cities. Motoring in cities can be made more expensive by parking toll, and toll on driving into or through city areas. This kind of taxation does not make it more expensive to drive cars outside cities, where good public transport systems do not exist.
Urban planning is the other important element in reducing energy consumption and harmful effects due to city transport. The planning should reduce the transport demand as much as possible, and allow everybody to use public transport and bikes.
The plans should ensure that it is possible for everybody to live in biking distance form their job. Dwellings should be placed within biking distance from a station, and large shopping centres and workplaces within walking distance.
It is important to know that it is possible to reduce environmental impact from traffic that much, just by changing the price relation between individual and public transport, and invest the profit in public transport. Unfortunately the proposals like this have strong opposition from the car and asphalt business that feel their markets threatened. As long as power belong to these groups that kind of proposals will barely come through.
Options for longer distances
For long-distance passenger transport trains must be given higher priority than cars and planes, if there is a wish to reduce energy consumption and environmental pollution arising from this sector. Like in the cities, price, speed, and comfort are decisive, when choosing means of transport. Especially international train transport needs to be improved. Today there are good possibilities to make fast trains competitive to cars and planes on distances shorter than 500 km.
Besides it shall be considered to halt growth in transport. E.g. environmental tax could be introduced on holiday trips, with tax-rate related to travel distance.
About goods higher priority must be given to train and ship, than to lorry and plane. Also goods transport is chosen by price and speed, plus guaranteed delivery in time. At rail it is about introducing more efficient goods transport, e.g. by reducing the time consuming shunt switching, and establishing terminals where goods can be reloaded quickly between road and rail.
It is important that lorries pay for their real environmental costs and road wear; today they only pay part of the expenses. Part of the expected growth in environmental pollution from traffic, is due to foreseen increased goods transport, e.g. caused by the EU internal market. But we would not get this growth in goods at all, if the transport price raised, e.g. to the real price inclusive environmental costs. Then local production will be more profitable than long-distance transport. Unfortunately the above mentioned car lobby until now succeeded in having higher priority given to motorways and bridges, than to public transport.
A new transport policy is needed
As mentioned, a totally new transport policy is needed, if we want to solve the energy and environmental problems related to transport. Today there are a row of obstacles to get a reduction of energy consumption and environmental pollution in the transport sector.
In the following are mentioned some of the barriers and possible solutions
TECHNOLOGY OPTIONS
We don't need all the energy we consume today. Considerable energy savings can be achieved both in households and the commercial sector, if we use the most efficient energy technologies existing today and change our consumer behaviour. The more energy we save, the easier it will be to cover the remaining consumption by renewable sources.
When working on increasing domestic energy consumption, it is important to look at the total energy consumption of the house, related to different initiatives. For example installation of mechanical ventilation with heat recovery causes a fall in heat consumption, but at the same time is introduced extra consumption of electricity, which is produced at lower efficiency than the heat (unless there is electric heating). Likewise will replacement with more efficient electrical devices cause a fall in free heat supplement. Some people use this as an argument against increasing electricity efficiency, but often the reality is that the heat cannot be used, and electricity is an inefficient heat source (at coal-fired power plants the efficiency is only 30-40%).
Low energy building
The house functions as a climate shelter, which we use to maintain a comfortable climate for ourselves, regardless of the surrounding natures behaviour. Sometimes it is too hot, other times it is too cold. The natural conditions that have an influence on energy consumption related to heating or cooling are temperature, humidity, wind speed, and solar irradiation. In our climate it is mainly a problem to maintain a convenient temperature during the winter.
An important principle of low energy building is adaptation to the surrounding nature. Often we can get inspired by traditional local building, which has evolved through many years experience with the actual climate. To be characterised as a low energy building, it is pure technically required that the buildings heat consumption does not exceed 50% of the consumption of a building complying with the building code. Some concrete instructions to be followed for low energy building are:
1. Choose simple solutions.
2. Place only windows, where positive heat balance can be achieved.
3. See to efficient insulation without thermal bridges.
4. Consider tightness and fresh air supply.
5. Build glass rooms that decrease surface area of the building.
6. Locate living rooms at the sunny side.
7. See to efficient regulation of central heating installations.
8. Use solar heaters and solar walls as solar heat contribution.
9. Minimise electricity consumption by choosing high efficient electric devices.
10.Use materials with low energy consumption for manufacturing and transport.
USEFUL TIPS:
Building Shape
Homes should be build compact and well-insulated. The energy consumption is very dependent on the surface area and shape of the building. For example a roof with high pitch deflects the wind, and reduce the effect of the cold winter winds.
Especially during winter the building should be sheltered from cold winds. If the predominant wind directions are north and west and the ground is south sloping, the house can be build into the slope. Soil is a good insulator, and the hill function as a windbreak. There can also be build banks of earth at the northern side of the house. Another option is to establish wind breaking banks close to the house, or plant evergreen trees as wind mantle. Also a fence, garages, and sheds function as windbreaks.
Interior Design
The home should be organised with primary living rooms (sitting room, kitchen-dining room) to the south, where the sun provides light and heat. This way they are also placed farthest away from the cold winter winds. In the centre or to the north are located the secondary living rooms (sleeping rooms), that only are heated occasionally. Non-living rooms like scullery, workshop and garage are located to the north. In this way they are insulating the heated part of the house.
By locating non-heated and secondary rooms to the north, energy consumption for heating is reduced. Chimneys from heating installations should be located in the centre of the house, to utilise heat from the smoke as good as possible. A chimney along the outer wall is to heat for the birds. There should be a windbreak or weather porch at the entrance to reduce heat loss. The entrance can profitably be placed lower than living rooms, as the cold air stays down.
Insulation
Huge savings can be obtained by insulating old houses (what is of special importance in CEE where inefficient buildings are quite common), and it must be a matter of course to construct new houses with efficient insulation.
It is however not only insulation depth that counts. Also hot water consumption, ventilation loss, regulation, and user behaviour influence the total heat consumption. Overheating of rooms is also a common problem in CEE and the higher efficiency should be forced where it is possible.
HAND RULE
For each degree the temperature is lowered about 6% of the energy consumption is saved. 20°C is sufficient in living rooms, and unused rooms should not be heated.
Heat consumption can be halved by insulation of a non-insulated house. The saving is achieved by insulating roof, floors, and walls with 100 mm mineral wool, the windows are changed from one layer of glass till two layers, and the house is tightened everywhere. At the same time halving of the hot water consumption is expected due to better behaviour and use of water saving devices .
All radiators should be thermostatically controlled, to ensure a comfortable, but not too high temperature. At the same time can perhaps be installed clock-timers that turn off the circulation pump at night, or automatically lowering of night temperature. However, the latter is unnecessary, if one remembers to turn off the heat. Blocks of flats and other homes with collective heat supply ought to have individual metering of the heat consumption, as it encourage energy savings.
