100Green Energy Review: The UK's Only 100% Green Gas and Electricity Supplier
In the journey towards a net-zero future, UK consumers are increasingly seeking energy suppliers that align with their environmental values. While many providers offer "green" tariffs, 100Green (previously known as Green Energy UK) has carved out a unique position in the market. They are currently the only UK supplier guaranteeing both 100% renewable electricity and 100% green gas.
This comprehensive guide explores what makes 100Green different, from its energy sources and tariffs to its customer service and pricing structure, helping you decide if it's the right choice for your home.
1. Who Are 100Green?
100Green was founded in 2001 by Doug Stewart and remains an independent UK energy supplier, based in Ware, Hertfordshire. The company has built its reputation on a straightforward promise: genuinely green energy without the offsetting schemes used by many larger suppliers. Perhaps less well known is its ownership structure—100Green is the first and only private UK company to offer free shares to its customers, who can then make recommendations to help improve and grow the business. All customer shareholders are free to attend 100Green's AGM and question board members, giving households a genuine say in how the company is run.
2. What Truly Sets 100Green Apart?
In a marketplace where "green" can sometimes be a confusing label, 100Green's proposition is refreshingly straightforward. Their core commitment is to provide energy that is as sustainable as currently possible, a promise that extends beyond just electricity.
100% Green Gas: A UK First
The most significant differentiator for 100Green is its gas supply. While other suppliers may offer carbon-offset gas tariffs, 100Green directly supplies biomethane, or 'green gas'. This isn't a fossil fuel with its emissions balanced elsewhere; it's a completely different product. As independent comparison sites confirm, only one supplier currently offers 100% fully renewable gas – 100Green, whereas most other suppliers that offer green gas promise to cover just 10% of usage, with some offering anything from 6% to 25%.
The gas is produced through a process called anaerobic digestion. This involves breaking down organic matter—such as agricultural waste, food waste, and crops grown specifically for energy—in an oxygen-free environment. This process releases biogas, which is then purified to become biomethane and fed directly into the national gas grid. 100Green describes the distinction simply: the gas is created from the natural decay of organic waste, not fossil fuels formed millions of years ago, with the renewable gas captured from the decomposition of organic waste rather than extracted from the earth's crust. By choosing 100Green, customers ensure that for every unit of gas they use, an equivalent unit of green gas has been produced and supplied to the network.
It's worth noting that 100Green itself acknowledges this is part of a broader transition rather than a permanent end state—green gas is seen as a short-term solution as the UK attempts to move away from gas entirely, though it remains an innovative move that no other supplier currently offers.
100% Renewable Electricity
Alongside its unique gas offering, 100Green supplies 100% renewable electricity. This energy is generated exclusively from UK-based natural sources, including:
- Wind Power: Harnessing the power of the UK's ample wind resources.
- Solar Power: Capturing energy from the sun via photovoltaic panels.
- Hydropower: Utilising the flow of water to generate power.
- Organic Generation: Creating energy from biomass and other organic materials.
Crucially, 100Green's fuel mix does not include nuclear power. While low-carbon, nuclear energy is not considered renewable due to its reliance on finite resources like uranium and the long-term environmental challenges of waste storage. 100Green emphasises the provenance of its supply too, noting that it sources renewable energy from a trusted portfolio of independent generators across the UK, and prides itself on real relationships with the local generators it partners with.
3. Understanding 100Green's Tariff Options
To cater to different customer needs, 100Green provides a range of straightforward tariffs. A standout feature across all their plans is the absence of exit fees, giving customers complete flexibility to switch away if their circumstances change without financial penalty. As the supplier puts it on its own site, "we don't want to penalise you if you decide we're not quite what you're looking for. So there are no exit fees either. Simple as that."
- Fixed Tariffs: For those who value price certainty, fixed tariffs lock in your unit rates and standing charges for the duration of the contract, protecting you from market volatility. 100Green also offers a 'premium' green tariff—currently branded EKO—which fulfils strict sustainability criteria, including local wildlife protection where energy is generated, and also helps finance renewable energy projects in developing countries. According to 100Green, the EKO tariff has been additionally verified as super-green by an independent, not-for-profit organisation, giving an extra layer of reassurance beyond the standard green guarantee.
- Standard Variable Tariff (SVT): Branded Sparkling SVT, this tariff has no fixed end date, and tracks the wholesale market, meaning your prices can go up or down. The supplier is obligated to provide 30 days' notice of any price changes.
- Time-of-Use Tariffs: Specifically designed for households with high overnight energy consumption, such as electric vehicle (EV) owners. 100Green now offers three time-of-use tariffs, designed so that the more you can shift your usage, the lower your rates become. These typically require a smart meter and offer a significantly cheaper rate for electricity during an off-peak window, making it much more economical to charge an EV or run appliances like washing machines and dishwashers overnight. For those with compatible meters, an Economy 7 option is also available, offering cheaper electricity during a seven-hour night-time window.
4. The Price Cap Exemption: What Does It Mean?
You may notice that 100Green is exempt from the Ofgem energy price cap. This special status is granted to a small number of suppliers who can demonstrate that their business model genuinely supports and invests in renewable energy generation.
