AMID the upheaval now gripping the UK's system of green energy incentives, farmers and landowners considering installing biogas technologies have been advised to "reconsider their options".

With heat-based tariffs rising but support for farm-scale electricity generation on the wane, manufacturer Norvento is advising aspiring biogas producers to analyse the economics of their energy consumption before committing their cash to combined heat and power machines.

Speaking at last week's All-Energy event in Glasgow, Norvento's UK director Ivo Arnús said that, for many businesses, heat-only Anaerobic Digestion technology might now present a more viable opportunity than more expensive systems that also produce electricity.

Just as new medium-scale wind energy installations in the UK were shifting their focus away from exporting power for profit and towards on-site consumption, Mr Arnús reckoned that biogas users will find that using energy on-site provides the strongest business case for installing a renewable energy system, particularly where heat, rather than electricity, is central to supporting intensive on-site production processes.

Dairy and pig farmers stand out as ideal users of heat-only AD plants, he suggested, because not only do they generate substantial waste products to use as AD fuel, they also rely on heat-intensive processes on-site.

“Heat-only AD systems, optimised to match energy demand, are already proving their worth for rural industries throughout Europe," said Mr Arnús. "By way of an example, Norvento has installed one of its BioPlant AD systems at a cheese factory in Spain, where there is no financial incentive scheme in place, but returns are highly attractive.”

He stressed that this did not mean heat-intensive users should ignore the potential to generate electricity on-site to meet their other energy requirements, or for export at a profit to the grid – it was simply that they should properly balance consideration of their own energy use and assets before committing.

In the short term, the emphasis for these potential users must be on analysing how energy produced by an on-site system can be best used on site to guarantee a swift return on investment. Norvento's own estimate is that a 600kW heat-only plant that costs around £600,000 to install can have an annual gross income of around £200,000 and a payback period as short as 3.5 years – providing all the heat it produces is used on site.

This compares to the installation of a CHP engine at the same plant, where, with 50% of the power produced consumed on site and 50% exported to the grid, capital costs would increase by £250,000 and the payback time would increase to nearly 5 years.

Currently, heat needs to be consumed on-site as there is no means of ‘exporting’ excess heat to a district heating grid, unlike the electricity produced by a wind turbine or CHP plant. However, with substantial funding being announced for innovative local ‘heat networks’, a number of pilot projects are underway that are projected to further incentivise the installation of heat generation plants on farms and rural businesses bordering towns.