UK microgeneration. Part II: technology overviews.

This paper reviews the current status of microgeneration technologies at the domestic scale. Overviews are given for nine such technologies, grouped into three sections: (a) low carbon heating: condensing boilers, biomass boilers and room heaters, air source and ground source heat pumps; (b) renewables: solar photovoltaic panels, flat plate and evacuated tube solar thermal panels and micro-wind; and (c) combined heat and power: Stirling engines, internal combustion engines and fuel cells. Reviews of the construction, operation and performance are given for the leading commercial products of each technology. Wherever possible, data are presented from the field, giving the actual prices paid by customers, efficiencies and energy yields experienced in real-world use, reliability and durability, and the problems faced by users. This information has a UK focus but is generally relevant in the international context. Two issues are found to be prevalent throughout the microgeneration industry. Total installed costs are a premium and vary substantially between technologies, between specific products (e.g. different models of solar panel), and between individual installations. Performance in the field is found in many cases to differ widely from manufacturers quotes and laboratory studies, often owing to installation and operational problems. Despite this, microgeneration has demonstrated substantial improvements over conventional generation in terms of fossil fuel consumption, carbon dioxide emissions and energy cost, provided that the appropriate technologies are employed, being installed and operated correctly according to the load requirements of the house and their physical location.