The exemption means their Standard Variable Tariff can be priced higher than the cap set by the regulator. However, this is a reflection of the real-world cost of producing 100% green gas and electricity without relying on carbon offsetting. Independent reviewers note that this premium is real and measurable: tariffs are typically 8–15% higher than standard suppliers, with green electricity averaging around 32p/kWh, and the price gap between green energy and standard tariffs tends to widen the more energy you use. Customers on this tariff have made an active choice to opt in, prioritising the highest level of environmental sustainability over the lowest possible price.
5. Customer Service and User Experience
100Green has built a reputation for strong customer service, a fact underscored by its win as Best Small Supplier in the 2025 Uswitch Energy Awards, where it was also commended for Outstanding Green Contribution. The company has also achieved Which? Recommended Provider status for both 2025 and 2026, putting it among just four suppliers in the UK to earn that distinction, and ranking among the top three in the Citizens Advice customer service charts.
Unusually in an age of chatbots and online-only support, the company actively encourages customers to get in touch via telephone for a more personal service. 100Green is explicit about this point of difference, stating that it doesn't use automated menus or chatbots, and that calling the company always connects you to a real person who genuinely wants to help.
To support modern account management, 100Green also offers:
- A Mobile App: Available for both iOS and Android, the app allows customers to manage their accounts, submit meter readings, and view their energy usage.
- Smart Meters: They provide and install smart meters for free, which is a prerequisite for their time-of-use and Economy 7 tariffs.
Customer feedback on independent review platforms remains strong. On Trustpilot, recent reviewers describe the company as very easy to make contact with, with no waiting or multiple stages to go through, and praise professional agents who understand and answer queries quickly. The company has accumulated nearly 1,500 reviews on Trustpilot, with feedback generally praising both green credentials and the helpful, UK-based support team. Some customers have even reported proactive outreach from the supplier—one reviewer noted receiving an unprompted call from a member of staff offering to move them onto a cheaper tariff and help with arrears, something they said they'd never experienced with a previous provider.
6. Additional Products and Services
Beyond supplying energy, 100Green is engaged in creating a more flexible and sustainable energy system.
- High Tide Scheme: This is their version of the Demand Flexibility Scheme. Customers are rewarded with account credit for reducing their electricity consumption during specified peak hours, helping to balance the grid and reduce reliance on fossil fuel power stations.
- Energy Export: For homeowners with solar panels, 100Green will purchase any surplus electricity you generate and export to the grid, providing you with credit on your account.
- Business Energy: 100Green doesn't only serve households. The company also provides commercial energy contracts, and according to industry reviewers, 100Green gives businesses genuinely sustainable energy solutions while maintaining competitive pricing and award-winning support, with their environmental commitment going well beyond standard renewable electricity offerings. Some business customers choose 100Green specifically because larger clients and government contracts increasingly require proof of environmental responsibility from their suppliers, making the green premium a worthwhile cost of entry for certain sectors.
7. Is 100Green the Right Supplier for You?
Choosing an energy supplier is a personal decision based on budget, priorities, and values. 100Green is an excellent fit for:
- The Environmentally Conscious Consumer: If your primary goal is to minimise your household's carbon footprint with the greenest fuel available, 100Green is arguably the best choice in the UK. As one independent reviewer puts it, if you want the greenest possible energy and are willing to pay for it, 100Green is the clear market leader.
- Electric Vehicle Owners: The time-of-use and Economy 7 tariffs offer substantial savings for those who can shift their charging to off-peak hours.
- Customers Seeking Transparency: Their straightforward promise of 100% green gas and electricity, without complex offsetting schemes, offers clarity.
- Those Prioritising Service: If you're tired of long call queues, automated menus, and poor support, 100Green's UK-based, award-winning team is a significant draw.
- Customers Wanting Flexibility: With no exit fees on any tariff, you're free to leave at any time without penalty—useful if your circumstances or priorities change.
However, it may be less suitable for those whose primary concern is finding the absolute cheapest tariff on the market, as their price cap exemption reflects the premium cost of their genuinely green energy. For high-usage households, this premium can add up significantly, so it's worth weighing the environmental benefits against the likely cost difference for your specific usage profile.
8. How to Switch to 100Green
Switching is a simple process. Using an energy comparison website, you can enter your postcode and usage details to see if 100Green is available in your area and how its prices compare to other deals. Alternatively, 100Green's own site allows you to get a quote via their tariff calculator by entering your postcode, your energy usage, and whether you want electricity only or electricity with green gas as well. The switch itself is handled entirely by the suppliers and typically takes just a few weeks with no interruption to your power supply.
9. The Bottom Line
For UK households and businesses that put genuine environmental impact at the top of their priority list, 100Green remains in a category of its own. Its position as the only supplier offering true 100% green gas—not just offset gas—combined with consistently strong customer service ratings and a customer-ownership model that's almost unheard of in the energy sector, makes it a standout option. The trade-off is cost: as a price-cap-exempt supplier, 100Green's tariffs sit above the market average, and that premium grows with usage. For most households, the decision ultimately comes down to how much value you place on knowing your gas and electricity are genuinely, verifiably green—rather than green on paper through offsetting schemes alone.
