Scientists are working to develop a reactor that produces fuel using sunlight and carbon dioxide in a bid to cut carbon emissions.

The international research team, led by Heriot-Watt University in Edinburgh, will try to increase the efficiency of photocatalytic reduction, a process that uses solar energy to convert carbon dioxide (CO2) into fuels such as methane and methanol.

Carbon produced when the clean fuel is used is converted back into energy by a closed-loop system, researchers said.

The team has been given a £1.2 million grant by the Engineering and Physical Sciences Research Council, in an attempt to increase the photo-catalytic process for wider use.

If successful on a commercial scale, the scientists estimate the process could offset 700 million tonnes of CO2 each year.

Existing photocatalytic reduction processes do not produce enough fuel to make them financially viable, according to the university. The project will involve developing new, photo-reactors, with conversion rates that can be scaled up to a commercial process.

Professor Mercedes Maroto-Valer, director of the Centre for Innovation in Carbon Capture and Storage, will lead the work in the UK.

She said: "We are working on creating a technology that will turn a climate-changing gas into a climate-saving fuel."