Turning household rubbish into electricity is viable, efficient and economical, according to a new venture in the bio-energy sector.
Using a unique combination of new-generation alkaline fuel cells with plasma gasification and other existing proven technologies is the key to increasing efficiency and affordability, says the company, Waste2Tricity, that is backing the scheme.
The firm has been launched to bring the latest technology to market, with the aim of becoming the most efficient converter of municipal solid waste (MSW) into electricity.
The conversion of MSW into power has not yet been adopted on a wide scale because of its low efficiency, fears over emissions and waste from incineration or from existing gasification systems.
Waste2Tricity is planning to develop community or business-scale plants to turn household or commercial waste into a hydrogen-rich gas that can be used to generate electricity on site.
The company will use new-generation fuel cells that will increase the net output of electricity by a minimum of 60 per cent over an internal combustion engine generation system, or by 130 per cent over a steam turbine system.
The fuel cells are designed to be of low-cost construction, with 90 per cent of all components being made from standard engineering plastic, and are low cost to maintain. The company estimates that the price of generating electricity can be fewer than three pence per kilowatt hour (kWh) at February 2008 prices (100 pence equals one pound sterling).
The planned process involves a Waste2Tricity facility that will take in sorted carbon waste – plastics, paper, cardboard, food and other plant material – and convert it into electrical power.
The waste will enter a plasma gasification chamber and be turned into syngas – that has 50 per cent the energy density of natural gas – by the application of very high temperatures (more than 6,000 degrees C).
This process has advantages over incineration in that fewer pollutant gases, tar, ash and fly ash are produced. The main by-product, vitrified slag, is inert and can be used as aggregate for road building.
Waste2Tricity’s plans to build its first waste-to-energy pilot plant were given a boost recently after the company secured an exclusive agreement with AFC Energy, an innovative producer of low-cost, new-generation fuel cells targeting waste hydrogen in commercial applications.
Waste2Tricity is in negotiation to secure the agreement of a number of strategic partners to proceed with its first 50,000-tonne pilot plant, representing stage one of its programme – combining plasma gasification with internal combustion engines to generate electricity.
At stage two, hydrogen cleaning and alkaline fuel cells will be substituted for the internal combustion engines, greatly increasing the efficiency of the system. On successful implementation of the pilot plant, the system can be replicated and has worldwide potential.
Waste2Tricity says the AFC fuel cell will have a far lower manufacturing carbon footprint than existing rare earth substrates, and stored electricity becomes ÒportableÓ without the need for expensive national grid investment. The stage one plant could be ready within three years with stage two in operation in four to five years and it is estimated that about 22,500 homes could be powered by one plant.
The environmental benefits include:
- a reduction in landfill and therefore reduction of emissions of greenhouse gases such as methane from that source;
- a potentially more efficient form of electricity generation in terms of reducing carbon emissions;
- the main by-product, inert slag, can be used as an aggregate;
- the facilities can be built on existing landfill sites so that existing infrastructure such as roads built for waste transport can be used.
There are about 35-40 million tonnes of biomass sent to landfill in the UK each year, of which Waste2Tricity believes it could initially process about 20 per cent that would be capable of generating some 2,100 kWh of electricity from every tonne of waste sent to landfill.