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advertising verification


We make several claims in our advertising which we have verified using third-party studies and information from the power station in the following page
Ad clearing service
  • Power station peak times

    The best time to use electricity in Guernsey is between 23:00 and 05:00. During this period, demand is low and the power station is not required to top up our electricity demand. When demand exceeds the 60MW renewable importation capacity, Guernsey Electricity will start a diesel generator at the power station. When demand exceeds around 70MW, a second diesel generator is required to meet demand. 

    Read More
  • Electric Heating

    Heating powered using electricity in Guernsey produces over 70% less carbon than oil heating and over 60% less than LPG gas liquified petroleum gas. This takes into account the entire lifecycle of each heating type, and for electricity this includes electricity generated using diesel generators at the Vale power station. 


    Read the study
  • Electric vehicles

    In Guernsey, most electric vehicles will produce around 65% less carbon emissions than a petrol vehicle and around 55% less than a diesel vehicle. These figures are calculated across the vehicle's entire lifecycle, and for electric it includes production of the lithium-ion battery, top-up diesel generation at the Vale power station, and final disposal. 

    Read the study

Green Claims Code

We will do our utmost to ensure our marketing communications are in line with the Competition and Marketing Authority's Green Claims Code. If you believe any of our advertised material does not adhere to the key points listed on the Green Claims Code website, please let us know.  

Power Station Peak Demand

Power station peak times
Topping up our renewable importation

Renewable Electricity

Guernsey imports 60MW of 100% renewable electricity from the European grid. This is marked by the green line on the linked graph. 

Diesel Generation

When demand exceeds 60MW, the power station is required to start up a diesel generator to supply the island with the electricity required.

At times when demand is around 70MW or more, a second diesel generator is required which has been marked in orange on the linked graph. 

Peak time

Electricity usage follows human behaviour and means demand peaks at certain times.

8am, 2pm and 6pm are the most common peak times and during winter, this is when most demand is placed on the power station. 

During a typical summer, demand remains below 60MW and the power station is not required to top up our electricity demand. 

What is the GEL mix?

Electricity in Guernsey is made up of a mix of sources

Annually this consists of over 90% imported hydro, wind and solar power, with the rest topped up by on-island community solar power and diesel-generated electricity from the Vale power station. 


Electric Heating

Electric heating
Cleaner, greener heating that doesn't cost the earth.

The carbon intensity of heat sources available in Guernsey are shown in this table and graph as of 31 December 2021. 


1. Fuel - lifetime carbon intensity (g CO₂e per kWh)

2. Usage - lifetime carbon intensity (g CO₂e per kWh)

Efficiency of equipment
Gas (LPG) 258 286 90%
Heating oil 348 387 90%
HVO* 26 29 90%
Air source heat pump (using electricity) 82.27 27 300% (COP 3)
Electric boiler  82.27 82 100%

*Hydrotreated vegetable oil 

Why are there two figures?

1. The figures in column 1 represent the grams of carbon dioxide equivalent present in the fuel source before it is used in the home. 

2. These figures demonstrate the impact boiler efficiency has on the carbon intensity of each fuel type and for the purposes of comparison, this table assumes each heating system is new. 

  • Gas, oil boilers will always be less than 100% efficient and will reduce as the boiler ages. This means as efficiency decreases, the carbon intensity will increase as more fuel needs to be burnt to produce the same level of heat
  • Electric boilers are practically 100% efficient and remain so throughout the heating system's lifetime as the 'fuel' (electricity) arrives ready to use
  • Air source heat pumps are powered using electricity, however mechanism within the system convert cold outside air into heat which can achieve a 300% efficiency 

EL Mix: This consists of diesel-generated electricity at the Vale power station, on-island community solar power and imported renewable energy. 

Lifetime Intensity: These carbon calculations for heating take into account the whole energy production chain. This includes exploration, extraction, processing, storage, transport, transformation into secondary fuels, final use, and disposal. 

The Guernsey Electricity's mix for the emissions intensity of GEL's electricity in 2020/21 includes an assumption based on the proportion of electricity generated by each energy source (oil and renewable imports) in 2019/20.  


*References: GEL sought independent advice from UK Carbon Emissions Specialists, WSP, in identifying the IPCC figures used in this note. 

powered with renewables
Over 90% of Guernsey's electricity is imported renewable energy

From 1st January 2020, all imported electricity supplies have Guarantees of Origin (GoO) certificates proving they are from renewable sources.

During 2020, over 90% of the energy the island used was imported from renewable sources. 

These renewable sources include solar, wind and hydro power, imported to Guernsey from France using our subsea cable. 

GoO's are issues for a controlled quantity of electricity generation (1 GO per MWh) and are used as evidence for customers on the source of delivered electricity, as set out in the Directive 2018/2001 of the European Parliament. 



key stages of the study
The assessment methodology included the following key stages:

1. The carbon emissions from GEL’s electricity production facility were calculated for the reporting period of April 2019 – March 2020. This included the combustion of fuels for electricity generation and all plant  activities involving the combustion of fuel. These calculations were carried out by GEL in line with Department for Environment, Food and Rural Affair’s (DEFRA) Environmental Reporting Guidelines,[2] (the ‘Guidelines’) which were updated in March 2019.

2. The life cycle carbon intensity of the renewable electricity imported through its interconnector by GEL, was provided by the electricity generating company through guarantee of origin (GoO) certificates for the reporting period. The life cycle carbon intensity of the other renewable electricity sources (solar, onshore wind and offshore wind) were identified through a literature review.[3],[4]

3. The well-to-tank emissions for all fuel used by GEL at its production facility, were calculated using DEFRA’s 2019 conversion factors.[5]

4. The sum of the emissions values from steps 1-3 provided the total life cycle emissions value (CO₂e) of the electricity that GEL provided to its customers in 2019/20.

