Question 1:- What are the natural energy sources suitable to sir Lanka and

describe them in detail with example Renewable energy sourcesWith the environmental conditions becoming worse day by day, people are trying their bit to save the environment by

using natural energy resources. The different types of natural energy resources are as follows:

Wind power – as the wind blows, the turbine blades start rotating. By using an electrical

generator, the rotation gets converted into electrical current. This electrical current is used on a small scale to provide

electricity to small homes, and is also harnessed by large wind farm, which gets used by national electrical grids.

 

Solar energy – the sun rays are trapped into solar cells, wherein, it gets transformed into

electricity and this is how solar energy is created. It is commonly used for taking salt out of water, and also used for

cooking, heating, and of course to produce electricity.

 

Geothermal energy – this natural energy is produced by the earth. Hot rocks present under the

ground heats up water, so that steam is produced. Holes are dug in such areas, and the steam shoots up, driving the

turbines. Electrical generators are then powered by these turbines.

 

Hydroelectric power – dammed water is used to generate this power, which then drives water

turbine and generator. One of the versions of this is tidal power. The power produce by water tides generates

pressure, which turns a water wheel or a turbine. The electrical generator gets energy from this power.

 

Biofuels – these are fuels that are made from plants or animals. It can include methane from wood, wood chippings,

and animal wastes. Biofuels are used to heat homes, to power machines, and for cooking.

 

Natural gas – it is a fossil fuel but does not generate carbon dioxide, which happens to be the chief greenhouse gas.

Thus natural gas is a better option. It can be created by various organisms, and is also found in areas which have

fossil fuels.

Nuclear energy – this is created though atoms. Either by merging or splitting atoms, energy is created. Though it

produces a large amount of power, it has certain hazards.

These are amongst the best natural energy resources, which helps to reduce electricity bills, and at the same time,

protects the environment.

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What is Renewable Energy?

Renewable energy is energy generated from natural resources—such as sunlight, wind, rain, tides and geothermal heat—which are renewable (naturally replenished). Renewable energy technologies range from solar power, wind power, hydroelectricity/micro hydro, biomass and biofuels for transportation.

Renewable energy is energy that is generated from natural processes that are

continuously replenished.  This includes sunlight, geothermal heat, wind, tides, water,

and various forms of biomass.  This energy cannot be exhausted and is constantly

renewed.

Alternative energy is a term used for an energy source that is an alternative to using

fossil fuels. Generally, it indicates energies that are non-traditional and have low

environmental impact. The term alternative is used to contrast with fossil fuels

according to some sources. By most definitions alternative energy doesn't harm the

environment, a distinction which separates it from renewable energy which may or may

not have significant environmental impact.

What is Biomass?

Biomass, is a renewable organic matter, and can include biological material derived

from living, or recently living organisms, such as wood, waste, and alcohol fuels.

Wood energy is derived both from harvested wood as a fuel and from wood waste

products.  Waste energy can be generated from municipal waste, manufacturing waste,

and landfill gas. Biomass alcohol fuel, or ethanol, is derived almost exclusively from

corn.

What is Biodiesel?

Biodiesel is fuel made from plant oils that can be used in diesel engines.  They are

typically made of renewable organic raw materials such as soybean or rapeseed oils,

animal fats, waste vegetable oils or microalgae oils.

INTRODUCTION TO RENEWABLE ENERGY

RENEWABLE ENERGY RESOURCES IN SRI LANKA

Due to the geo-climatic conditions, Sri Lanka is blessed with several forms of

energy resources. Sri Lanka is an island located in the tropics and surrounded

by the Indian Ocean.  The island receives rain from two monsoonal wind

regimes, viz., the Southwest and Northeast monsoons.  The island itself is

characterised by a central highland, lowland mountain ranges, flat terrains and

plateaus, which affect cloud formation.  The annual mean rainfall ranges from

750 to 5000mm, which in turn sources a perennial river system.  The high

rainfall, coupled with other bioclimatic conditions of the tropics, has yielded a

high plant density in the island.  Biomass therefore, is available in plenty.  Since

Sri Lanka is located in the equatorial belt, it receives a year round supply of

solar irradiation.  The tropical temperatures and the islands location in the

ocean have resulted in distinct wind regimes. These settings have endowed the

country with an ample RE resource base.

