Stirling engine microCHP given green light by exemption from costly new grid connection rules

The industry welcomed Ofgem’s decision to publish a Guidance Note to the Distribution Code that effectively gives certain Stirling engine based micro combined heat and power (mCHP)- a capacity constrained and time limited exemption from the requirement to operate over the frequency range set out in ER G83/2.

The decision acknowledges that mCHP  using the Stirling engine as a prime mover has been designed using resonance to operate within ±1% of the nominal frequency of 50Hz. Accordingly it is not technically possible for generation using this technology currently to remain connected down to 47.0 Hz as required by G83/2. For it to comply would require major re-engineering of products that have taken considerable investment to develop, and have only recently come to market.

Recognising the limitations of the current technology, and noting that currently the adoption of this technology is developing, the Distribution Code Review Panel stated that G83/2 tests relating to operation at frequencies outside the ±1% range should be waived or modified, thus allowing this technology to continue its niche use.

The industry would like to thank the Energy Minister, the Energy Networks Association, the Distribution Code Review Panel and Ofgem for their constructive engagement during the past few months in reaching this sensible conclusion.

Dave Sowden, Chief Executive of the Micropower Council, commented: “The Stirling engine mCHP is the only technology available on the market as a straight-forward domestic gas boiler replacement that offers meaningful CO2 and fuel bill reductions. It made no sense to to drive this product from the market before it had time to establish itself.

Graham Meeks, Director of the Combined Heat and Power Association, added: “Next week mCHP will become the only technology to receive an increase in support from the Feed-in-tariff.  Exempting this fledgling technology from onerous regulation, albeit on a time limited basis, is a very welcome development, and shows the continuing Government support for mCHP.

Roger Webb, Director of the Heating and Hot Water Industry Council, said: “MCHP offers real potential for householders to reduce their energy bills and their carbon emissions. This is a very welcome development which overcomes a significant hurdle for Stirling engine driven mCHP.”