Insulation of Existing Buildings
The heat consumption is often large in older buildings that are poorly insulated and untight. Afterinsulation will under most circumstances give a higher comfort in addition to lower energy consumption. Problems with draught are rectified, partly because the building often gets tighter, partly because the inner walls get warmer. When draught is avoided, it is possible to lower the room temperature, and at the same time keep up the comfort level, in this way extra energy is saved.
USEFUL TIPS:
Walls
Solid walls can be insulated either at the inside or at the outside. The two methods have different benefits and disadvantages. Outside insulation covers the total wall surface including horizontal divisions, by which thermal bridges are avoided. On the other hand is the front totally changed. Outside insulation is often more expensive than inside, but it is profitable if the front is going to be renovated anyway. It is easier to insulate inside, and it can be done as going along. On the other hand, it is a disadvantage in small flats that the already small living space gets even smaller, when insulating at the inside.
Ceiling and Loft
The insulation thickness at lofts should at least be 200 mm, and all parts of the construction with surface to the open air must be insulated. It will often be smart to insulate flat roofs at the outside. At the same time it is possible to establish a sloping roof.
Floor
Floors over crawl space or unheated cellars are often easiest to insulate from below, by putting up insulation plates between beams. The simplest way to insulate floors directly on the ground (terrain floor) in houses without cellar, is vertical insulation of the plinth and foundations. Terrain floors can also be insulated with 50 mm of mineral wool at top of an existing concrete floor.
Windows
The heat loss can be reduced by replacing the old windows with sealed units, or even better heat mirror windows. Heat mirror windows insulate nearly twice as good as ordinary sealed units with air-filling.
Electricity Conservation
In most of developed countries the total gross energy consumption has not changed in last 10-15 years, while the electricity consumption has increased. Efficiency of the individual electric device has improved during the same period, so the increased consumption is due to more electrical appliances than before. The situation in CEE is a little bit different to those in EU. CEE households consume far lees electricity than their counterparts in e.g. EU. Nevertheless expected increase of life standard will certainly change the situation and special considerations should be devoted to this sector.
Large electricity consumers in the household are lighting, laundry, cooling, and cooking. Higher consumption is introduced, because we get more and more electrical appliances. There are large technical possibilities for rational use of electricity. New efficient devices on the market consume considerable less electricity than older models. By utilizing the technical potential of savings, it is possible to save of electricity consumption . When replacing old appliances, the electricity consumption ought to be examined carefully, as the most energy consuming appliances consume up to 3 times as much electricity as the most efficient on the market see the following table (5).
best worst
kWh/year kWh/year
Refrigerators, 130-189 l. 219 310
Refrigerators, 190-259 l. 102 347
Refrigerators w/ freezer, 255 420
130-189 l.
Refrigerators w/ freezer, 310 438
190-259 l.
Refrigerator and freezer, 365 985
190-259 l.
Refrigerator and freezer, 474 766
260-349 l.
Chest freezers, 170-249 l. 182 515
Upright freezers, 170-249 l. 328 766
kWh/time kWh/time
washing machines, 40-48 l. 1.6 2.5
Dishwashers, 12-14 covers 1.4 2.0
It is important to work on regular labelling of electrical appliances, so the consumers have a chance to compare the different products when shopping. There are further savings to be achieved by correct use of the electrical appliances, as well as it is necessary to consider, if we need all these electrical devices at all. The energy service dry clothes can easily be obtained without using a tumbler, thus without consuming electricity.
Lighting
The most common source of light in homes is the incandescent lamp, and in some places the more efficient fluorescent tubes. But during the last years have been developed low energy light bulbs (Compact Fluorescent Lamps, CFL), which in principle work the same way as fluorescent tubes, but they fit in an ordinary holder. In contradiction to fluorescent tubes, electronic low energy light bulbs can stand being turned on and off again and again, without reducing the life span. CFL light bulb can save up to 80% of electricity in comparison to traditional incadescent one.
The commercial sector is harder to cover for the energy offices compared to private homes. It needs more technical knowledge, and expensive measuring instruments are in general required. It is also natural for a company to make use of a consulting engineering company or the power utility, if the company wants to do something on its energy consumption.
Company Character and Economy
The energy use is very dependent on the character of the company. Typically the demands are:
The companies can be using electricity, heat, and the fuels natural gas, gas oil, fuel oil, coal, and biomass.
THE BARRIER :
The low energy price as it is common in CEE countries gives the conservation measures a longer pay back time. And into the bargain the companies usually make severe demands on the pay back period: Over three to four years are seldom accepted.
Even if the rentability of a conservation measure is acceptable, there is a high risk that it will not be implemented. The main aim of a company is to produce goods or deliver services, and the resources of the company in terms of staff and capital are therefore reserved for these purposes. The energy consumption has low priority.
The arguments for energy savings targeting the company are:
Working reliability is often the best argument, because production stop as a rule are expensive.
It is seldom that the company knows how much energy is spent on each device and what is the total energy efficiency (inefficiency) of their facilities. This situation opens the room for energy audits which can give the company proposals for energy savings and their rentability.
Consumption and Conservation
USEFUL TIPS:
Space Heating and Hot Water
Energy consumption related to heating buildings and hot water, can be reduced by the same measures as for dwellings: Afterinsulation, better insulated windows, tightening, lower room temperature, water saving devices, and lower hot water temperature. The possibilities are described more deeply in the previous paragraph on energy conservation in households.
Light
The cheapest advice is, remember to turn off the light when it isn't needed. Especially at work many people forget to turn off the light. It may be in corridors and storerooms, where the staff seldom are, but where the light anyway is on all day. Or in offices, where the light was turned on in cloudy weather, but not turned off again, when the sun came back.
Even fluorescent tubes must be turned off. Provided one is leaving the room for more than a few minutes, fluorescent tubes must be turned off. The life span is only slightly reduced, and the extra electricity consumption related to keeping the light on, costs far more than changing the tube a little more often.
The second cheapest advice is to keep shades clean. It gives no direct energy conservation, but might cause that some of the lamps can be turned off, because the rest provides more light.
Next step is to change the lighting. The easiest way is to substitute incandescent lamps with fluorescent lamps, and old fluorescent tubes with new, thin, and efficient types. Halogenic lamps save a little compared with incandescent lamps, but not as much as fluorescent lamps. One has to realize that halogenic lamps run on low-voltage, and therefore are plugged through a transformer. Even though the lamp is turned off, there is loss from the transformer, which means that it consumes a small amount of electricity all the time. The loss makes the transformer feel warm. Therefore the switch must be turned off, and not only the lamp.