Some of these RE resources are widely used and developed to supply the

energy requirements of the country. Others have the potential for development

when the technologies become mature and economically feasible for use.

Following are the main RE resources available in Sri Lanka.-

Biomass-

Hydro Power-

Solar-

Wind

Sri Lanka’s power sector is heavily dependent on hydro power. We have been

developing hydro power since a long time back. All these hydro schemes were

major power generation projects and they are also known as ‘conventional’

power generation schemes since they have been around for quite a long time.

Now however, the capacity of such large schemes is nearing their end.

Therefore we have to resort to other means of generating power, among which

the grid connection of small hydros, wind power generation schemes and solar

projects are receiving much attention. Such technologies are termed non-

conventional renewable energy (NCRE) technologies, because they were not

used in the past in conventional grid power generation.

 This page is under construction. The illustrations will be installed as soon as possible. 

Sustainable Energy Resources in Sri LankaBy

Ananda D. MoonasinghaIntroduction             Sri Lanka is an island in the Indian Ocean located near the South Eastern tip of India. Sri Lanka does not possess any fossil fuel resources. Power generation is largely by hydropower constituting approximately 61 per cent of the grid supply and the rest from imported fossil fuels. About 1 percent of grid supply is by small scale renewables of mini-hydro, wind and solar. Largest energy consumption by sector is cooking amounting to about 42 per cent of which 90 per cent is derived from biomass.           The global energy consumption is largely dependent on utilisation of fossil fuel resources. The climate change ascribed to anthropogenic emission of carbon dioxide from global energy consumption is a major concern of the global environmental agenda. Whilst natural gas is the least harmful fossil fuel, research and development of clean coal technologies are advocated for the utilisation of much larger potential resources of coal. Environmental impact assessment is a part of the process of improving sustainability of development.            Whilst in Sri Lanka a large proportion of the country’s major hydropower sources have been harnessed, small-scale renewables such as mini-hydro, solar, wind power, bio-gas and energy conserving improved stoves for cooking are being promoted by programmes of

sustainable energy systems. In the energy sector the conventional definition of appropriate technology is less pertinent. The solar power which is a high-tech technology is appropriate for electricity generation in some remote communities in developing countries. Country Profile            Sri Lanka is an island of 25,000 square miles/65536 square kilometres in area in the Indian Ocean near the South Eastern tip of India. It has a population of just over 19 million and a literacy rate of 92 per cent. The per capita income in 2007 was $4100. Approximately 80 per cent of the population live in rural areas (Wind energy, SGP, UNDP).Salient statistics in 2007 suggest 34% of the working population are engaged in agriculture, 27% in the industry and 40% in services. Unemployment rate in 2007 was 6.3% (CIA fact book).            Energy consumption by sector in 1999 is in the order of: Household 42.5%, Transport 27%, Industries 20%, Lighting 7% and other 3.3% (IDEA). The composition of total energy resources in percentage basis is Biomass 54%, Generated power %, Non-commercial renewable % (Fig. 1). 

