After years of talk, 2010 has seen a number of farm based AD plants actually commissioned. However according to David Wright of independent renewable energy advisers JHWalter, we will see significantly more farm-based plants installed over the next two years. “We are fortunate enough to have been working with those considering AD for many years now, and our first thermophilic plant in the East Midlands has just started commissioning. Based on the number of prospective AD projects that we are advising on across the country, it is clear that those who have been watching from the sidelines, are now ready to take projects forward”.

There is no one ideal situation for AD, and the drivers vary from energy security to waste management to “straightforward ” commercial investment. Whilst the question of how FIT rates were calculated remains a frustration, finding alternative investments with guaranteed income streams at reasonable yields is difficult. However whilst some of the headline theoretical returns can look attractive, there are many practical and technical issues to address, not least the affect on the existing farm business, to ensure a successful outcome. “An AD project includes a plethora of factors, many of which are interrelated – change one and several others will be affected. It is vital that the overall specification provides the best fit in terms of the farm’s operation and also meets the original energy objectives. Issues of feedstocks, site location, grid, biomethane options, land use, digestate handling etc all relate to one another” comments Mr Wright. “Experience and an open mind to all possibilities helps to bring together the optimal scheme”

There is inevitably some confusion with the number of technology suppliers increasing all the time and with specifications and claims varying to a lesser or larger degree. That is where JHWalter’s experience and independence comes into play. The company can advise from the very initial scoping of a project through specification, planning, permitting, project management and installation. Unlike some JHWalter have seen firsthand the technical and economic consequences of a variety AD models. Opportunities to optimise capital expenditure and consideration of overall returns as opposed to specific component efficiency levels are all taken into account in both initial design and specification.

Heat utilisation is an important element of the overall project. JHWalter schemes include a variety of uses including drying, district heating (commercial and domestic), and heat absorption cooling. Whilst a project can “stack up” without heat utilisation, the economic and environmental credentials of the scheme are much improved when a use can be found.

Funding is of course central to such projects but the view of JHWalter is that capital costs are beginning to fall. There are inevitably still concerns over FIT rates and the grant issue. “There is some great work being done by the REA and CLA on these issues which we continue to support. Hopefully this work will improve overall financial returns. However for many of our clients, a slightly longer payback is deemed reasonable given the longer term gains.