What does "100% renewable electricity" mean?
When a supplier markets a tariff as "100% renewable", it generally means the supplier has matched the electricity you use with renewable generation through Renewable Energy Guarantees of Origin (REGO) certificates. For every unit of electricity a renewable generator produces; from wind, solar, hydro, or biomass; a REGO certificate is issued. Suppliers buy and retire these certificates to back the electricity they sell on green tariffs.
Because the UK's electricity all flows through the same national grid, it's not possible to physically direct specific electrons from a wind farm to your home. The REGO system is the mechanism that allows suppliers to make verifiable claims about the renewable origin of the electricity they supply, matched against actual generation.
Why this matters for comparing tariffs
REGO certification means a green tariff claim is backed by a real, auditable record; but it doesn't necessarily mean the supplier itself is investing in new renewable generation, or that your switch directly causes more renewable energy to be built. Some suppliers go further, investing directly in renewable generation projects or offering tariffs linked to specific wind or solar farms. If this distinction matters to you, it's worth checking what a supplier says about its own generation mix and investments, not just the headline "100% renewable" claim.
Gas and green tariffs
Green tariffs typically refer to the electricity portion of a dual-fuel deal. Gas supplied through the grid is overwhelmingly natural gas, and genuinely "green gas" (such as biomethane) makes up a small fraction of the network. Some suppliers offer carbon offsetting on the gas portion of a tariff, where the supplier funds projects intended to offset the carbon emissions associated with your gas use. Offsetting is a different mechanism from REGO-backed renewable electricity, and it's worth understanding which (if either) applies to a tariff you're considering.
Are green tariffs more expensive?
Not necessarily. Renewable generation costs have fallen significantly over the past decade, and many green tariffs are priced competitively with standard tariffs; sometimes identically, sometimes cheaper, depending on the supplier and current market conditions. The only way to know for a specific postcode and usage level is to compare, the same as for any other tariff.
What to check before switching to a green tariff
When comparing tariffs marketed as green or renewable, a few things are worth checking on the comparison result or the supplier's own information:
- Whether the claim covers electricity only, or electricity and gas; and if gas is included, whether that's through offsetting or genuinely green gas
- Whether the tariff is fixed or variable, since this affects price stability independently of how green it is
- The unit rates and standing charges, compared against other tariffs for your postcode and usage
- Any additional information the supplier provides about its renewable generation or investments, if that's important to you beyond the REGO certification baseline