Fig. 1. Composition of Energy Resources             The total installed power generation capacity is approximately 1838MW. The grid based power infrastructure system is run by the Ceylon Electricity Board (CEB) a state owned monopoly. The composition of power generation is made up of 62% hydro, 37% thermal and 1% renewable comprised of mini-hydro plants and a 3MW pilot wind farm (Tyndall). Investment in power generation lags behind the annual demand growth of 8-10% (Tyndall, Collarado, Nagendran, Fernando). Approximately 61% of the households are supplied by the grid electricity system. Electricity supply system is characterised by shortfalls in capacity of generated power resulting in poor reliability of supply to domestic customers, manufacturing and service sectors (Colorado). Off grid small-scale electricity supplies comprise about 5MW  capacity of village hydro schemes and nearly 1000MW of photovoltaic units.           Sri Lanka does not possess any fossil fuel resources of oil, coal or natural gas. The fossil fuel resources imports cost approximately 15% of the export earnings (IDEA). In 2004 the amount of petroleum imports increased by 44% and constituted 15% of the total import bill resulting in a large trade (exchange) deficit (Colorado). At least part of the land area of Sri Lanka is well endowed with a good average annual rainfall and surface water resources. The South West quadrant known as wet zone comprising the coastal planes and central hills rising up to 1500 m receive an annual average rainfall of 2000 mm in the low lying border regions to 5000mm in the central hills enabling significant hydropower potential. More than half of this hydropower potential in the form of major hydropower plants has been harnessed. However, as generally known annual rainfall can vary significantly, and in dry years hydroelectricity is unreliable and the grid supply has to depend on imported fossil fuel generated power supply. Energy Resources             Energy sources may be classified in to three broad categories (Soussan, PRE). 

1. Commercial fuels: oil, coal, gas and electricity including large-scale hydropower.2. Traditional or biomass fuels: wood, charcoal, crop and animal waste.3. Renewable alternatives: wind, solar, mini-hydro, biogas, thermal, wave and tidal power.

           Energy efficiency and conservation are also key variables in the sustainable energy formula.            Renewable energy can be defined as energy obtained from perpetual sources that may occur continuously, repetitively or cyclically in the form of currents or flow in the natural

environment or certain states of biomass that may be regenerated in the natural environment by the action of man. (RES – JT&TW, ). Examples are solar, hydro  wind and biomass. Another definition given by Sorensen is cited as ‘energy flows which are replenished at the same rate as used’.(RE,Boyle)            Non-renewable energy is energy resources obtained from finite static deposits on earth. Examples are fossil fuels of coal, oil and natural gas, and nuclear power. These are generally known as commercial fuels. The definitions of renewable and non-renewable energy are rather deductive, hence like all meanings, are fluid. Energy Utilisation and Environment            Consumption of fossil fuels discharges greenhouse gases, mainly carbon dioxide (CO2). Burning coal also discharges sulphur dioxide (SO2) and nitrogen oxides (NOx) to the atmosphere causing acid rain and atmospheric pollution. Gases that absorb radiation of waves longer than 4μm are called greenhouse gases, because they absorb most of the thermal radiation reflecting from the earth’s surface and heat the atmosphere (IEES,GMM). This is a natural phenomenon that keeps the global temperature at a favourable range to sustain life and natural environment on earth. Anthropogenic emission of greenhouse gases has shown to increase the greenhouse effect that disturbs the global climate. Global warming ascribed to increased carbon dioxide emission to atmosphere from anthropogenic fossil fuel consumption is a topical challenge in the global agenda that pervades across numerous domains of the society such as economics, politics, development, technology, environment and social well-being.            In the last decades of the 20th century the concern of environment regulation in Europe was to decrease and control the emission of SO2and NO2. To this end and in compliance with European Economic Community (EEC) Large Combustion Plant Directive, in 1992 flue gas desulphurisation plant was retrofitted at the Britain’s largest coal-burning Drax power station. (NP). The most widely applied technology for reduction of SO2 emission is Flu Gas Desulphurisation (FGD) (Longhurst, 1989). In the flue gas desulphurisation process, ground limestone mixed in water to produce limestone slurry is sprayed on to the flue gas in a vessel to absorb SO2 from the flue gas. In the early phase of the absorption process reaction between calcium carbonate of limestone slurry and SO2 produces calcium sulphite. Then the oxidation of calcium sulphite by the air forced into the absorber vessel produces slurry of gypsum. This slurry is then dewatered to give the by-product gypsum, a widely used building material (NP).           The other means of reducing SO2 emission from coal-burning power stations are: using coal containing low sulphur and new combustion techniques such as fluidised bed combustion.            In the 21st century the concern is over the emission of CO2 contributing to the phenomenon of global warming and climate change. Methane, produced in landfill sites and in farming activities, and the main component comprising about 95 per cent of natural gas is also a potent green house gas. However, natural gas when burned for instance in a power generating plant it could reduce the carbon emission by about 42 per cent compared with a coal-burning plant (IEES,GMM). Natural gas is by far the most environmentally favourable form of fossil fuel.           Chlorofluorocarbon (CFC) used as refrigerants in refrigerators, freezers and air-conditioning systems are other greenhouse gases. Use of CFCs has been reduced after the worldwide controls of the use CFCs for nonessential applications such as in aerosols (IEES,GMM). Nitrogen oxides (NOx) are usually emitted in the form of nitric oxide (NO) which is harmless. However, under adverse conditions when nitric oxide (NO) oxidises to nitrogen dioxide (NO2) in sunlight reacts with hydrocarbon and may contribute to the formation of photochemical smog, which can cause respiratory illnesses. NO2 can also contribute to acid rain (IEES,GMM).