By reducing energy consumption for lightening, the heat from light is also reduced. If the offices are ventilated or cooled, the consumption for this also decreases.
Office Appliances
A cheap piece of advice like for the light: Turn off, when not in use. In most offices all computers, printers, photocopiers, telefax machines, etc., are turned on, from the first person arrives, till the last goes home. At larger workplaces some of the appliances are not even turned off before the night watcher makes his round. If it is a problem to remember turning off the appliances, timers that turn off the appliances outside office hours can be installed. When buying new devices the energy consumption ought to be considered.
Ventilators and Blowers
Ventilation is used for providing a satisfactory indoor climate, and remove unpleasant or toxic substances from a production.The simplest saving is, only to run the installation, when there is a need. If thermostats, or other automatic, are installed, it must be ensured that they work properly. There can be a need for supplementing the control with timers and motion detectors. Some ventilation plants can run at variable speeds, and it is therefore possible to choose the performance that fits the need. Moreover exist regulators with infinitely variable regulation of the performance. Filters on the plant also must be cleaned frequently.
Pumping
There exist plenty of inefficient pumps in the heating installation, and pumps moving liquids in the production. At first it must be secured that the pumps only are working, when there is a need. Second that the efficiency is adjusted to the demand. A valve reduces the volume flux, but does not save electricity. Some pumps have a built-in regulator with variable speeds, where the lowest performance gives lowest electricity consumption. Some pumps have electronic control for infinitely variable regulation. It is possible to mount the control on pumps without regulator. If a pump has to work at both low and high performance, it might be an advantage to rebuild, so there are more pumps being coupled in, according to demand. Furthermore it must be secured, the size of the pump is adjusted the plant. By replacing the pump and maybe the engine, if pump and engine are not integrated, the efficiency probably can be increased.
Refrigeration
There might be large savings to achieve in relation to refrigeration plants. This counts for plants in both shops and industry. It must be secured that the plant does not work, when there is no need for refrigeration. This especially counts for freezers, which are only in use during production. Cold stores for storing goods must of course run constantly. Various methods to regulate the performance of the refrigeration plant exist. Improved management can lower consumption. Some refrigeration plants utilize the condenser heat for space heating or hot water. This is a good solution, but only if the condenser temperature isn't raised to get hot air or water. Instead it is more profitable to install a heating element for the last heating. Replacement of motor, and perhaps transmission between motor and compressor, might raise the efficiency.
Compressed Air
Compressed air is used by industry to run tools and valves, etc., and to blow products clean. It must be ensured the plant is only running, when compressed air is needed. The plant must be adjusted at the needed pressure, and not higher. Cleaning of filters in the installation can lower the pressure loss.
The air drawn in must be as cold as possible, as the electricity consumption decreases, when the air density increases. Therefore it is preferable to draw in air from the open.
There might be many leakages in the piping. By tightening, the compressor performance is decreased, and with this the electricity consumption.
As regarding refrigerator compressors, there are more ways to control them. Changing the regulation might in some cases lower the consumption.
If the air compressor is only used for pneumatic tools, it might be an advantage to scrap the plant, and use electric tools instead.
If there is a heat demand at the factory, it is possible to regain the heat from the compressors.
Engines
Engines are used in industry for running machines, belt conveyers, etc.It must be ensured that the engines only are running when needed. All parts must be regularly cleaned and maintained.
The engine size must fit the demand of the appliance. Often the engine is oversized, causing too high electricity consumption. By alternating need of performance, electronic regulation results in the lowest consumption. It is also possible to have more engines of different size, or one engine which can work at two speeds. If the engine is low efficient it might be profitable to change it.
Process heat
Heat can be used for heating, evaporation, drying, melting, etc.The energy source is electricity or fuels like natural gas, oil, and solid fuel. Energy economic it is in general advantageous to utilize the fuels, as loss at the power plant is avoided. Though electrical heating might be easier to control than fuels.The process heating must be controlled, so there only is consumption when there is a need.
The demand must be decreased as much as possible, for example by insulation to less heat loss. As well as the temperature must be lowered as much as possible.
Concerning drying processes, the consumption can be decreased by removing as much moist as possible before the drying, for example using a hydro extractor.
It might be possible to regain heat from a heated product, and use the heat to preheat a new product.
If fuels are used for heating, the combustion must be with smallest possible loss. Air inlet must be adjusted to maximum efficiency. A poor insulated boiler can lower consumption if insulated.
Decentralized combined heat and power production - cogeneration - is a very flexible and efficient way of utilizing fuels. Cogeneration of biomass is environmentally friendly, and all kinds of biomass resources can be used.
Cogeneration why ?
It is a fundamental physical condition that not all latent energy of a fuel can be converted into tractive power, e.g. to run a car. The main part of the energy is necessarily transformed to waste heat which in the car example disappears by motor cooling and with the exhaust.
Cogeneration plants can be used in all situations where a given heat demand exists. This include all together an extremely large number of district heating plants, institutions, cooperative building societies, industry, etc.
For the cogeneration technologies described in this chapter the primary interest is due to, that a very large percentage of the fuel's energy content is utilized, typically 8595%. This must be compared to the relatively low energy efficiency of centralized thermal power plants; the annual mean efficiency is about 40-50% in developed countries but only around 30% in CEE countries.
Another important reason for the interest in decentralized cogeneration is the possibility to utilize renewable bio fuels: straw, wood, manure, etc. There are furthermore a few circumstances which are not that much noticed in the political debate.
Decentralisation of power production
First of all a large number of cogeneration plants increase the security of power supply. It is not usual that the large power units break down, but it happens. It is obvious that the consequences of missing a large unit are much more significant, than if it is one of the much smaller cogeneration plants.
Second there is a considerable energy loss from the power grid. In CEE region it is good 7-9% in average. But this figure covers very large variations through the day, and furthermore depends very much on which voltage level it is. Thus the energy loss from the lowvoltage grid is much larger than from the highvoltage grid. All in all this means that e.g. on a winter day at 5pm there is a large energy loss from the lowvoltage grid. Exactly because many of the cogeneration plants are coupled on the lowvoltage grid, they also reduce the grid loss which influence the overall energy efficiency.
FACT :
The rays of sun light each year provide the earth 20.000 times the energy we consume. Even the roof of a single-storeyed house in the not very sunny Northern Europe receives ten times as much energy, as the house needs for all year heating.
Though human cultures have used solar energy for millenniums, solar heating systems are a new technology, which has been utilized in Europe since the end of the seventies. Today solar heating plants are profitable in many situations in Europe. This is primarily true for plants heating domestic hot water and swimming pools, various solar drying plants, and simple passive solar heating design.