5. WSP then calculated the carbon intensity of the electricity that GEL supplied its customers during 2019/20, using the following formula:

Footnotes graph for intensity

6. The life cycle intensity of GEL’s electricity was then forecasted to 2050, using GEL’s predicted electricity generation capacity and Guernsey’s electricity demand.


What does CO₂e mean?

This is short for carbon dioxide equivalent. 
CO₂e is a way to describe the overall contribution to global warming when taking into account the carbon dioxide (CO₂) as well as other greenhouse gas emissions, such as methane and nitrous oxide.  


Electric Vehicles

Driving forward a cleaner future, today

The lifecycle greenhouse gas (GHG) emission intensities of average vehicles driven in Guernsey are as follows:

Vehicle type Grams of CO₂e per km
Petrol 271.98
Diesel 209.12
Electric 97.17


charged 11pm to 5am

Renewable Diesel (RD100) 66.91

Data as of 31 December 2021

A recent independent study found that electric vehicles in Guernsey may produce up to 64% less carbon emissions than petrol vehicles. When charged between 11pm and 5am, this difference could increase to 69%. 

The lifecycle assessment includes, but is not limited to, carbon emissions generated from extracting raw materials, producing the fuel, generating the electricity, running the vehicle, and disposal 

Vehicle Lifetime: 150,000 km was assumed as an average lifetime usage of a car, based on estimates from literature available for the study. 

*References: GEL sought independent advice from UK Carbon Emissions Specialists, WSP, in identifying the IPCC figures used in this note. 

Lifecycle emissions
Lifecycle emissions for average vehicles: a breakdown

Lifetime Intensity. 

These figures take into account each stage of the vehicle production chain, including: 

  • Production of lithium-ion batteries
  • Electricity generated at the Vale power station
  • Fuel extraction
  • Exhaust pipe emissions
  • End-of-life/disposal emissions


The study takes into account Guernsey's total electricity mix:

  • Imported renewable hydro, wind and solar power
  • On-island diesel-generated electricity from the power station
  • On-island community solar power 
end of life emissions
Battery recycling

As the battery reclaim process develops, and when there is a stable supply of used batteries to reclaim, it is likely that the End-of-Life (EOL) impact of electric vehicles will significantly decrease in the coming years and further reduce the full lifecycle impacts of electric vehicles.

EOL emissions were discerned from the review paper Review and Meta-Analysis of EVs: Embodied Emissions and Environmental Breakeven (Dillman et al 2020). The review highlights inconsistency in data regarding emissions from the end-of-life stage and battery replacement; it asserted that this was because of a lack of available data on recycling technologies and their success as EVs have only relatively recently entered the mass market and many are yet to reach end of life. The EV EOL emissions factor is the mean average of the meta-analysis of a range of EV lifecycle assessments, of which a few of these studies included recycling aspects.


What stages were used in the study


Emissions generated during the production of all 3 types of vehicle. This includes producing the lithium-ion battery, together with raw material extraction and processing.


This includes exhaust pipe emissions from the combustion of petrol/diesel, emissions produced from generating electricity*, vehicle maintenance and well-to-tank (WTT) emissions.

*this includes electricity generated at the Vale power station. Electricity in Guernsey is made up of over 90% imported renewable energy – a mix of solar, wind and hydro power – with the remaining demand topped up by electricity from the power station.


The carbons emissions generated from maintenance work to keep the vehicle in good working order. 


This is when the vehicle, its part and components become waste and needs to be dismantled and disposed of. 

This EOL figure is an average of several studies which also take into account battery recycling aspects.  

Well-to-tank (WTT)

WTT specifically refers to the journey of the fuel used in the vehicle, from extraction (well) to final use in the petrol or diesel vehicle (tank).

Our study used data taken from a scientific publication which reviewed and consolidated the results from many lifecycle emission assessments on different vehicle types. 

Advertising campaigns

  • Work it 9 to 5

    This is an advertising campaign run by our sub-brand Electric Living to encourage electricity customers to consider switching some of their electricity usage to between 9pm and 5am while the power station is still being used during early 2022. 

    Verification Letter

Frequently asked questions

We've answered some of the questions asked about electricity in Guernsey

Why aren’t we being more self-sufficient?

We need to have a secure supply and local renewables alone cannot provide the electricity we need today, let alone in the future. Using a mix of sources will offer reliability and security for a sustainable supply.
Importing electricity today is the bridge to tomorrow's technology and will enable more local renewables. A second cable also opens up the opportunity to sell electricity to Europe.

We have the largest tidal range in the world, why aren’t we focusing on tidal power?

This is becoming commercially viable, but at the moment it is not affordable for the island. The potential for exploiting Guernsey’s tidal range was investigated at Cobo Bay,  Havelet Bay, Victoria and Beaucette marinas but the outputs and generation were initially too small to justify further investigation. 

Will we still need the power station in the future?

The import cable alone does not meet the islands electricity needs when energy demand is at its greatest. The GJ1 cable can provide 100% of Guernsey’s energy needs in summer and around 75% in winter, so the power station is still required as both a top-up for the winter peak periods and as a back-up when the GJ1 interconnector requires to be switched off for maintenance.

Guernsey Electricity’s long-term strategy is for an energy system that supports renewables and reduces the reliance on fossil fuels to use the power station for emergency generation only.

This second cable would mean that the power station will no longer need to ‘top-up’ supplies and will act purely as a ‘back-up’ for emergencies.