            Transportation sector is responsible for high percentage of emission of NOx and the highest emission rate of carbon monoxide (CO) in the urban environment. Almost all emissions of CO in transportation come from motor vehicles, especially heavy vehicles (IEES,GMM). Sustainable Development 

United Nations in 1987 adopted the definition of sustainability or sustainable development as, ‘development that meets needs of the present without compromising the ability of future generations to meet their own needs’ (Energy Systems and Sustainability, OU & Oxford; Our Common Future).            Herman Daly has prescribed the following conditions of sustainability (Kaya, p33, EEE).            (a) The consumption rate of renewable resources is not higher than its recovery rate,            (b) The consumption rate of non-renewable resources is not higher than the rate of increase in renewable resource supply,            (c) The emission of pollutants is within the absorption capacity of the environment.                         In the context of energy, sustainability has been defined as the harnessing of those energy resources: (ESS, OU-Oxford)            (a) those are not substantially depleted by continued use,            (b) the use of which does not entail the emission of pollutants or other hazards to the environment on a substantial scale; and            (c) the use of which does not involve the perpetuation of substantial health hazards or social injustices.             The above accounts especially the last definition virtually encompass the connotations of sustainability comprehensively, though not exhaustive implicitly. In a complex world of trade, politics, economics, poverty, supply and demand, skills, culture and the like influence the energy harnessing and consumption; there are other notions that impinge on sustainability. Some of these can be summarised as follows.            (a) Ability and economic feasibility of the user and supply communities to operate, repair and maintain infrastructure systems,   particularly the energy systems to function in an optimum capacity.            (b) Ability of the energy importing nations to continue to do so and efficiently distribute the wider energy resources among the diverse communities living in different geographic regions of a country.            (c) There is an efficient allocation of resources and efforts for integrated function of infrastructure systems as well as other entities like communities, economics, safety and health, law and order, finance and commerce. Appropriate Technology             Appropriate technology broadly signifies: a method or technique that involves low capital cost, low investment cost per work place and unit output, organisational simplicity, adaptable and provides a service or quality acceptable to a particular social or cultural environment at least economic cost, uses local materials available where ever possible, energy efficient, creates jobs employing local skills and labour, can be understood, controlled and maintained by local community, matches the need in complexity and scale, and improves the quality of life (Kalbermatten et al – 1980, Carr – 1985, Hazeltine and Bull – 1999). Most of the above factors tend to compromise with quality and convenience, and requires regular maintenance. As an exception appropriate technology does not have to be necessarily low-cost or low-tech, provided the community can pay for the capital and long-term service costs, and maintenance