The energy received from the sun, balance with the heat emission from the earth to the sky. On its way, the energy is borrowed by the nature to keep the circles running. With a solar plant we can do the same.To design solar heating systems, a general view of energy content, variation, and characteristic of the solar irradiation is needed. In Northern of Europe the energy content is more than 10 times bigger during summer months than during winter months (in Southern Europe 5 times), and it varies appr. 20% between sunny and not very sunny years.
A great deal of the solar energy is received as diffuse radiation, which means energy irradiation from the sky, and not directly from the sun. The diffuse radiation can be captured by flat plate solar collectors; but it can not be concentrated by mirrors. This is the reason, why concentrating solar collectors have a relative small output here, compared to other parts of the world, where the amount of direct solar irradiation is larger.
TIPS:
Theoretically the optimum location of a solar collector is a south facing surface, with the same tilt angle as the latitude of the place. In practice there will always be shadows at the horizon, which means that the optimum is a slightly more level location. If the wish is to optimize on respectively summer and winter output, the tilt angle of the solar collector must be more level respectively more sheer. A small deviation from the optimum orientation and inclination of a solar collector is not of practical importance. A solar collector that traces the sun, will receive about 20% more solar radiation than a south facing optimum placed collector. This additional output do not compensate the costs related to a construction, which has to trace the sun. Usually it will be cheaper to install a 20% larger solar collector.
Domestic Hot Water Systems
The most widely distributed utilization of direct solar heating is for hot water production. An installation consists of one or more collectors in which a fluid is heated by the sun, plus a hot-water tank where the water is heated by the hot liquid.
Solar water heaters are very popular in places like Greece and Israel. They are now gaining a footing in other parts of Europe as well where both the State and popular energy offices have put a lot of work into solar heating campaigns aimed at single-family houses.In most parts of Europe a solar heating plant can provide 50-70% (in Southern Europe up to 90%) of the hot water demand. It is not possible to obtain more, unless there is a seasonal storage.
The simplest installations are thermosyphon systems, with the storage tank placed above the solar collector. The temperature difference between the solar collector and the storage forces the circulation of the collector fluid, when the sun is shining, and heats the solar collector. This type of installations is popular in sub-tropical and tropical areas, especially units with integrated solar collector and storage tank. It is more difficult to utilize the thermosyphon solar collectors in Europe, because of frost problems at the storage tank.
Solar Heating for Combined Space Heating and Hot-water
An active solar heating plant can provide hot water, and additional heating via the central heating system at the same time. To get a reasonable output, the central heating temperature must be as low as possible (preferably below 50°C), and there must be a storage for the space heating. A smart solution is to combine the solar heating installation with under-floor heating, where the floor function as heat storage.
Solar heating installations for space heating usually give less profit than hot-water installations, both according economy and energy, as heating is seldom needed during summer. But if heat is needed during summer, then space heating installations is a good idea.
In Northern Europe a solar heating plant can cover up to 30% of standard annual heat demand. In some places like the Alps, the total consumption can nearly be covered, as heat is demanded all year round, and simultaneously winters are sunny.
Solar Heated Swimming Pools
If it is wanted to heat up a swimming pool a few degrees above outdoor temperature, a simple solar heating plant can be used, where the pool water is pumped through plastic collectors without cover. Due to low price and high output, this kind of solar collectors has become very popular in several places in Europe, first of all for outdoor swimming pools.
Solar Heating for District Heating Plants
Large solar heating plants for district heating are now in use, e.g. in Denmark and Sweden. For this purpose are constructed large solar modules, which are practical to install directly at the ground in larger fields. Without a storage a solar heating installation can cover appr. 5% of the annual heat demand, as the plant never must produce more than the minimum heat consumption, including loss in the district heating system (by 20% transmission loss). If there is a day-to-night storage, then the solar heating installation can cover 10-12% of the heat demand including transmission loss, and with a seasonal storage up to 100%.
Another possibility is to combine district heating with individual solar water heaters. Then the district heating system can be closed during summer, when the sun provides hot water, and there is no need for space heating.
Seasonal Storage
To cover the total heat consumption by solar energy in a house in Europe, a storage that stores heat from summer and autumn is needed. Since water is a very efficient storage agent, a lot of experiments with large water storages have been carried out. Actually a house can be heated all year round by a solar collector combined with a super-insulated tank with the same volume as the house. But in practice this solution is far too expensive.
The most promising seasonal storages are large storages in connection with district heating, because large water storages are cheaper and with less loss per m3 than smaller storages. Some pilot and demonstration plants with seasonal storage have been build in Sweden. They have experience on seasonal storages in concrete tanks, in pools with insulated cap, in blasted rock caves, and in bore holes where the heat capacity of the soil contributes to the storage (6).
Drying of Crops and Houses
A solar collector that heats air, can be used as a cheap heat source for drying corn and other crops. The solar air-collector may consist of a black mat covered by a plastic plate. The air is drawn through the mat, where it is heated, and thereafter blown through the crops. A damp house or room can also be dried out by blowing hot air from a solar air-collector into it. By using a photovoltaic driven blower, it can be secured that only when the sun shines, air is blown in. Such installations are commonly used in summer cottages in Denmark and Sweden, where they keep the houses dry most of the year.
High Temperature Solar Collectors
If temperatures over 100°C are needed, e.g. for industry, or steam to generate electricity, there exist various possibilities with high temperature solar collectors. The most successful type is a concentrating solar collector made by Luz; a parabolic trough reflects the solar radiation to a black tube in the centre of the trough. This type is used at some solar power plants in California, but it would not be very efficient in Europe, while it can not make use of the diffuse solar radiation. In Europe are manufactured flat-plate solar collectors with evacuated tubes, which can produce heat at temperatures from 100 to 200°C. Furthermore flat-plate solar collectors covered by air glass (an efficient, transparent insulation material), for the temperature range 100-200°C are under development.
Finally exist some pilot plants, e.g. in France and USA, consisting of a large number of mirrors that reflect the solar radiation onto a central absorber, where steam is produced and used for power production.
Hand Rules
According solar water heaters (heating from 8 to 45°C) with south facing, oblique solar collectors, which have selective absorbers, the following rules can be used:
* 1-1.5 m2 solar collector area is needed per 50 litres daily consumption of hot water
* the storage tank shall be 40-70 litres per m2 solar collector
* the heat exchanger in the storage tank shall be able to transfer 40-60 W/°C per m2 solar collector at 50°C.
If these guidelines are followed, a solar water heater is able to produce 350-550 kWh/m2. With an installation like this, the additional heating can be turned off during 3-5 summer months, and idle loss from a furnace is cut.
Building Design with Passive Solar Heating
The most simple form of passive solar heating is orientation of the windows, so all larger windows face south. A house with south facing windows needs 15-25% less heat supply than a similar house with east and west facing windows. The saving is largest, if the inner part of the house is build of heavy materials that absorbs heat, and it has low energy windows.
