Kingston: an organic Rankine cycle microCHP for the UK

Developers of microCHP technology are hoping to be among the beneficiaries of the UK government’s new feed-in tariff for small scale low carbon electricity, which came into effect on 1 April. Under the sceme, microCHP units with a capacity below 2 kW will receive 10 p per kWh generated, over a period of ten years, plus an additional export payment of 3 p per kWh for electricity not used in the home and exported to the grid. The tariff is available for the first 30 000 microCHP installations, with a review of the scheme to take place after 12 000 installations.

One such microCHP developer gearing up for future installations in the UK is Energetix, which in March unveiled its “Kingston” organic rankine cycle (ORC) based microCHP unit.

The Kingston microCHP unit is designed to generate 1 kWe of power, which can be utilised in the home, with any excess not used exported to the grid. Energetix believes its ORC based appliance will have a significantly shorter payback period compared than other microCHP technologies under development.

The unit is compact, wall-hung, light-weight, and tailored for installation in UK homes, says Energetix. It incorporates the company’s Genlec ORC microCHP technology, which generates electricity using heat produced by a gas boiler (see basic process diagram above). The target performance for the Kingston appliance is to have an overall efficiency equivalent to a high-efficiency condensing boiler and an electrical efficiency of 10%.

The Kingston is undergoing laboratory tests to determine its heating and electrical performance, and is expected to gain full UK certification, including CE compliance during 2010. Potential manufacturing and marketing partners have “shown significant interest in the appliance”, the company say.

Adrian Hutchings, CEO of Energetix Group, said his company “took the decision to develop and introduce a fully integrated appliance for UK homes, having recognised that the market conditions for microCHP were likely to improve. This has resulted in the unveiling...of the Kingston. We are currently in discussions with a major white goods appliance manufacturer and with power utilities for both its production and sale in the UK.”

“At Energetix we view the feed-in tariffs as useful in helping to drive the uptake of our microCHP products; however, unlike other microCHP technologies, our Genlec product is inherently low-cost in initial outlay and maintenance and, as such, the economic case for Kingston is not reliant on any such subsidies.”

Energetix’s strategy is to create products based on robust engineering principles, regularly utilising existing mass-produced components configured in a novel and patentable way. A good example of this is the scroll expander, which is at the heart of its ORC based microCHP offering, and also employed in another of its products, a compressed-air back-up power system. The scroll expander is based on the scroll compressor, which is mass produced and widely used in refrigeration and air conditioning. In the Energetix ORC concept (which originated with Battelle), the scroll compressor is basically run in reverse to become an expander.

Energetix says that avoiding cutting-edge science has enabled it to de-risk new product development processes, which in turn reduces development time and costs. This has enabled it to achieve a lower-than-normal technology risk while still producing strong intellectual property. In addition, this facilitates the outsourcing of production and assembly, significantly reducing the needed investment in capital equipment. The body of know-how developed within the company has also “enabled the businesses to modify the design of existing mass-produced components to reduce costs, improve efficiency and strengthen the...intellectual property position,” the company says.

Energetix Group plc now has three businesses with “cost-effective products”, it says, in the areas of distributed generation, energy storage and energy efficiency, the businesses being: Energetix Genlec Limited – ORC based distributed generation in the home, including the Kingston microCHP unit; Energetix (Pnu) Power Limited – compressed-air back-up power (based on the same scroll expander technology as the microCHP); and VPhase plc – domestic energy efficiency.

Energetix Group joined AIM in August 2006. The Group and its subsidiaries are all based near Chester, north west England.