(USAID – 1980, Kooi in SRDTW Editors Southgate & Disinger). Particularly in the energy sector photovoltaic electricity is high-tech resource used in remote villages in Asia and Africa. Small-scale wind turbines are less high-tech than photovoltaic, but requires an effective local maintenance base (Kooi – SRDTW). In general the developing societies have a technological base for the operation and maintenance of the technological assests (USAID – 1979). However, Kooi describes the importance of the strengths and effectiveness of local maintenance base of mechanical utilities like wind turbines for the sustainability of small-scale renewal energy systems in the developing world (Kooi – SRDTW).            There is no unique definition of appropriate technology to serve all purposes (Kalbermatten et al -1980). Though the account in the above paragraph preponderates the definition of appropriate technology the appropriateness of technology should be assessed on its ability to fulfil the prioritised needs of the users and to economically facilitate its functional purposes. To stipulate desired criteria of appropriate technology it is necessary to confine it to community infrastructure in the nature of small-scale rural utilities and of low-income communities. In this context appropriateness of conventional infrastructure such as highways, bridges, power stations, dams and major irrigation systems and even photovoltaic energy has to be measured in a different scale. Appropriate technology for developing countries should be:             (a) economically affordable,            (b) able to be built or installed by country personnel with minimum need for imported skills,            (c) and be able to operate and maintain by country personnel.            Other conditions corollary of the foregoing criteria are: the local people can be trained locally or nationally according to their abilities and basic educational achievements to meet the demand of the labour and skills supply including the technical and managerial skills. Management and workers understand, and are committed to adhere to sustainability criteria of the appropriate technology. In the energy sector, like civil engineering, technology that does not comply with the scientific and engineering principles to an optimum degree, do not sustain.            Appropriate technology is the application of technological abilities based on scientific knowledge for the satisfaction of the needs of a community in its own culture and natural environment using appropriate management and organisation methods enabling the group to start, maintain and continue the production of their goods and services (Riedjk – AT for DC). In a later definition Riedjk transcends the above ideology aiming for local autonomy: appropriate technology is aimed at the production and application of the tools; organisational arrangements, technical provisions and self-management, self-sufficiency and self-development (Riedjk – p10AT for DC).            Though the latter is a noble goal, in reality from the writer’s inference in the public sector thoughtless, uncanny localisation of technological management and skills in large projects tends to create chaos and impoverishment of appropriate technological services and reliance on recurrent central and external funds for sustainability. The cycle of decentralisation and when the things appear to get out of order the tendency for centralised supportive control is known as accordion effect (Mc Gregor). Culture evolves. Culture and technology shape each other. Technology depends on culture for its sustainability and a change of culture in particular of management. Environmental Impact Assessment (EIA)            Adverse impacts form part of the costs of energy utilisation. Hence environmental impact assessment has become a mandatory element of planning process of major power and transportation projects and other industrial activities.            Environmental conservation laws have existed in Sri Lanka during the colonial times and even in the customs and edicts in the ancient civilisations. With the growing worldwide