Large south facing windows ought to be combined with shadowing overhangs, that prevents overheating during summer. Passive solar heating design is popular in some places in USA, e.g. in New Mexico, where barely one house without passive solar heating considerations is build. More and more European architects use passive solar heating design for new buildings as well as renovation.
Glass Annexes
An unheated glass annex at a south front e.g. a greenhouse, a glazed-in balcony or patio, contributes to the heating. The heat saving is due to three conditions:
Roughly estimated, the glass annex can save half of the heat loss from the facade behind it. The saving totally depends on, how the house and the glass annex is used. If the doors and windows between the house and glass annex not are closed, or the glass house is heated, it may result in a higher heat consumption than without the glass annex.
The heat conservation due to a glass annex do not justify its construction, neither economic nor energy-economic (the energy pay back period is 10-14 years). The reason why glass annexes still are popular in some parts of Europe, are the possibilities they provide, such as extra living space when the sun is shining, or a greenhouse, and they reduce the need for maintenance of the facade.
HAND RULE
Passive use of sunlight contributes around 15% of space heating needs in typical building.
The first photovoltaic cell of silicon, which had an efficiency of appr. 6%, was produced in 1954 at the Bell Laboratories in USA and in 1958 the first photovoltaics were sent out in space by the satellite Vanguard 1.
The tremendous price increase on energy in the beginning of the 1970'es led to, that big amounts were invested in improving the photovoltaic technology. The development has gone through several generations, each with improved efficiency, increased life span, and lower production price. One of the significant conquests is the mass production of cheap amorphous (poly crystalline) silicon cells.
Today exists a large choice of products, that utilize photovoltaic processes for energy supply. Pocket calculators, wrist watches, and signal devices for navigation and aviation, are just a few examples from our daily life.Photovoltaic cells are used for producing electricity, where the previous mentioned solar technologies produce heat. Photovoltaics can be used for many purposes. But in grid-connected areas they are still not economical competitive.
Houses lying in remote areas can profitably use photovoltaics for lighting, cooling, communication, and TV. For pleasure boats (sailing boats) it is a big advantage to use photovoltaics for recharging batteries, and supply for instruments, navigation light, radio, light, and maybe refrigerator. Photovoltaic cells are also used for operation of signalling lights for navigation and aviation. E.g. the light buoys that mark the submerged rocks. In the developing countries there are other purposes. The photovoltaics are used for operation of refrigerators for vaccine and medicine. Photovoltaic installations are often utilized for pumping drinking water and irrigation. The Photovoltaic cells are also used for operation of transportable dental clinics, smaller machines, plus for light, radio, and TV. Many signal and communication installations are also equipped with photovoltaic cells.
PV CELLS
Today exist various usable types of photovoltaic cells. Mono crystalline cells, poly crystalline, and amorphous cells. Silicon is made from quarts (SiO2), which exists in large quantity in nature. The used silicon must be very pure, and for the production is used a lot of energy for heating. There are also used strong chlorine-containing compounds and trichloride. The pure silicon is doped (polluted), e.g. by boron, and thereafter various substances are steamed on. Parts of the production processes are secret, as a costly development is taking place. The development is heading toward still thinner substrate cells, double function cells, and tandem cells. In the future we will also see granular photovoltaic cells with lower efficiency, but at considerable lower price than today's photovoltaic cells.
Solar Radiation and Efficiency of PV Cells
The efficiency is calculated as the percentage difference between the irradiated effect (Watt) per area unit, and the effect supplied from the photovoltaic cell. There is a distinction between theoretical efficiency, laboratory efficiency, and practical efficiency. It is important to know the difference between these terms, and it is of course only the practical efficiency which is of interest to users of photovoltaics. Silicon cells have a theoretical efficiency of appr. 28% and a practical efficiency of 14 to 16% (1992). By using other semi-conductive materials and other production methods, the efficiency can be increased (7).
TIPS and Applications
When designing a photovoltaic installation a lot of things must be taken into consideration, if an optimum solution is wanted. At first it must be clarified, how much energy is demanded from the photovoltaic installation. After that the total daily consumption in Ampere hours (Ah) must be estimated. From the total daily and weekly consumption the total energy storage capacity can be calculated. It must be considered how many days without sun, the installation shall be capable of functioning. At the end it can be calculated, how many photovoltaic modules are required to produce sufficient energy. The photovoltaic application can also be combined with other energy sources. A combination of small wind generators and photovoltaics is an obvious possibility. The energy can be stored in ordinary lead batteries, in nickel/cadmium batteries, in sodium/sulphur batteries, or by cracking water to hydrogen.
Life Span, Pollution
Photovoltaic cells produced today have a durability of at least 30 years and can not be produced or scrapped without pollution, the used batteries can neither. These circumstances must be taken into consideration, when calling photovoltaic cells a supplier of non-polluting energy. There has to be invented production processes, which harm the environment as little as possible.
Future and Perspectives
The mono crystalline silicon cells are today the backbone of professional applications like communication and energy supply in remote areas. The advantages are high efficiency (relative) and stable operation for many years. The disadvantage is a high price, as this type isn't suitable for mass production.
Thin-film cells and granular cells are the future. The advantage is lower price due to a continuous production. The disadvantages are, that these types are not ready yet, they are not stable yet, and their life span are still short.
HAND RULE
In a typical photovoltaic system based on crystalline Silicon with 12% efficiency each kWp of installed power capacity can produce 1150 kWh of electricity per year for grid connected systems and 300 kWh/yr for stand alone systems in Central Europe.
At the beginning of this century windmills were commonly used in Europe. These mainly supplied tractive power directly to the agricultural machines . After oil price shocks technology to convert wind energy to electricity gained on importance and commercial utilization in some developed countries (USA, Denmark) was very successful.
EXAMPLE TO FOLLOW - DANISH EXPERIENCE
At the beginning of 1992 there were erected appr. 3230 wind turbines in Denmark alone, and these turbines generate appr. 3% of total electricity consumption in this country (in some regions like Jutland 40%).
The energy crisis in 1974 initiated design of smaller household wind turbines. The development began at grassroots level, and with many inventors and pioneers involved. The motives were many, and to great extend characterized by idealism and the debate on introducing nuclear power in Denmark. The first commercial wind turbine was sold in 1976. From 1976 to 1985 it was mainly the private sector, that established wind turbines in Denmark. The turbines were either single ownership or joint ownership installations. Joint ownership wind turbines were established by wind turbine cooperatives. Some turbines were not connected to the grid at the beginning, but today all commercial wind turbines are grid-connected. From the early 80es the size of the turbines grew from 55 kW, until today where the mean size of established wind turbines is 200 kW. Today Danish wind turbine manufacturers produce commercial turbines up to 500 kW (8).
