Green electricity from biomass fuelled producer gas engine

Abstract

In the recent times issues like the Green House Gas (GHG) emission reduction and carbon-trading through Clean Development Mechanism (CDM) have gained large prominence as a part of climate change. Biomass gasification is one such technology which is environmentally benign and holds large promise for the future. These technologies are currently being utilized for power generation applications at a number of industrial sites in India and abroad. In India there are nearly 4 MWe equivalent power plants which are based on IISc's open top reburn down draft biomass gasification technology. In the field of power generation, there has been substantial effort in the development of producer gas engine; systematic experimental and modeling studies followed by long duration field monitoring. As a part of this effort, a gas carburetor has been designed for producer gas fuel and forms a part of the power package. The essential requirements of gas conditioning equipment are packaged to meet the engine quality gas as a power plant. Currently there are more than 3.0 MWe equivalent gas engines operating in the field; of this one is deployed in an Energy Service Company (ESCO), which sells green electricity to a textile industry. The company is located at Metupalyam in South India, near the city of Coimbatore. The power plant is configured with a 150 kg/hr gasifier coupled with a turbo charged after cooled Cummins make (GTA855G) gas engine. The plant is also provided with an effluent treatment plant and an engine-waste-heat based biomass drier. The plant commissioned in September 2003 has successfully completed over 7500 hours of operation, generating about 0.7 million units, thus saving a net CO₂ of about 0.7 million Tons against a fossil fuel technology. The plant operates on a continuously to meet the end use requirement over 275 hours non stop operations hours of operation. The power plant utilizes a weed namely Julifora Prosopis which is abundantly available in the southern part of India and converts into green energy; additionally generates value added product namely partially activated carbon-Iodine no. of 400-450. The paper reports specific biomass consumption and engine emission monitored over long duration. The specific biomass consumption is measured to be within 1.1 ± 0.1 kg/kWh with an overall efficiency of 22-24%. It is also found to be environmentally benign in terms of emissions; NO_x and CO levels are found to be much lower than most of the existing emissions norms of various countries including the United States and European Union. The paper also highlights results from other installations using this technology. Keywords: open top gasifier, producer gas engine, CDM technology.