awareness and interests in the environmental impacts since 1970s, institutional enactment for the environmental impact assessment was established in the 1980s decade (Zubair-EIAR, Yasaratne – CEA). The implementation of environmental impact assessment process basically comprises two phases of Initial Environmental Examination (IEE) and the Environmental Impact Assessment (EIA) report. The Project Approving Agency having reviewed the IEE determines whether an EIA report is necessary. The administration structure comprises the Central Environmental Authority (CEA) and more than 10 Project Approving Agencies (PAAs) who review and approve the environmental reports. The PAAs include the CEA, several pertinent Ministries and few other state authorities. A schedule of Prescribed Projects stipulates the requirement of need to comply with the environmental impact assessment process. Public participation by the affected communities, NGOs and other interested agencies is facilitated in the scoping process since the submission of the IEE and following the receipt of the EIA (Zubair-EIAR, Yasaratne-CEA) The preliminary review determines whether an EIA is necessary. Scoping resolves what key impacts, issues and alternatives to be considered (Therivel & Morris p4, Mof EIA. PM &RT). The breadth and depth of study components can vary to a great extent in different projects in different locations depending on the significance and weighting of each component and its impacts. A key objective of an EIA is to mitigate the adverse impacts.            Environmental impact assessment is usually regarded by the developers as a burden adding to the project costs. In the developing countries especially where the entrepreneurship and industry is less developed, implementing the EIA process poses challenges and weaknesses (Zubair, Kodituwakku, Mackee et al, Romaya & Rakodi-BSUS). However, in Sri Lanka in the energy sector the Prescribed list does not require an EIA for renewable energy projects of less than 50MW and fossil-fuel power project of less than 25MW capacity. This absolves virtually all small-scale energy projects from the EIA. The impacts of a hydropower project less than 50MW can be significant.            In general the environmental impact assessment encompasses human, terrestrial and aquatic environments (MEIA). These embrace, socio-economics, health, security and social well-being, aesthetics; pollution control, soil conservation; protection of archaeological sites, water quality and resources, flora and fauna and the like. In Sri Lanka EIA of major dam projects constructed in the recent past have created national parks, wildlife sanctuaries and nature reserves. The most controversial element of dam projects is the displacement of people, villages and towns. In Sri Lanka most people displaced have been resettled in irrigation schemes. Market values of properties lost have been compensated and measures have been provided for the removal and resettlement (Moonasingha IWEM 1991). The amount of financial compensations and living conditions of the settlers have been criticised by the opponents (Soussan.J – PRETW). In the recent development projects even more generous compensation terms have been granted.            In the monitoring phase of the EIA a key observation for instance is shortage of fuelwood for cooking. There are obvious weaknesses in irrigation projects to mention a few: poor maintenance resulting in rapid dilapidation of field infrastructure and poor management of irrigation. Coconut palm is a versatile crop plant that provides multitude of invaluable produce like firewood, timber, roofing, utensils and cultural art décor besides its food and drinks products. It is ironic that irrigation settlement communities suffer firewood shortage, because coconut is the traditional plantation in highlands. However, shortage of forest and timber resources in colonisation schemes is a serious issue that needs to be redressed by reforestation of scarce village reservations. Institutional Support            Multilateral and bilateral aid plays a significant role in small-scale renewable energy development and sustainability programmes. Major power projects have been sponsored by these sources in the past and will continue to do so to some extent. A number of small-scale

environmental improvement projects such as forestry, biodiversity, soil conservation and renewable energy projects have been sponsored by the Global Environment facility (GEF), a facility under the auspices of the United Nations Development Programme (UNDP), World Bank and other agencies. The success of these small-scale community projects up and down the country testify that communities in Sri Lanka can be motivated and organised with the right vision, management techniques and institutional support to implement appropriate technological projects. A suggested barrier to sustainable energy development is the indifference of central and provincial governments to small-scale renewable energy technologies, and reliance on grid supply and fossil fuels, which represents the general stance of the society (IDEA). Inadequate legal environment for private sector distribution to mini grid is another barrier (Nagendran).The Non Governmental Organisation (NGO) ‘Sarvodaya’ is a pioneer and leading promoter of rural development projects in Sri Lanka (Sarvodaya, GVEP). Governmental Organisations (GOs) and local NGOs in collaboration with international agencies, counterparts such as Intermediate Technology Development Group, and private entrepreneurs develop and promote sustainable energy projects. The National engineering Research and Development (NERD) Centre and Integrated Development Association (IDEA) are prime public sector organisations promoting sustainable energy technologies.            Financing, micro-credit, appropriating and commodifying the technology, and capacity building by facilitating the training and technical support are prerequisites of disseminating small-scale renewable energy systems (IDEA and Nagendran). Besides the benefits of clean, safe lighting, small-scale renewable energy schemes generate various other socio-economic benefits. Energy Resources in Sri Lanka             Renewable energy resources exploited to different scales in Sri Lanka are: hydropower, biomass, solar and wind power (IDEA; Ekanayaka; UNDP& Govt.SL). The fossil-fuel resources of oil, coal and gas are imported sources. Currently, in spite of the larger installed hydro capacity, considering the effects of dry years nearly half of the electricity supply is generated by imported fossil-fuels. Besides a significant supply from photovoltaic (PV) units, the projected future growth of power supply is poised to come mostly from thermal plants using imported fossil fuels (Wijayatunge et al-UN). 38 per cent of energy consumption has been accounted for cooking with biomass or firewood (IDEA). Fuelwood and energy conserving improved woodstoves are important components of sustainable energy resources (Fig.2) (Amarasekara; FAO). Energy saving fluorescent light bulbs and building technology, demand management and devices like hydraulic ram pump are other important components of sustainable energy strategy. Biogas produced from cow dung and straw is a thriving renewable energy source. Dendro power from burning fuel wood and wood gasifier stoves are other small-scale pilot projects explored. Improved stoves and combustion technologies for commercial activities like bakeries and kilns add to the list of innovations in sustainable energy drive. Large number of households uses rechargeable batteries for lighting and television. Households without any form of electricity or other form of renewable energy use kerosene for lighting. The potential of tidal power is insignificant. The potential of wave energy is significant but unlike photovoltaic, wave energy technology is not yet commodified for dissemination in the developing countries. The barriers to expansion of the use renewable energy resources are mainly, limited information on the potential of particularly the small hydro and solar; limited familiarity and confidence of these technologies; and shortage of skilled personnel to install and maintain these technologies (UNDP-Govt. of Sri Lanka). The large number of photovoltaic solar panels installed by domestic consumers and private sector suppliers is an indication of amelioration of technology assimilation and capacity building in this sector. 