From 1985-92 both private persons and the power utilities established wind turbines. Against a background of a political deal between the government and the social democrats in 1985, the power utilities were enjoined to establish wind turbines. In 1991 the power utilities were asked to establish another 100 MW wind power. Today appr. 75% of all Danish wind turbines are privately owned, and only 25% are owned by the power utilities.
A fundamental feature of the Danish development has thus been the involvement of the private sector. An essential factor in the first stage was 30% state subsidy for establishment of private owned wind turbines. This support was given to the buyer of the wind turbine, thus supporting a private market for wind turbines. Compared to other countries this kind of subsidy has shown to be more efficient in initiating a technological and mercantile development of wind power. The wind turbine manufacturers thus have been able to develop bigger and more efficient machines all the time, while sale to a quite stable home-market has been secured.
An important basis for the establishment of private wind turbines has been agreements on payment rates for electricity produced by grid-connected wind turbines. A 10 years agreement was contracted by private turbine owners and the power utilities. But this agreement was dropped by the power utilities in 1992, and has subsequently been replaced by legislation in the field. Together with the state subsidy for establishment of wind turbines, private turbine owners got the electricity tax repaid. Fixed payment rates and tax repayment have been the financial basis, and secured reasonable private economy when establishing wind turbines.
In order to calculate the production from a wind turbine on a certain location, it is necessary to know the landscape around the wind turbine. The less obstacles in the landscape, the more windy. Trees, farms, forests, and cities, slow down the wind. The wind energy has its maximum at sea, where no obstacles decelerate the wind.
Environment
The electricity produced by wind turbines should alternatively have been produced at a thermal power plant using fossil fuels, thus polluting with carbon monoxide, sulphur, nitrogen oxides, dust, cinders, etc. Of course there are spent energy and resources to produce the wind turbines, but from then the wind turbine produces energy without polluting. The energy pay back period is less than half a year for a good located wind turbine. Thus wind power must be characterized as one of the cleanest power production methods today.
However establishment of wind turbines are not totally without environmental impact The main environmental problem concerning wind turbines is, that they are noisy. In Denmark e.g. environmental legislation regulates, how much noise a wind turbine is allowed to emit, and which noise level the neighbours must be exposed to. A single standing wind turbine can be placed appr. 150 m from the nearest housing, and still keep a maximum noise level of 45 dB(A). For larger estates the noise limit is 40 dB(A), which leads to a minimum distance of 250 m.
Small-scale and Stand-alone Windmills
It was the small household turbines that started the development in the 70es. These were later developed to the larger grid-connected wind turbines, and the improvement of the small and not-grid-connected wind turbines more or less stopped. In the last years has anyway appeared a new interest in utilizing and developing smaller turbines for alternative purposes.
The various existing types can be parted in:
The two first categories (small battery charging turbines, and small wind turbines rating 1-20 kW) are named household turbines or just small turbines.The technology in small turbines can be quite simple, demanding little maintenance.
Biomass is a local energy source which relatively easy can replace large amounts of fossil fuels for heat and power production. Bio-energy is CO2 neutral and therefore a significant factor in the fight against the greenhouse effect.
Biomass is the renewable energy source that can be developed most rapidly . Today it accounts for more than 14% of energy supply in Sweden and 10% in Austria - the Austrian figure was achieved in less than a decade.
The advantage of biomass is that it can largely be produced and used without major technological investment. This is of particular importance to less developed countries.
Advantages of biomass energy utilisation
BIOFUELS
Wood has been used as heat source, as long as anybody remember. And as subsistence on Earth implies a certain amount of vegetation, this possibility will always exist.
During the last years, other crops have become important for energy purposes - e.g. straw, elephant grass, and rape. There are many possible applications, but today they are limited, one of the reasons being that these fuels requires more working up than available fossil fuels.
The use of straw for energy purposes is strongly increasing, partly for environmental reasons (in some countries it is prohibited to burn straw at the fields), and partly because it often is profitable even with a low efficiency.
Today both wood and straw are waste products from corn production and forestry, windbreak belts, etc., - while other biomass products as rapeseed oil, elephant grass, and energy crops, are grown directly for energy purposes and therefore require larger supply of energy before the fuel is ready for use. Growing of biofuels on large scale may also have adverse consequences, as exhausting of soil and other environmental drawbacks, if it is monoculture production using pesticides and fertilizers.
Combustion of Biomass
The amount of CO2 being absorbed during plant growth and emitted during combustion as the primary way of utilising biomass energy is the same. Therefore, biomass is a CO2 neutral fuel, wieved over the time span it takes new plants to reach a size that makes them useable as fuel. For straw it is normally less than one year and for ordinary trees about 15 years.The CO2 relation is the same for oil, coal, and gas, but the time span needed to restore the CO2 balance is several millions years.
By a total combustion of biomass nitrogen oxides (NOx) form, besides CO2, water, and heat. NOx do not origin from the biomass, but from the nitrogen in the air which is consumed by the combustion together with oxygen. This consequently happens in all combustion processes where atmospheric air is added to have oxygen. NOx combines with the moisture in the air and form nitric acid. The amount of NOx depends on combustion temperature and the amount of surplus air.
Energy Content
The energy content in 1 kg of dry wood is 4.5 kWh. This corresponds to, that 2 kg wood are needed to replace 1 litre of fuel oil, if both are burned with the same efficiency. By increasing moisture content the energy content decreases, until the moisture content is so high that a total combustion is impossible, followed by a drastic decrease of combustion efficiency.
Environmental Aspects
Wood e.g. is completely decomposed in a proper combustion. It must be said to be our most environmentally compatible fuel (except hydrogen), as the only pollutants are NOx, which appear from every combustion where atmospheric air is used. If the combustion, on the other hand, is incomplete then some harmful and malodorous substances appear, which can be of great inconvenience in the local environment. However, they are not comparable to the substances that occur from combustion of oil and coal and may do irreparable harm to the global environment.The smoke shows, if the combustion is complete. The more black it is, the worse is the combustion. White smoke is not due to bad combustion, it is the moisture vaporised from the wood.
Combustion Technologies
Both wood and straw can be utilised in district heating systems with automatic stoking.Straw can be used as bales or chipped, whereas wood almost solely can be used as chips. The boiler efficiency will often be very high, but as the loss in the distribution system seldom is below 20% district heating systems are not able to compete with efficient individual plants.In district heating systems the need for storage can be diminished by using several smaller boilers, so the performance can be varied by taking one or more boilers out of operation.
POTENTIALS IN CEE
Huge amounts of unused (waste) biomass is still waiting for its exploitation in CEE. On local level this fuel could substitute fossil fuels and improve local environment. Forest and agricultural biomass energy potentials for some CEE countries according to NUTEK study: Forecast for Biofuel Trade in Europe are in the next table (9).
