Sri Lanka is an island with much rural poverty and no fossil fuel reserves. The solution to its energy needs lies with its indigenous biomass resource, write L.P. Jayasinghe and P.G. Joseph, some of which can be utilized in decentralized cogeneration installations.
Sri Lanka is a low energy intensity country, averaging only 0.39 tonnes of oil equivalent (toe) per capita (hydro power, petroleum and biomass fuels) and ‘commercial’ energy intensity of 0.16 toe per capita per year. ‘Commercial’ refers to marketed energy and excludes biomass fuels as most of these are not ‘purchased’ by users (such as fuel wood collected free of charge). These values apply to all sectors (household, commercial, industrial, transport) in Sri Lanka. ‘Commercial’ energy use is also low, at an annual electricity consumption of 322 kWh per capita and an annual petroleum consumption of 160 kg per capita.
Rice husk, a valuable by-product of rice production, can be used as biomass fuel. Biomass already meets nearly half of Sri Lanka’s energy demand (© WWF-Canon /Adam Oswell)
Nearly half the primary energy demand in 2003 was met using biomass, and 40% from imported petroleum fuels; the balance was met through indigenous hydro resources (see Table 1). Energy consumption in 2003 by the different sectors is shown in Table 2. Energy flows in Sri Lanka in 2003 are summarized in Figure 1.
Figure 1. Energy flow diagram for Sri Lanka (in thousand toe)
|Total primary energy||9122||100%|
|Domestic, commercial, other||3807||51%|
The Ceylon Electricity Board is the state-owned utility responsible for the generation and transmission of electricity in the country via the national grid. It estimates that consumption will grow at approximately 7%-8% each year for the next 5-10 years. An additional 120-150 MW per year will be required to meet this demand.
Sri Lanka’s social, environmental and economic problems
Thermal generation, whatever the fuel may be, is the only viable option to meet the predicted future demand for energy. This leaves Sri Lanka with a grave financial crisis if this thermal energy is to be obtained from imported fossil fuels.
The value of the Sri Lankan rupee against the US dollar has declined considerably since the 1980s, while successive Governments have concentrated on export-based economic growth to earn more foreign exchange. The option of reducing the outflow of foreign exchange to import essential commodities, including the country’s fuel requirements, has not been adequately examined. Developing indigenous energy resources to meet the nation’s needs would relieve the demand for foreign currency to import fuel.
Rural-urban imbalance in economic growth
Over 40% of the population are classified as living below the ‘poverty line’. The Government spends over 10,000 million rupees (US$100 million) annually to provide relief to these families. Many of these communities are from rural areas where agriculture and fisheries are the main economic activities.
Over 70% of the population still resides in rural areas despite the migration of vast numbers of the people to the urban areas of Western Province, where most of the industrial development in the past few decades has been concentrated. Western Province accounts for 40% of national gross domestic product (GDP) growth.
The development of indigenous energy resources in the rural areas of Sri Lanka would conform to the shift in policy by the newly elected Government to develop the country’s rural locations.
Lack of proven fossil fuel reserves
Sri Lanka imports all its requirements for fossil fuels. The ever increasing prices of fossil fuels, particularly petroleum fuels, have adversely affected its economic development. In 2005, petroleum imports cost a total of $1636 million – more than the total export value of agricultural produce of $1154 million. Expenditure on imports of petroleum products accounted for 26% of the total export earnings of $6347 million. The high values of petroleum imports have imposed significant strains on Sri Lanka’s balance of payments.
According to the Survey Department, over 1.6 million hectares of land area in Sri Lanka is classified as ‘scrubland’ (i.e. land degraded by the unsustainable agricultural practice of shifting cultivation by the ‘slash and burn’ method). This is over 25% of the country’s total land area of 6.2 million hectares. Moreover, there are indications that the extent of scrubland is increasing due to greater pressure on such land from the rural agricultural community. Some of these lands may have already been so severely degraded as to initiate the process of desertification.
There is an urgent need to find a suitable technology to reverse the process of land degradation in Sri Lanka. Sustainable energy plantations in these degraded lands could provide substantial income to the rural agricultural communities, thus alleviating poverty while reversing the degradation process.
