Woodfuel can be used to generate both electricity
and heat. CHP plants generate electricity whilst also capturing the
usable heat produced in this process and can be up to 90%
efficient.
CHP is more efficient than in power-only plants where heat
energy is lost. Most biomass power plants use steam produced by
combustion to drive turbines which generate electricity. However,
electricity generation alone generally has a low conversion
efficiency (30% to 45%) - a significant proportion of the energy is
lost as 'low-grade' heat.
CHP plants work well where there is a constant large heat load,
such as UPM Caledonian Paper in Irvine and Balcas' pellet plant in
Invergordon
CHP is also suitable:
- When there is a requirement for space heating or process heat
close to the generator
- To provide low temperature (up to 90 degrees C) hot water
heating for local district schemes
- For applications that require (low grade) process heat,
especially those that can supply their own fuel (i.e. sawmills and
wood process industry which use heat for timber drying and
steaming)
- At sites such as hospitals, leisure centres, greenhouses, and
retirement complexes which have a year round heat demand
- To provide steam for other industrial applications
- Where there is a requirement for environmentally responsible
disposal of waste (i.e. sewage sludge, clinical waste or
agricultural residue) and where transport costs for disposal are
high
- To power an absorption refrigerator to provide cooling in
summer, giving tri-generation.
The Scottish
Renewables Forum publishes a regular update on all
large-scale renewable energy projects in Scotland and their
status.