Agricultural Use of Anaerobic Digestion for Livestock Manures and Slurries
Probably the most authoritative recent study on the viability of anaerobic digestion is the report prepared for the Sustainable Agriculture Strategy Division of the United Kingdom Department for Environment Food and Rural Affairs (DEFRA).
The report is titled, ‘Assessment of Methane Management and Recovery Options for Livestock Manures and Slurries’ and is available for download from DEFRA’s web site (Report number AEAT/ENV/R/2104).
It should be noted that the report is dated October 2005 and that since then world oil prices have risen by 15 to 20% (January 2007).
The study’s, authors looked in detail at the economics for options for on-farm AD and centralised AD (CAD) in England, and their conclusions follow:-.
All the options proved uneconomic without some extra Government support.
However, a small number of larger CAD may be economic, especially if higher levels of industrial waste (up to 20%) were treated in the CAD.
A cost benefit analysis based on the options and assuming Government support in the form of capital grants suggests that greenhouse gas emissions equivalent to up to 0.03MtC could be saved annually at a cost of £60/tC, if 20 CAD plants were built. However, this would result in lifetime costs to Government of £143M.
On-farm AD would need significant support to be economic.
The authors therefore found that the main challenge to Anaerobic Digestion in the UK is therefore still an economic one.
An example of Agricultural Biogas Plants on Dairy Farms.
Furthermore, they were of the view that even for CAD (which is more economically viable they say, than on-farm AD, high capital costs and that an uncertain supply chain and market for products gives rise to high levels of project risk.
A combination of actions involving financial incentives and engagement with farmers and technology suppliers would be needed to stimulate the market.
The experience from Germany suggests the main route to market for on-farm AD is to set incentives at a level such that it becomes a recognised source of extra income for farmers.
Their analysis suggested very strongly that this will be an expensive option - for Livestock Manures and Slurries.
So, it does have to be considered that the dawn of the significant adoption of AD for Livestock Manures and Slurries is still some way off.
Our view at Anaerobic-Digestion.Com is that there is a very good case for additional government investment in on-farm AD.
There is a significant win to be found from the reductions in greenhouse gas emissions, and the necessary £143 lifetime costs estimated for the first twenty plants would surely deliver big bonuses in the development of the technology. If done well this investment would act as the seed corn for the mature development of the AD industry at which time costs would surely plummet.
Were we not at a similar stage with wind turbines no more than ten years ago?
Surely many of us can remember that wind turbine rotor blade failures featured heavily in the news. The doubters were saying that the reliability problems being experienced in that industry at the time were close to insoluble for such highly stressed and massive blades. Yet now who even mentions such problems?
The parallels are all around us which show us the benefits of strategic investment and the potential in AD. Let us see some leadership from our politicians who should by now realise that the public demand for action on carbon emissions is high.
The public also increasingly want to buy renewable power for their own domestic use, and so the provision of financial incentives for AD would help in this and other many ways.
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