The energy scenario is deteriorating throughout the world. Non-renewable resources are being rapidly depleted with consequent environmental and economic damage. According to current estimates, all known reserves of oil, natural gas and uranium will be exhausted within the next 50 years and coal within the next 250 years. On a more positive side, solar energy and biofuels offer considerable potential for the supply of both electrical and thermal energy. Water movement (providing hydro power) and photosynthesis are abundant, environmentally responsible and free.
Renewable biomass has recently attracted fresh interest as a source for electrical energy due to its potential as a low-cost indigenous supply of power and for its environmental and developmental benefits. Biomass conversion is seen as one option for reducing the build-up of carbon dioxide (CO2) in the Earth’s atmosphere. Local environmental benefits can include reduced soil erosion, restoration of degraded lands and amelioration of local impacts from fossil-fired power generation. For developing countries, renewable biomass energy systems can offer a number of social benefits from employment to entrepreneurship.
Solar, wind and hydro resources in Sri Lanka
From the point of view of electricity generation, the country’s hydro power potential is around 5000 GWh per year with a peak power of 2000 MW. Of this, around 1300 MW have already been developed, and these power plants are generating a little over 3000 GWh per year. There are plans to develop the remaining potential within this decade.
Sri Lanka has a hydro potential of 5000 GWh per year (Grid-Connected Small Hydro Power Producers Association)
A study based on satellite data conducted by the US National Renewable Energy Laboratory (NREL) revealed that Sri Lanka’s onshore-based wind power technical potential is over 24,000 MW. About 1% of this could be targeted for immediate development. Offshore potential is much larger. Although the amount of energy that could be generated per megawatt of wind power potential is low, the total energy generation potential through wind power is substantial in Sri Lanka.
Wind power will play a significant role, with a large generation potential in the offshore sector (Ceylon Electricity Board)
Solar thermal energy
Solar thermal energy is widely used in Sri Lanka for household, commercial and industrial applications such as crop drying and salt manufacture. However, this form of energy utilization is not included in national energy consumption statistics; there are practical difficulties in estimating the actual energy consumption in such activities, which do not use any devices or equipment.
Solar home systems are popular in Sri Lanka – they provide electricity to 10% of the ‘off-grid’ population (Shell Solar)
The use of solar thermal-based water heaters has recently been commercialized. These devices are now installed in many households and commercial buildings, saving substantial amounts of electricity and fossil fuels that would otherwise have been needed to produce hot water.
Being a tropical country located near the Equator, Sri Lanka has enormous potential to harness solar thermal energy, particularly for low- and medium-temperature applications. The use of solar thermal-based high-temperature applications, particularly electricity-generation systems, is also being considered by some energy planners.
Solar photovoltaic systems
Solar home systems (SHS) consisting of a solar photovoltaic (PV) panel with an output of 35-100 W and integrated controller, charger and battery systems are very popular in Sri Lanka among the ‘off-grid’ community (households located away from the national grid). Around 120,000 households are currently provided with SHS – some 10% of those not connected to the national grid. Although solar PV SHS is considered expensive, its simplicity in terms of operation and maintenance makes it the most practical option for households located too far from the national grid to be connected.
The national grid currently supplies 77% of the population with electricity, but the Government is considering connecting at least 80% of households within the next five years. At least 85%-90% of households are expected to eventually receive grid-connected electricity. This would leave 10% or nearly 500,000 households to be served with off-grid systems. Its high cost means that, realistically, only half these households are expected to be served with SHS.
In 2003 biomass energy accounted for 48% of Sri Lanka’s total primary energy. Most of these biomass fuels are derived from sustainable sources such as rubber plantations, coconut plantations, cinnamon cultivation, bagasse from sugar industries, rice husk from rice mills and domestic gardens. In addition, dedicated energy plantations have also been established by some of the plantation industries such as tea. A small quantity of wood comes from illegal extraction from natural forests.
Localized energy production will provide many social benefits for Sri Lanka (Shell Solar)
The Department of Agriculture, the Coconut Research Institute and the Ministry of Science and Technology have carried out extensive trials on short rotation coppice (SRC) plantations with nitrogen-fixing trees planted on degraded lands. These studies suggest that Gliricidia sepium (GS) trees are the best species for such areas. Mature branches of GS could be harvested at regular intervals. Coppice wood from a hectare of SRC plantations with GS would yield, on average, 30 tonnes per year of dry wood and 26 tonnes per year fresh foliage in a sustainable manner.
