Tomorrow's energy story...  today

The challenge to move energy production from fossil to renewable is enormous. "An area half of Wales will need to be filled with wind turbines to produce 50% of energy needs", is a familiar statement. Building barrages across the Severn, installing tidal turbines and other major projects all feature in a drive to move away from the coal, oil and gas. 

Bio-gas production captures fewer headlines, despite it being independent of weather, inexpensive to construct and much less visibly intrusive than the wind turbine. Farmers can construct their own bio-gas plant to provide a 'free' source of fuel to heat the house, run the Aga and provide hot water for farm use in the dairy. Bio-gas can be used as part of the fuel in a standard diesel engine. Energy savings from a relatively small plant will have a value up to £10,000 a year.

This Practical Farm IDEAS feature describes a bio-gas digester which works on 100% cow slurry, heated with the surplus energy from a wind turbine and also solar panels. It uses slurry from 70 dairy cows on a 200 acre farm. The total value of energy is equal to approx £7,000 a year of oil and electricity at farm gate prices, or £100 per cow. This is before any incentive payments such as ROCS.

The potential for farmers is considerable

Bio-gas has the advantage over wind and has the potential to become another reliable income stream. This is already happening in Germany and other continental countries, but we have found none that realise the value of integrating wind turbine energy with gas production - the value of effectively smoothing out the intermittent power of the wind and multiplying this by generating the gas.

Most production systems have waste products that need disposing, yet the waste from this digester is actually a better fertiliser than the fresh slurry which goes in, and it is stored in exactly the same type of lagoon as any other slurry. The processed slurry is free of ammonia. When he spreads it there are no seagulls flocking to catch the worms which normally surface, because the worms aren't starved of oxygen (they're normally coming up for air, and so make a ready meal for the gulls). The N in the processed slurry is slowly released.

Some pictures from the Farm IDEAS report:

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