Green energy tariffs, which divert a share of money from customers' energy bills to funding grants for renewable energy sources, make up a tiny share of the market.
In a survey conducted for the independent consumer watchdog Energywatch last month, only 1 per cent of consumers said they used such a scheme.
Some of the tariffs are funding grants to organisations that want to use or generate renewable energy in some way. Scottish Power's Green Energy Trust, funded through the company's 'green fund option', has been running for 10 years, and has made £1m available in grants in that time.
The trust will grant up to £25,000 to projects "that advance renewable energy and that support communities through education and public engagement". It has supported technologies including small-scale hydro-electricity, wind power, biomass, landfill gas and ground-source heat pumps.
Some of the technologies - especially wind power and biomass - are controversial. Although Scottish Power has a good environmental record, it has been publicly criticised for its support for wind energy and biofuels. Alison McKean, head of environment for ScottishPower Energy Retail, says that these debates don't affect the trust's grants policy. "It might be that a certain technology raises questions, but we're more concerned about whether the right technology has been used for a certain context.
"We are looking at the benefits to the wider community. For instance, we'd look favourably on an application for solar panels or a wind turbine for a community hall. Recently we've supported one that was for air-sourced heat pumps that were being used to heat the water in one of the last remaining swimming pools in New Cumnock in Ayrshire."
The subscribers to Scottish Power's green tariff are, so far, a loyal group - the trust doesn't expect them to switch allegiances to cut their fuel bills. But given the increasing financial pressure on consumers to save money, it may be worth sector bodies putting in applications now while the funding is still available.