Based on the results of these trials, action has been initiated to convert such lands into sustainable SRC plantations with a closed canopy all year round. Woody parts of the coppice branches are sold as fuel wood to energy conversion facilities. Foliage from these branches is rich in nitrogen fixed by the trees and is used as cattle fodder or directly as organic fertilizer for agricultural crops such as coconut and rice.
The study conducted by the Ministry of Science and Technology revealed that nearly 1.6 million hectares of land remain degraded and under utilized in Sri Lanka. These degraded lands could be converted into sustainable SRC energy plantations with GS. The total amount of biofuels that could be generated from these plantations is 48 million tonnes per year. This is equivalent to 12 million tonnes of oil and could be used to generate an equivalent of 30,000 GWh of electricity per year.
This is nearly eight times the hydro power potential in Sri Lanka and four times the total annual electrical energy presently consumed. In other words, if the biomass energy resources are developed, it would be possible for Sri Lanka to be self-sufficient in terms of electrical energy for many years to come.
Part of the biomass fuels generated from sustainable energy plantations could be utilized to generate industrial process heat – preferably through cogeneration. Biomass fuels could also be utilized to meet refrigeration needs through absorption technology. Such decentralized generation of energy would improve the overall energy efficiency of Sri Lanka. Biomass-based fuels (bioethanol, biodiesel and biomethane) to meet the transport needs of the country are also being considered.
Indigenous energy resources
One could say that all forms of energy that utilize indigenous resources could be classified as ‘indigenous energy resources’. But when we consider the plight of Sri Lankan economy (particularly the need to minimize the drain on foreign exchange while maximizing its inflow), it is clear that the primary issue is not the physical source that should be considered but the need to examine the entire process of converting the resource into useful energy.
Although the source of energy for a solar PV system is the sun, which may be considered indigenous, the actual cost involved in generating electricity by solar PV is essentially ‘foreign’. The solar PV panels and storage batteries are imported. So are the electronic devices such as the regulator. When one calculates the cost of generating electricity by solar PV, it becomes clear that most of the cost is attributable to imported components. A similar result is obtained with large-scale wind power plants unless at least some components are manufactured locally.
On the other hand, most of the cost of electricity generated from biofuels is encountered in the production, transport and processing of the fuel. In this case, a large share of the cost of generation of electricity is incurred in local currency within the country. Hence one could say that biomass-based electricity generation is largely indigenous.
Definition of indigenous energy
This leads us to the definition of indigenous energy. A practical means of classifying an energy source as indigenous or not is to assess the final total cost of that energy. If more than 50% of the total cost can be attributed as local costs, then such energy could be classified as indigenous energy.
All forms of energy derived from locally produced biomass would thus easily qualify for being an indigenous energy. Small-scale wind power plants and small-scale hydro power would also qualify as indigenous because such plants do not require any fuel incurring foreign expenditure. The substantial cost of constructing them is also incurred locally.
Merits of indigenous energy
The social, economic and environmental pressures facing the people of Sri Lanka mean that the following benefits could be achieved by developing indigenous resources:
- Conservation of foreign exchange. The drain on foreign exchange would be minimal as a major share of the cost of generating energy comes from domestic sources. This would result in less demand for foreign currency in Sri Lanka and the parity rate of foreign currency would be favourably placed. This in turn would reduce inflation and hence the cost of living for a large section of the population.
- Poverty alleviation. Development of indigenous energy resources would provide an opportunity to infuse economic growth into neglected rural areas and particularly the poorer segment of the agricultural workforce. Unemployed people could be deployed in energy plantations, the construction of mini-hydro power plants, etc. A large share of the value added in such activities would enable the income levels of the poor rural communities to rise above the poverty level, allowing them to live without having to depend on government handouts.
- Energy security. Sri Lanka’s lack of any proven fossil fuel reserves means that the development and utilization of indigenous resources for energy generation would improve its energy security. As the country is blessed with enormous amount of indigenous renewable energy resources, it could become totally self-sufficient in energy, thus achieving energy independence. This would benefit Sri Lanka enormously, allowing it to improve its balance of payment problem and alleviate the economic downturn resulting from heavy escalation in the cost of energy experienced recently.