   

              Pictures with the courtesy of IDEA 

Fig. 2. Energy Conserving WoodstovesBiomass             Biomass is organic matter of plants and animals (Twidell & Weir). It is the organic carbon based material that is useful to produce energy. Biomass may be present in various forms such as, fuelwood, straw, crop fibre, animal waste and sewage sludge.            Fuelwood for cooking is the predominant use of biomass for energy. Another important source of biomass for energy is biofuels such as methanol, ethanol and biogas. Aerobic and anaerobic digestion of biologically degrading biomass produces biogas composed mainly of a mixture of CH4 (Methane) and CO2. Domestic biogas production is well developed in India and China. In industrial processes such as in sewage treatment works heating the digester within mesophilic range 30-40 0C and thermophilic  50-60 0C temperature range increases the methane yield and decreases the detention time of the substrate in the digester (USNAS- EinDW). In India the standardised design of biogas plants using cow dung as biomass requires at least 5 heads of cattle to install a satisfactory domestic biogas plant. (Chaman

Kasshkari – Biogas plants in India. ibid). In Sri Lanka there are some 3000 biogas units in operation mostly built by private sector. 80 percent of units use cow dung and others are batch type digesters using straw. (Pract Action, S MunasingheIDEA, Biogasdisk7).            The most rudimentary cooking fire is three stone fire which is inefficient (Practical Action). The traditional stove built in the kitchens is energy saving than the basic three stone fire. Traditional kitchen built with a chimney or ventilation holes expels smoke contributing to smoke related ill health. Improved cooking stoves manufactured since 1970s have an energy efficiency of 21 percent and firewood saving in average of over 30 percent. The improved cooking stove can make a useful reduction of CO2 emission from about110 to 260kg/CO2/capita/year (Amarasekara-IDEA). Hydro and Mini Hydro Power             Hydropower constitutes a major portion of the installed capacity of grid electricity supply. Hydropower stations are built to operate at their full capacity when the reservoirs are sufficiently full. However, hydro reservoirs do not fill to their capacity every year and are subjected to the cycle fluctuating cycle of yield in the river flows. The installed capacity of biggest hydro plant is 210MW. The major sources of hydropower potential in Sri Lanka have now been virtually harnessed. Grid connected mini-hydro plants of size 1MW and off-grid village hydro schemes of capacity range 3-50KW are being introduced. Hydro plants between 10 kW and 200kw are defined as micro hydro plants (Khennas & Barnett). It is estimated that about 340 off-grid village hydro plants are in operation in Sri Lanka (Fig.2) (Nagendran, VillageHydro-IDEA-inforse, HandsonTV). Towards sustainable energy resources, Sri Lanka will have to accelerate the pace of harnessing the remaining hydro power resources. A disadvantage of hydropower resource is its full capacity is not available constantly due to dry seasons and years. Hydropower also competes with land resources where a part of the population is vying for land for a homestead allotment.  