FOREST FUEL AGRICULTURAL FUEL
POTENTIAL POTENTIAL
PJ/year PJ/year
ALBANIA 4 2
BELORUSSIA 89 -
BULGARIA 84 34
CZECH 114 -
ESTONIA 72 -
HUNGARY 62 59
LATVIA 75 -
LITHUANIA 86 -
POLAND 244 104
ROMANIA 355 73
RUSSIA (EURO PART) 1483 207
SLOVAKIA 42 5
UKRAINE 75 -
rem. YUGOSLAVIA 58 42
POWER PRODUCTION
Wood and straw may be used in large thermal power plants. To avoid unnecessary transport demand, it will often be wise to look at the relation between the local straw/wood production and the energy demand at the same place.
An obvious possibility of generating power in connection with small stoves/boilers is the Stirling Engine which is characterised by being nearly unaffected by the purity of the fuel and very noise faint.
Gasification
With the increasing interest in utilising biomass for energy supply - and preferably for combined heat and power production - gasification calls for renewed interest. The gasification process is often called thermal gasification, because the biomass is heated in a chamber with controlled air supply.
It has been an important part of energy supply earlier; namely at coal gasifications plants wherefrom the gas was distributed through gas pipes and used in gas cookers, and the residue product, coke, was used for heating in solid fuel stoves. During World War II wood by means of a gasifier was used as petrol for cars.Like this, gasification is not a new phenomenon, but the technology was forgotten for many years because of cheaper and more handy ways of getting energy.The renewed interest in gasification of biomass, first of all straw and wood/chips, is due to the wish to utilise the rest products from agriculture and forestry, and encourage a more environmental conscious energy use. Here is mainly thought of the CO2 impact in the atmosphere.
A few companies in Europe and North America have developed gasifiers , but it is impossible to buy fully automatic and reliable gasifiers designed for cogeneration yet. Another characteristic of the recent plants is that none of them are capable of utilising straw and no technology to utilise the waste heat is developed. Up till now the technology development has mainly been directed towards third world applications, where abundant labour is available, and heat production is not that interesting.
HAND RULE
Each tonne of dry wood (etc. waste) with 16,2 MJ/kg heat value processed by gasification and used in gas turbine (GSTIG) can produce 1450 kWh of electricity.
BIOGAS
Biogas technology was introduced in the last century; first of all as a sanitary measure, as well as for reduction of volume and smell of the growing cities increasing amount of garbage. A real utilisation of biogas was only introduced in this century.
Today biogas plants gain prevalence all over the world as a method for energy production and recycling of nutrients for cultivation of plants. The sources are farmyard manure, plants, remains of plants, and organic waste from industry and households.
Biological process and its utilisation
In the biogas process high-molecular organic material is cracked to low-molecular, inorganic substances and gas by means of anaerobic (oxygen free) bacteria:
Biomass + Bacteria Gasses + Nutrients
The decomposition more or less corresponds to the processes which takes place in the nature, but with the difference that the natural processes mainly take place under presence of oxygen (are aerobic). Therefore the intermediate products of the processes are different, as well as the chemical composition of the end products.
In traditional agriculture the alternative of using farmyard manure for biogas production is to put it on the fields where it decomposes in an aerobic process. This process go off slowly and nutrients (e.g. nitrogen) risk being washed out before the plants manage to absorb them. Likewise, the energy potential of the biomass is not being utilised.
In a biogas plant the biomass is converted into for instance methane which is collected and utilised for energy production. The degassed biomass (bio sludge, or liquid and solid manure) with a great part of the nutrients on mineral form can easily be utilised in traditional agriculture, as it is very similar to fertiliser. At the same time the degassed manure is provided some positive elements compared to untreated farmyard manure. As less nutrients are lost than in traditional treatment of manure, the consumption of fertiliser and matching production and distribution is decreased.
In a biogas plant the biomass is heated up to the process temperature in an air tight reactor and a sufficient process period is secured. The usual process temperatures are either in the mesophile area (30-40°C) or thermophile area (50-60°C) and with 10-20 days stay in the reactor. The process are quicker at high temperature that is why the staying period and the reactor volume can be decreased. On the other hand, the demands for process control and heat recovery are larger with high process temperature.
Today the thermophile process is considered easy to control, and construction projects that are big enough to include investment in heat recovery, are mostly based on the thermophile process in which way also the highest hygienic standard is achieved. Especially when handling human waste, as kitchen waste and waste water, that later will be used in agriculture, a high hygienic standard is demanded by veterinary authorities. This can be achieved by securing that the material is 55 °C for at least 4 hours or 70°C for 1 hour.
The biogas formed in the process is a mixed gas consisting methane 60-70%), carbon dioxide(30-40%), hydrogen sulphide, as well as traces of H2 (hydrogen) and N2 (nitrogen). The combustible part is methane which has a heating value of 10 kWh per m3 CH4. This means that biogas has a heating value of 6-7 kWh per m3 biogas.
Biogas Potential
The biogas production in agriculture is based on farmyard manure which nowadays often is supplemented with other biomass to optimise the biogas production and profit. The supplement increases the content of nutrients and in some cases generates profit from receiving organic waste products which otherwise would cost the producers more to get rid of in another way, e.g. at deposits.
The biogas potential in farmyard manure with a dry matter content of 5 % are of the order of 0.2-0.3 m3 CH4/kg of volatile organic dry matter or 100-150 kWh per tones liquid manure. The potential depends on how the animals are fed and how they digest the food, in addition to the dry matter content. The variation is therefore very big.
In general the following normative figures for biogas potential in manure from different animals can be used:
1 cow (500 kg) 7 kWh/day 1 sow (150 kg) 2 kWh/day 10 porkers (60 kg each) 9 kWh/day 200 poultry 10 kWh/day
Joint biogas plant
During the last years special efforts have been made to build and test centralised joint biogas plants where the farmyard manure from several farms are transported by slurry tankers to centralised treatment together with other kinds of organic material. The degassed manure is brought back to the manure tanks at the farms or to new-built storage tanks at places where the manure will be utilised, again by slurry tanker.
World-wide 2100 TWh of hydro energy is produced every year. It provided 18% of all electricity produced and represents by far the largest amount of energy produced from renewable sources (the share of electricity produced from other renewable energy sources was 1,1%).Hydro power is a mature technology with many positive features.
Large hydroelectricity (power of more than 10 MW) represents an important potential resource in the world, but its intensive exploitation entails very serious consequences for the environment . This is the case particularly when dams are located in plain regions (Danube). Conversely, small hydro power plants (power of less than 10 MW) mostly do not represent a major challenge for the environment. They might nevertheless contribute to diversification of production sources and the use of derived renewable energy sources. The impact of small hydro power plants on the environment , though not negligible , can be controlled more easily . In CEE (except of former USSR) countries the highest unused potential for building small hydro power plants can be expected in Bulgaria, Romania, Poland and Slovakia.
