[Gasification] Better use of biofuel crops?

[Ken Boak]

List,

About 70% of the UK land area is under agriculture, totalling approximately 
18.5 million hectares.

http://www.defra.gov.uk/environment/statistics/land/kf/ldkf05.htm

Of the approximate 4 to 5 million hectares under crops, there is between 500 
and 800 thousand hectares that are set-aside land.

If  500,000 hectares of set-aside was turned over to biofuel production,  it 
could provide sufficient fuel for 400,000 cars, each averaging 12,000 miles 
per year.

With improvements in biofuel yield, selection of improved crops,  and using 
gasification to obtain additional energy from the agricultural residues, it 
might be possible to produce enough biofuel from UK crops to fuel 1 million 
passenger vehicles, or approximately 4% of the vehicle population.

However, the poor overall efficiency of the IC engine, when used for vehicle 
propulsion, means that much of the energy content of the biofuel is lost as 
waste heat.

The alternative to liquid fuels is to use short rotation coppiced willow, 
for co-firing our existing coal fired power plants.  Again, the overall 
efficiency of this is low, with only 30%  to 40% of the fuel energy reaching 
the end use.

Not wishing to disrupt existing agriculture and local food production,  the 
use of forestry land, once used to supply the paper pulping industry and now 
fallen out of management, and set aside land could be brought back into 
management for the growing of wood for bioenergy.

500,000 hectares planted with short rotation coppiced willow or poplar could 
supply 5GW of electricity in conventional thermal power generation plant. 
(at 100 hectare per MW of electrical output).  This is about enough to 
supply the likes of the largest Drax power plant, that currently supplies 
about 7% of the UK electricity

Drax has been conducting trials of co-firing using SRC willow since 2005

http://www.power-technology.com/projects/drax/

However, neither automotive biofuel nor co-firing thermal power plant 
appears to make the most efficient use of this fuel source.

Recent trends for distributed generation, district heating and co-generation 
have shown that better use can be made from the otherwise wasted heat.

Most of these schemes tend to be in the >1MW size (100 homes) rather than 
the 10kW  (single home) power output, generally because of the problems and 
costs associated with biomass mechanical handling and the bulky storage.




Ken