What green energy tariffs actually mean, how they work, whether they're truly renewable, and how to choose a genuinely green energy supplier.
·3 min read
Green energy tariffs claim to supply your home with renewable electricity (and sometimes gas). But the reality is more nuanced. Here is what green tariffs actually mean and how to choose a genuinely sustainable option.
How Green Tariffs Work
Concept
Reality
Physical electricity
All goes into one National Grid — you can’t choose which electrons reach your home
What suppliers do
Match your usage with renewable energy certificates (REGOs)
REGO
Renewable Energy Guarantee of Origin — certificate proving 1MWh of renewable generation
The impact
Suppliers buy from or invest in renewable generation
Types of Green Tariff
Type
What It Means
Genuineness
REGO-backed
Supplier buys certificates to match your usage
Basic green claim
Direct PPA
Supplier has Power Purchase Agreements with specific renewable generators
More genuine
Own generation
Supplier owns wind/solar farms
Most genuine
Green gas
Includes biomethane or renewable gas
Look for actual green gas, not just offsets
Carbon offset
Offsets emissions rather than true renewables
Least genuine (greenwashing risk)
Evaluating Genuineness
Questions to Ask
Question
Good Answer
Red Flag
Where does the energy come from?
Named wind/solar farms, direct PPAs
“Various renewable sources”
Do you own any generation?
Yes
Just buy REGOs
What % is backed by PPAs?
High (50%+)
0% — just certificates
Is gas green?
Biomethane or green hydrogen
“Carbon offset” only
Investment in new renewables?
Yes, X MW being built
No investment
Rating Scales
Rating Source
Top Rated Suppliers
What They Measure
Which? Eco Providers
Good Energy, Ecotricity, Octopus
Transparency, investment, fuel mix
Uswitch Green Accreditation
Various
Minimum green standards
Your own research
Check supplier’s fuel mix disclosure
Annual reports, websites
Best Green Energy Suppliers
Supplier
Own Generation
Green Gas
Rating
Good Energy
Yes (solar, wind)
Biomethane
Top
Ecotricity
Yes (significant wind)
“Green gas”
Top
Octopus Energy
Growing generation + PPAs
Carbon offsets (some criticism)
Good
Bulb (now Octopus)
PPAs, investment
Carbon offsets
Good
EDF
Nuclear (low carbon, not renewable)
Some offsets
Mixed
Ovo
PPAs, tree planting
Offsets
Mixed
Big Six on green tariffs
Mostly REGO-backed
Offsets
Basic
Cost Comparison
Tariff Type
Cost vs Price Cap
Best green tariffs
Often at or below cap
Premium green (small suppliers)
Sometimes 5–15% above cap
Big supplier green tariffs
Usually at cap level
Standard (non-green)
At cap (SVT)
Key point: Being green does not have to cost more. Compare prices — the best green deals compete with any tariff.
Green Gas: The Challenge
Issue
Detail
Gas is harder to green
Most UK heating is gas-based
Biomethane
Genuine green gas from organic waste — limited supply
Green tariffs are one part of the puzzle. Combined with efficiency measures, they help — but the grid is decarbonising regardless as the UK builds more renewable capacity.