Biomass CHP: Gasification

Learn about gasification in the context of Biomass CHP, the typical outputs and costs and the pros and cons of gasification.

Back to: Biomass combined heat and power (CHP)

What is gasification?

In the context of biomass CHP, gasification is the process which converts biomass into a flammable gas, suitable to power an internal combustion engine. The engine is used to drive a generator for the production of electrical power. Gasification systems are typically relatively small-scale, with a ratio of heat to electrical output usually in the region of 2:1.

It is extremely important that combustion of the biomass fuel produces clean gas for the engine, so this type of biomass CHP will normally require a clean fuel source, such as wood pellets.

Typical outputs and costs

Electrical output	Heat output	Indicative cost	Tonnes of fuel per day*	Fuel
50 kW	100 kW	£200k	1.3	Wood pellet
100 kW	200 kW	£400k	2.6	Wood pellet
1 MW	1.4 MW	£3m	21	Wood chip
2 MW	2.8 MW	£6m	41	Wood chip

*24 hour operation

Pros and cons of gasification

Pros

Highly incentivised through government subsidies
Reasonably scalable for smaller applications
Small footprint
High electrical–heat ratio
Can provide high-temperature usable heat up to 250°C
Large-scale gasification units can be configured to run on recycled timber

Cons

New technology with few reference sites
Small gasification units can only run on the best-quality, and therefore more expensive, wood fuels
High maintenance costs