- Reversing land degradation. Establishment of sustainable energy plantations in the degraded lands would enable these areas to be converted into a stable and productive environment with improved biodiversity. The heavy soil erosion resulting from repeated slash and burn would also come to an end.
Different countries in the world need to adopt different energy policies to match the differing needs of their respective countries. A policy of ‘indigenous energy’ is appropriate in Sri Lanka, a country facing severe strain on its foreign exchange, with rural poverty and lacking any proven fossil fuel reserves. The socio-economic and environmental features prevailing in Sri Lanka make indigenous energy resources very cost-effective. Many other countries should perhaps also examine the adoption of such a policy.
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Biomass energy utilization
The medium-voltage (33 kV) electricity distribution network spreads extensively across Sri Lanka. The network has penetrated all inhabited locations of the country excluding protected areas such as forest reserves and wildlife sanctuaries. Plans have been drawn up to connect another 5%-10% of households to the national grid (77% are currently connected) within the next five years.
The gases generated at a coconut shell charcoal manufacturing plant are combusted in a boiler and the thermal energy harnessed to generate electricity
The first set of biomass-fired power plants will be less than 5 MW in capacity. This limit has been chosen in order to gain experience in managing the supply chain of wood fuel requirements for such plants. A 5 MW biomass-fired power plant would require 180 tonnes of wood per day. The land area required to generate this quantity of wood in a sustainable way would be 2000 hectares (i.e. the area needed by the 16 million trees required, spaced 1 metre x 1 metre apart). In practice, such land would consist of many blocks of land, each not exceeding 20 hectares; the trees will be planted on vacant land and will grow among other trees and crops. Assuming that the ‘energy’ trees occupy 25% of the land and the other trees occupy the rest, the ‘catchment’ area would need to be 8000 hectares (i.e. 2000 x 4). The spacing required by the trees means that they will occupy a circle of diameter 10 km, i.e. they will be planted within a 5 km radius of the power plant.
The plants could be interconnected with the national grid at the 33 kV medium-voltage level. The maximum distance of any inhabited location in Sri Lanka to the medium-voltage line is less than 10 km. Hence it is proposed that the first batch of biomass-fired power plants should be located within 2-3 km of the 33 kV distribution network.
The actual location of the proposed power plants will depend mainly on the proximity to the associated plantations and the 33 kV network. Other factors such as availability of land to build the power plant, adequate storage area for the fuel wood, and the availability of adequate cooling water also need to be considered. A land area of 2 hectares would be needed for the power plant and storage. The water requirements for a 5 MW plant would be 40 m3 per hour (make-up water for the boiler and evaporative cooling towers). Experience suggests that such quantities of water could be obtained from a groundwater source.
Although the potential exists to optimize biomass-based electricity generation with industrial heat applications through combined heat and power (CHP), such applications would be limited to around 25% of heat energy presently generated by the industrial sector. Sri Lanka’s industrial sector currently used 2 million toe of fuel (biomass and petroleum) annually to produce heat energy; 25% would amount to 0.5 million toe.
Part of the electricity generated is used on-site and the rest exported to the grid. The project is able to sell the carbon credits resulting from both methane abatement and fossil fuel saving
It would be possible to deploy CHP technologies such as back-pressure steam turbine or extraction of waste heat from internal combustion engines operated using petroleum or biomass gasifiers. A total of 1600 GWh of electricity could be generated by this technology annually, i.e. 20% of the electrical energy generated at present.
There are a number of reasons why it is not possible to use CHP to generate the other 75% of industrial heat.
- High-temperature applications. The brick, tile, ceramic and cement industries in Sri Lanka require high-temperature heat for processing. Use of CHP systems is not feasible in such applications.
- Very low plant factor. Some agricultural-based industries operate on seasonal basis for limited months of the year. Moreover, such factories operate for only around 8 hours per day. Hence the annual plant factor of such operations would be around 20%, making it uneconomical to incur additional expenditure on CHP equipment.
- Time variations in the heat and power demand. In some applications such as the tea industry, daily requirements for heat and electrical energy occur at different times of the day. If CHP was applied, it would be necessary to store either the heat or electrical energy and recover and use it later in the day. The electricity utility in Sri Lanka does not permit wheeling, banking or net metering features, although a two-meter system for buying and selling electricity is allowed.