As well as the more familiar Renewables Obligation Certificate and the Feed-in Tariff, the more recent Renewable Heat Incentive (RHI) makes biomass and ground source heat pump systems particularly appealing right now, he explained.
"RHI is guaranteed for 20 years and is index-linked. Biomass is worth a look at, especially if you are currently on oil - you could pay it back in under four years," he said. Working out the correct boiler size is complex, though, and securing a regular supply of fuel of known quality is crucial, he advised.
Pratt said anaerobic digestion is also benefiting from RHI support, but this is a more specialist technology with high start-up costs. Wind, meanwhile, "is a relatively secure, low-maintenance investment", he said. "The big question is, how windy is your site? Consult the UK wind map to make sure you have speed of at least 6m/s on average. Planning permission is also an issue."
The cost of photovoltaic (solar) "has gone through the floor, but still isn't the best in terms of return on investment", he added.
While geothermal energy projects are being pursued by Dutch growers, Pratt said: "It's like drilling for oil - you don't know it's there until you find it." He added: "Energy efficiency is still the best investment you can make."