Experts have warned that environmentally-friendly tariffs offered by energy suppliers are not always as good for the environment as they claim.

In fact, many tariffs advertised as being 100% renewable are actually using fossil fuels and then simply offsetting the carbon impact for a small price.

Regen, the sustainable power think tank, looked at how 'loose marketing and looser language' were being used to mislead the public over what actually constituted a 'green tariff'.

However, Energy UK, the industry body, has argued that any kind of renewable tariff has a role to play in transforming the UK's energy grid to create a low-carbon economy.

Most energy suppliers are now advertising their green tariffs, with many also promising the standard of '100% renewables'. However, some are being accused of using advertising spin to 'greenwash' dirty electricity and to make it seem clean.

Green tariff sales have increased rapidly since 2015 and doubled from 2017 to 2018, according to the Energy Research Centre.

Many UK consumers are also now actively seeking out green tariffs. However, those that believe they are buying clean energy from sources such as hydro, wind and solar may be shocked to find that their supplier is actually buying electricity from fossil fuel sources on the wholesale market and then buying cheap REGOs - renewable energy certificates - that act as offsetting tools which legally allow them to market the end result as100% renewable.

The government has confirmed that it will be reviewing the scheme for REGOs this year so that consumers can make better-informed decisions over how they make sustainable purchasing decisions.

An adjustment to the scheme could also impact the way that energy suppliers market their tariffs and force clarity over the true origin of their so-called 'green' tariffs.