   

 © Peter Crawford / Practical Action

  Fig. 3.Village Mini-Hydro Plants Photovoltaic Energy             Photovoltaic (PV) power generation is a sophisticated technology based on photovoltaic or solar cells made of silicon (Si) crystals. The manufacture of solar cells involves complex and precision operations. However photovoltaic cells are designed to rigorous standards and mass produced to a minimum cost, to have a minimum life of 20 years and to withstand conditions reasonably expected in the remote areas of developing countries. The ordinary PV cells have an efficiency factor of 10-12 percent of total incident insolation (Twidell & Weir p167, p162, SESCI ).            In Sri Lanka the average solar insolation in most parts of the country exceeds 5120 watt hours/m2 per day. Photovoltaic is the largest off-grid source of electricity (Fig 4) (IDEA). Nearly

100,000 households are installed with PV electricity units with a total capacity of nearly 1000MW (Sarvodaya). The potential for PV as renewable energy is significant, limited only by the socio-economic factors such as awareness, micro-credit and capacity to satisfactorily install and service a large volume of customers especially in the remote areas of the country (Nagendran). Large customer potential also has the advantage of scale. A disadvantage of PV energy is it is diurnal and needs a storage battery for 24 hour power. Wind Turbines             Wind energy is an excellent source for generation of electricity with an efficiency of around 95 percent. However there is a minimum limit of useful wind speed for turbine operation which is about 5 m/s or 4 in Beaufort scale (Twiddle & Weir, ). In Sri Lanka only few locations experience wind speeds that is suitable for operating wind turbines. These sites are in coastal regions in the South, North West and North and one in the central hills (Wind Atlas-Colorado, Dunnett-ITDG). A pilot project of 6 wind turbines at 12m height, each of 250kW capacity has been extended to more than 25 turbines in the Hambantota district in the South coast. The cost of a wind turbine is slightly cheaper than a PV unit(sgp.undp.org, Young & Vilhauer). Like other small-scale renewable energy systems wind turbines require a storage battery that can provide a service of charging batteries of other households during excess generation periods. Fossil Fuels                Imported fossil fuels will play a major role in energy utilisation in Sri Lanka in transport and power generation (Govt. SL). Power sector will use imported coal and gas. Combined Cycle Power Gas power stations are efficient and less polluting. Coal power stations are responsible for emission of SO2 and greenhouse gases. Modern technology can filter most of the dust pollution from coal power stations. Thermal pollution by cooling water discharged into nearby waters is an important factor that has to be considered in protecting sensitive marine environments. Fossil fuel  power plants do not displace families or towns. However, local people are concerned about the problems of pollution. Conclusions             Sustainability in reality is a relative term that dictates an onus for responsible development and energy utilisation. Sustainability is compromised to an extent that countries have to resort to using fossil fuel, especially coal for power generation. In Sri Lanka the proliferation of small scale renewable energy sources, hydro, photovoltaic, biogas, wind, improved stoves, reforestation, energy conserving lighting and building technology, and demand management are the key instruments of mobilising sustainable energy strategy. This endeavour has several facets of development benefits. These are: capacity building, motivation, generation of industrial and commercial opportunities, poverty alleviation, strengthening regulatory and legal enabling environment, planning, financing, procurement, private enterprise, and environmental improvement. Photovoltaic energy has significant potential to contribute to sustainable energy strategy encompassing reduction in emission of greenhouse gases. Education, training, motivating and organising community resources to underpin the sustainable energy resources strategy is a principal goal. It is important to safeguard the community based appropriate technology developments from a culture of decadence and impoverishment. Because of the shortfalls in the grid supply and poor reliability of supply, small-scale renewable sources are desirable as a backup source for some domestic, industrial and public energy consumers.

Biomass

 Solar