Sunday, September 20, 2009

Maximising the Value of Sewage Sludge Biogas - Study Reports

The September 2009 edition of the Newsletter of UK Water Industry Research Limited, leads by reporting on their study into "Maximising the Value of Biogas". We thought that it contains some really interesting pointers to those involved in planning and running Anaerobic Digestion facilities, so we report on it in this posting.

Biogas has for some time been employed by the UK Water industry as a source of energy for combined heat and power plants.

The employment of biogas becomes more attractive as advances in technologies for biogas production, treatment and application, mixed with new financial inducements for various kinds of renewable energy progress. Optimisation of biogas production and use will also bring ecological benefits, including helping the water industry mitigate its global warming impacts.

The UKWIR project Maximising the value of Biogas, managed by Gordon Wheale, gives a clear appraisal of the technologies and the expenses concerned in maximising the earning potential of biogas produced from the digestion of sewage sludge.

It inspects the advantages stemming from biogas optimisation and possible 'regulatory blockers'.

At an UKWIR project dissemination workshop, representatives heard from James Newton of the contractor, Mott MacDonald, the technology needed for conversion of biogas to biomethane is well established and commercially available.

Conversion of biogas to biomethane makes accessable all of the applications of natural gas including injection into the nation's gas grid or use as an automobile fuel.

Such uses are well established in mainland Europe and a number of states around the world. While technically possible, there are not many examples of sewage biogas being converted to hydrogen ( for combustion or use in fuel cells ) as these are typically extremely expensive both in term of capital and operational costs.

With new developments in hydrogen technology, this will (they expect) become an enticing option in the future.


This research discovered that the use of biogas for CHP generation for on-site use would, usually, achieve the best worth for a water company. CHP is a mature technology with proved commercial benefits and the best systems can convert up to forty percent of the energy contained in biogas into electricity.

The utilization of biogas as a fuel for autos also achieves a comparatively high worth and, in some circumstances, higher than that achieved for biogas CHP. It also brings ecological benefits compared to standard fossil auto fuels.

Sensitivity of the values that can be derived for different biogas uses is found to be extremely variable arising from only minor changes in guesses. They found that in particular, the values of the renewable energy drivers available ( which in a few cases are still to be established by secondary regulation ) and the impact of the 'Carbon Reduction Commitment' gave big changes in value.

Also they are sensitive to site explicit factors. These include the supply of biogas for other uses, the leftover cost of existing investments in CHP assets and the distance to the local gas grid. So a site explicit survey should be carried out when thinking about alternative biogas applications.

The research for this report reveals that different biogas uses can have broadly similar values. Therefore , for many sites, optimizing biogas production may achieve larger financial and environmental advantages than changing the output use."

For further information get the September Edition of their Newsletter by using the link below:

No comments: