The world’s first power plant producing electricity and heat using crude jatropha oil as fuel is to be built by Wärtsilä in the agricultural area of Merksplas, in Belgium. Wärtsilä has secured the r7 million order for the prime mover, a diesel engine that will run on a liquid biofuel that is extracted by pressing the seeds of the jatropha plant. Commercial operation is scheduled to begin in February 2009.

The plant will be owned by Greenpower NV, which is a joint venture between Thenergo (50%), the Belgian developer of sustainable energy projects, four local agricultural companies (40%), and a private investor (10%). Greenpower and Wärtsilä have signed a letter of intent for a 10 year O&M agreement.

‘Jatropha oil is a liquid biofuel that has great potential since the plant can be harvested outside the world’s rainforest areas, even in near-deserts. It is a step towards using CO2–neutral fuels that do not compete with other valuable food crops’ says Ronald Westerdijk, a Wärtsilä business development manager.

Adapted diesels

Under this turnkey contract, Wärtsilä will deliver the CHP plant which is centred on a 20V32, 750 rpm engine providing an electrical output of

8.92 MW. This is one of the range of V engines (20, 32 and 46) adapted by Wärtsilä to run on liquid biodiesel made from clarified vegetable oils, such as palm, jatropha and olive, without further treatment before firing. By the beginning of this year the company had sold 700 MW of this kind of engine for power plants, including ItalGreen Energy’s 24 MWe unit in southern Italy which employs 3x18V32s, produces steam at 10 bar for heating and is the largest of its kind in the world.

The gross electrical efficiency of the Merksplas unit will be 44.2 %, slightly less than the 46% specified for the same engine using regular fuel. 8.5 MW of heat will be supplied in the form of hot water at 38°C. The scope of supply also includes exhaust gas cleaning equipment and the heat recovery systems. In its CHP mode the plant will have an overall efficiency greater than 85%, which will result in the avoidance of more than 36 000 tons of CO2 production per year.

The plant’s heat output will be used mainly for horticultural purposes, in nearby greenhouses. It will also be used in a drying process that is part of a livestock farming manure digester plant that processes biogas and dry fertiliser material. Electricity will be sold to the grid.

Jatropha – a versatile fuel

Thenergo’s strategy is to diversify its feedstock base, namely biogas, natural gas, bio-oil, woody biomass and secondary fuels. For the past five years it has been researching the sustainable potential of the jatropha plant, a large bush or small tree whose ‘seeds’ are a non-edible, high-energy fruit grown on semi-arid or waste land. The tree has a productive life of 35 to 50 years and can yield between 0.5 and 12 tonnes of fruit per year per hectare, which produces on average 1600 litre/ha of oil. Although not a food or forage crop it plays an important part in providing a barrier to cattle, to protect other food and cash crops, and its seed can also be used in the manufacture of soap. The pressed residue of the seeds is a good fertiliser and can be burned as solid fuel for electricity and heat production.