SMALL HYDRO POWER PLANTS
Small hydro power plants are in large majority connected to the electricity grids. Most of them are of the 'run-of-river' type, meaning simply that they do not have any sizeable reservoir and produce electricity when the water provided by the river flow is available but generation ceases when the river dries-up and the flow falls bellow a predetermined amount.
Small hydro schemes have different configurations according to the head. High head schemes are typical of mountain areas, and due to the fact that for the same power they need a lower flow, they are usually cheaper. Low heads schemes are typical of the valleys and although they require turbines do not need feeder canal.
In the 1950s and 1960s, the nuclear-energy focused policies of energy suppliers were concentrated on eliminating small and medium-sized private producers in Germany and others European countries as well. The monopoly of these larger concerns meant that almost all hydropowered energy stations were forced to shut down. However recent trends in many European countries are stipulating that energy suppliers had to allow private suppliers of electricity to enter the public network again. Renovation of old plants thus seems to be very attractive from economical point of view.
Decision -making process whether to build hydro power plant, where and how should be seriously evaluated at the very begging .Among most important features to be considered are :
Of the numerous factors which affect the capital cost, site selection and basic layout are among the first to be considered. Adequate head and flow are necessary requirements for hydro generation
Evaluation of the water resource
In run-of-river schemes, the installed capacity and the annual energy production results from the rate of flow and the available head. The result of the hydrologic evaluation should strive to predict what the flows will be during the life of the project. The accuracy of this prediction depends on the availability of flow records and the time and financial resources available.
HAND RULE
In a typical small hydro power plant every litre per second (10-3 m3) of water falling down from 1 meter height can produce 20 - 30 kWh of electricity per year.
Height of 10 meters for example means that 300 kWh per year can be produced. 300 kWh/year can be produced also when height is 1 meter and the flow is 10 litres per sec.
POTENTIALS IN CEE
Energy potentials of unused hydro power in some CEE countries according to the Equipe Cousteau study The Danube for whom and for what? is following (10):
ANNUAL PRODUCTION
TWh
BULGARIA 2.5
CZECH REP. 1.66
HUNGARY 0,032
ROMANIA 4
SLOVAKIA 1,2
Geothermal energy as the natural heat of the Earth can be transformed to electricity or heat and thus provide us with huge energy supply.The Earth is continuously releasing energy everywhere. The temperature in the earth's crust increases with depth. Depth that are accessible by drilling with modern technology reach just over 10 000 meters.
HAND RULE
The average geothermal gradient is about 2,5 - 3C/100 m.
Geothermal sources can be found in areas with normal or slightly above normal geothermal gradient, provided that the hydrogeological conditions are favourable.
Geothermal energy is a proven source that uses mainly conventional technology. Commercial production on the scale of hundreds of MW has existed for more than 30 years both for electricity generation and for direct heat utilisation. Nevertheless environmental impacts of geothermal (mineral-rich) waters are frequently not negligible .
ELECTRICITY GENERATION
Twenty-two countries now generate electricity of geothermal origin, and by 1994 the total installed capacity world-wide reached 6333 MW. Conversion efficiencies for thermal energy are never more than 20% and are close to 5% on the smaller power plants. While this may appear very poor at first sight, it should be recognised that the geothermal resource is so large that minimising specific costs for the overall geothermal facility is the appropriate primary target rather than maximising the efficiency of the power plant alone.
DIRECT USE
The status of direct uses of geothermal energy (heat) is less well known than electricity generation. Geothermal water is used for district heating systems and greenhouses. In many European countries , hot water has traditionally been used to supply energy for drying , heating, agriculture, fish farming, etc. and for health and leisure purposes such as bath. However it is only during the last few decades that subsurface hot water has been used on a large scale for district heating system and electricity generation. The exploitation of a given geothermal resource and its utilisation technology are site-specific but the state of advancement in this field is mature.
GEOTHERMAL HEAT PUMPS
A relatively recent geothermal application has been the use of the ground as a hot or cold source for the input side of heat pumps. This is probably the most rapidly developing part of the entire geothermal industry in terms of annual growth. A world-wide review of these systems suggests that somewhere between 250 000 and 380 000 of these systems are now in operation. The current installation rate in the USA alone is about 40 000 per year.The primary drive for these systems is currently provided by the electric utilities for demand side management, peak reduction, load levelling and increased competitiveness against other fuels.
DEVELOPMENT IN CEE
UNITS AND CONVERSION FACTORS
1 Joule (J) = 278 . 10-6 Wh
1 kWh = 3,6 MJ 1 GJ = 277,8 kWh
1 kWh = 0,1 lt. of oil
BIOFUEL HEAT VALUE MJ/Kg STRAW 14,3 - 15 WOOD 13 - 16,0 BIOGAS 22,0 MJ/m3
FOSSIL FUELS
BROWN COAL 20 HARD COAL 29 - 32 HEATING OIL 42,0 NATURAL GAS 32 - 39 MJ/m3
k = kilo = 103
M= Mega= 106
G= Giga = 109
T = Tera = 1012
P = Peta = 1015
Other useful reading
CEE countries still have the unique opportunity to transform their energy consumption path towards an environmentally sustainable ones. Deficiencies of education and the unfamiliarity with democracy as a daily practice all hinder society from making decissions in the awareness of its own best interests. Information is indispensable for such awareness and the role of NGOs capable of representing these interests is crucial. Two NGO networks (INforSE and Greenway Energy Working Group) are actively involved in energy issues since 1991 and are trying hard to address the key issues (see Ways to Act). Groups which are not organized in this networks yet are welcome to joint them.
Ways to act
On national level NGOs should force governments to :
On international level NGOs should force the governments of OECD countries, the int. financial institutions (EBRD, World Bank, IMF) and the European Union (e.g. PHARE programme) to give priority to projects which focus on improving energy energy efficiency and renewable energy sources .
INforSE (Int. Network for Sustainable Energy), Skovvangsvej 191, DK-8200 Aarhus N, Denmark , NGO network
Greenway Enery Working Group, Frankel Leo u. 102-104 IV/40, H-1023 Budapest, Hungary, NGO network
IIEC- Europe (Int. Institute for Energy Conservation), 1-2 Purley Place, London N1 1QA, U.K.
WISE Int (World Info Services on on Energy). , POB 18185 , 1001 ZB Amsterdam, The Netherlands
ISES- Int. Solar Energy Society, Weisenthalstr. 50, 79115 Freiburg, BRD
IEA/OECD - Int. Energy Agency, 2 rue Andre Pascal, 75775 Paris, France