Thermal processes typically combust waste to heat water to drive a steam turbine. This is inherently inefficient and offers only the possibility of on-site power and heat generation. Gasplasma® is different. The process overcomes the challenge of producing a synthetic gas from waste which is capable of being used directly in gas engines, gas turbines and fuel cells, thereby achieving greater electrical efficiencies. Moreover, the gas, which comprises the basic building blocks of all organic chemistry, has many other applications such as conversion to hydrogen, substitute natural gas (methane) or to liquid fuels.
Instead of ash, the Gasplasma® process produces a vitrified product which is strong, inert and environmentally stable, with a number of end use applications. Importantly, the material is a product and not a waste and can be used in the construction industry. It has very low leaching characteristics.
The syngas produced by the process is highly calorific and can be used directly in gas engines and gas turbines to generate power more efficiently than in steam cycle systems. As fuel cell technology advances, the syngas will also be capable of being used, directly or indirectly, in fuel cells to generate power. The table below gives an indicative breakdown of generating efficiencies.
|Power Islands||Electrical Conversion Efficiency (%)|
The process also produces heat which can be used in a number of ways depending on the particular requirements. Excess steam can be used in the fuel preparation and drying process within the plant itself or can be used to generate more power. Surplus heat, for instance from the power island, can be exported for any nearby heating requirements. The process meets Good Quality CHPQA requirements in terms of efficiency.
The syngas can be converted efficiently into substitute natural gas (essentially methane) for injection into the gas grid. APP has undertaken a project in the UK with National Grid plc and Progressive Energy to design a residual waste to substitute natural gas (SNG) process and to demonstrate production of SNG at its Swindon facility.
The syngas produced by the process already comprises around 40% (by volume) of hydrogen. Much of the remainder of the syngas can be converted into hydrogen by conventional water gas shift to enable the production of pure hydrogen at a community scale on a highly competitive basis. Hydrogen will have an increasing role to play as a fuel particularly as a transport fuel in fuel cell electric vehicles and to supplement natural gas in the gas grid.
The syngas comprises hydrogen and carbon monoxide, the basic building blocks of all organic chemistry. It can be converted easily through a variety of different commercially available processes to liquid biofuels such as ethanol.