Consumer publication Which? has rated 33 suppliers of energy to UK homes.
Around seven in 10 customers think companies that sell them green energy should be buying it straight from generators, but this is not always borne out by the reality, according to research from Which?
The consumer publication said that only a handful of the 33 energy suppliers it surveyed produced a large proportion of their own renewable electricity, or bought it from the producer.
Many have instead relied on so-called Renewable Energy Guarantees of Origin (Rego) certificates, which their critics dismiss as cheap pieces of paper which allow companies to claim their energy is green.
In a newly released rating of firms’ green credentials, three smaller suppliers came out on top – Good Energy, Ecotricity and GEUK.
They were the only suppliers that were granted an “Eco Provider” badge by the group.
Their approach to renewable gas and electricity largely matches what green-conscious customers expect, Which? said.
Good Energy, which scored 19 out of 20 points in the study, buys most of its renewable electricity from the generators, and even produces some of its own.
However other suppliers argue that putting up their own wind turbines or solar panels is unrealistically expensive.
Utilita, which scored one out of 20, told Which? that its efforts were aimed at helping households reduce their energy usage.
Scottish Power is one of the biggest green energy generators in the country, so can tap into its own wind farms to get electricity to customers.
Which? Magazine editor Harry Rose said: “We know consumers are growing ever more environmentally conscious, and our research shows that some energy firms go to great lengths to invest in the technology we need to clean up the grid, generate renewable electricity, or buy it from renewable generators.
“However, some other energy suppliers do the minimum required to label their tariffs ‘green’ and it can be hard for consumers to understand what they are buying.
“Which? believes there needs to be greater clarity on how renewable electricity is defined and marketed. People can only make informed decisions about where to buy their energy from if firms are more upfront and transparent about their green credentials.”
The greenest energy suppliers (score out of 20)Good Energy – 19GEUK – 16Ecotricity – 14British Gas Evolve – 12Scottish Power – 11.5British Gas – 11Bulb – 11Co-op Energy – 11London Power – 11Octopus Energy – 11E.on – 10E.on Next – 10Sainsbury’s Energy – 10Shell Energy – 10Ovo Energy – 9So Energy – 9Affect Energy – 9Ebico Living – 9M&S Energy – 9Qwest Energy – 9Roar Power – 9Omni Energy – 7Orbit Energy – 6Outfox the Market – 6Goto Energy (defunct) – 5Together Energy – 5Neon Reef – 4SSE – 4ESB Energy – 3Boost – 2Utility Warehouse – 1.5Northumbria Energy -1Utilita – 1