3MW Hambantota
winds plant

Renewable Energy includes energy produced by resources that are constantly replenished and will never run out. There are many forms of renewable energies. The basic forms include hydro, biomass, wind, direct solar energy and geothermal energy.

In contrast, petroleum, coal, nuclear and natural gas are classed as non-renewable energy resources. These forms of energy, which are consumed by the present generation causes rapid depletion of resources (except nuclear energy) denying the accessibility of the future generation to its usage.

Sri Lanka is renowned for its richness in plant diversity. This richness is interpreted in terms of the number of plants in a unit area (density) as well as the variety of plants. The high density makes it possible to extract vast quantities of plant mass (biomass) from a given plot of land. It is estimated that approximately 40 billion kg of biomass can be generated by converting all marginal land (1.6 million ha – one fourth of the total area of Sri Lanka according to available records) to fuel wood plantations and improving productivity of other crop land and homegardens. Total potential of this resource is estimated to be 15 million toe (all energy forms are converted to a common unit of tonnes oil equivalents – toe for ease of comparison) per annum. Biomass is the most widely used renewable energy in Sri Lanka, accounting for more than 50% of our primary energy even today.

(i) Solid biomass, which are either raw fuel wood or a processed form of agro or animal waste such as fuel briquettes, paddy husk…etc. This is the most widely used energy form in Sri Lanka, accounting for more than 50% of the total energy consumption

(ii) Liquid biofuels – known as biocarburants in an engineering perspective – which are alcohols and oils derived from either tree or animal sources. These commodities are produced in large volumes, even at present, but used for other purposes apart from energy sources.

(iii) Gaseous biofuels, commonly known as biogas, which are combustible gases emanating from rotting biomass, due to a process known as anaerobic digestion. A small number of households use this energy form, converting animal droppings and agro waste into a valuable cooking fuel.

Biomass energy can be produced in comparatively large quantities in Sri Lanka, where a lot of rainfall, plenty of sunshine and a fertile soil all combine to yield remarkable quantities of biomass in a given area within a very short period of time.

The amount of solid biomass extractable on a sustainable basis is around 30,000kg / ha per year in Sri Lanka, in contrast to most other countries, where yields are mostly around 10,000kg / ha per year. Further, our dry and arid zones like the typical Puttalam and Hambantota areas are actually quite wet by the standards of other countries, based on their annual average rainfall. Hence in essence, Sri Lanka is rich in biomass resources.

The Government has already recognised the need to elevate biomass as both a commercial crop as well as the third fuel option for electricity generation. Following this realisation, the government also declared Gliricedia Sepum (Known as Weta Mara, Ladappa, Ginisiriya) the fourth plantation crop after tea, rubber and coconut in 2005. Further, plans are underway to replace 20% if transport fuels with biofuels by 2020, and therefore prospects for biomass energy in Sri Lanka can be termed as bright.

Sri Lanka is endowed with a rain-fed central hill zone, nested in a perfect geographical setting that renders the country with a good hydropower potential. The country has used this resource for conveyance of irrigation water for many millennia, and for electricity generation during the last two centuries. The early days of grid electricity generation saw hydro as the major component in electricity generation, accounting for more than 65% of the total. Recently, this component has been reduced to 35% mainly due to the exponential load growth, which no longer can be met by this limited resource.

However, significant portions of small hydro potential still await development. Potential sites have capacities ranging from a few hundred kilowatts to about 40 megawatts, and the total potential is estimated to be around 500 MW. Thus, total energy potential that can be realised by developing this portion stands at 1,500 Giga watt hours (GWh) per annum or 0.13 million toe per year.

Sri Lanka is also blessed with ample sunshine. From earliest times, this resource had been utilised for drying crops and clothes, and has remained largely a non-commercial energy resource.

Two thirds of the country’s lowland areas receive a radiation of 4-5.5 kWh / m2 per day, whilst the remaining area in the central hills receives a lower radiation of 2-3.5 kWh / m2 per day, due to persistent cloud cover in those areas. It is interesting to compare these energy yields with daily electricity consumption of a typical household as both are in the same range of 4-5kWh per day. However, it is dangerous to assume that all houses can be provided with a solar panel of one square metre, as conversion losses (in excess of 80% even with the latest technologies) and energy storage requirement of such a system position this technology well beyond the affordability of a typical family. Cost of a solar solution comparable with a CEB grid electricity connection is closer to LKR 4 million, and the cost of a unit of energy thus produced will be more than LKR 70 per kWh, much more expensive than a unit of energy supplied by CEB.

Solar photovoltaic technology has come forward to provide basic electricity to isolated and sparsely populated areas of the country, with successful initiatives by both the CEB and the NERD Centre. Presently, the technology has reached a high level of commercialisation, with installed capacity reaching a 3.5MW level, with approximately 110,000 solar home systems, and a few pilot scale grid connected plants. The Government readily approved a proposal prepared jointly by the Sustainable Energy Authority, LECO and CEB to allow willing consumers to erect solar PV power generator on their rooftops, to export electricity during day time and consume during night and only to pay for the ‘net’ amount of electricity drawn from the grid. This concept of ‘net metering’ will be offered to the Sri Lankan electricity consumer shortly.

The potential of this resource is usually not quantified, because the only limiting factor is land area. However, a significant amount of energy can be harnessed using solar thermal technologies for commercial heat applications as well as for power generation applications. The size of the resource can be approximately visualised based on a generation capacity of 20MW, utilising 430 ha of land area which can generate 25 GWh, roughly a days electricity need of the country.

Sri Lanka is located in the Indian Ocean facing a vast swath of uninterrupted ocean, which provides her with substantial wind energy potential. The country experiences two main wind climates, namely the southwest monsoon (May-August) and the northeast monsoon (October-December). The earliest records of utilising wind energy in the country trace its roots back to 300 – 200 B.C. Archaeological evidences explicitly suggest that iron was smelted in the Balangoda slopes in the contemporary period, harnessing wind power from the southwest monsoons. Sri Lanka is the earliest country to utilise wind energy for an industrial purpose.

As in the case of hydropower, wind energy is derived from a moving body of wind, by transferring the kinetic energy of the moving body of wind to a turbine rotor. Due to the very low density of wind, (water is nearly thousand times denser than air) the devices needed to harness wind energy are essentially enormous structures, usually having rotating components with diameters exceeding 100 m.

The wind resources, estimated after a meso-scale study by the National Renewable Energy Laboratory of US, with the CEB under a technical assistance programme of USAID, stands at 25,000 MW. Only 3 MW of capacity of this vast, renewable resource is presently exploited. The most promising area identified is the west coast. Further ground wind assessments are underway to develop this resource to a commercial level. The total potential of this resource is estimated to be around 40,000 GWh. Only a minute portion of this capacity may be developed, if Sri Lankan grid remains isolated from a stronger regional power grid, as in the case of European wind havens such as Germany and Netherlands which are connected to the massive coal / nuclear powered European Grid.