Vast farms of solar panels in the Sahara desert could provide clean electricity for the whole of Europe, according to EU scientists working on a plan to pool the region's renewable energy.

Harnessing the power of the desert sun is at the centre of ambitious scheme to build a €45bn (£35.7bn) European supergrid that would allow countries across the continent to share electricity from abundant green sources such as wind energy in the UK and Denmark and geothermal energy from Iceland and Italy.

The idea is gaining growing political support in Europe with both Gordon Brown and Nicholas Sarkozy recently giving backing to the north African solar plan.

Speaking today at the Euroscience Open Forum in Barcelona, Arnulf Jaeger-Walden of the European commission's Institute for Energy, said it would require the capture of just 0.3% of the light falling on the Sahara and Middle Eastern deserts to provide all of Europe's energy needs.

In addition, because the sunlight in this area is more intense, solar photovoltaic (PV) panels in northern Africa could generate up to three times the electricity compared with similar panels in northern Europe.

Jaeger-Walden explained how electricity produced in solar farms in Africa, each containing power plants generating around 50-200MW of power, could be fed thousands of miles across European countries by using high-voltage direct current transmission lines instead of the traditional alternating current lines. Energy losses on DC lines are far lower than AC ones where transmission of energy over long distances is uneconomic.

"If you look at solar radiation, then the Mediterranean region is a very favourable one," said Jaeger-Walden.

He said that the proposed grid was a way to balance out the intermittencies of renewable energy: "If you can connect the grid to hydro power, you've got that as a backup battery, and in addition there's wind. It's not a single source that's providing the energy but a combination of the different renewable energies."

Conveniently the potential to generate solar energy, either from photovoltaic cells, or by using it to heat water, is at its highest exactly when there is peak demand. "Between 11am and 1pm – there are a lot of cooking activities going on, people are going home, air conditioners are used," he said.

The idea of developing solar farms in the Mediterranean region and north Africa was given a boost recently by French president Nicholas Sarkozy earlier this month when he highlighted solar farms in north Africa as a key part of the work of his newly-formed Mediterranean Union.

Depending on the size of the grid, building the necessary high voltage lines across Europe could cost up to €1bn a year every year till 2050 but Jaeger-Walden pointed out that the figure was small when compared to a recent prediction by the International Energy Agency that the world needs to invest more than $45tr (£22.5tr) in energy systems over the next 30 years.

Much of the cost would come in developing the public grid networks of connecting countries in the southern Mediterranean, which do not currently have the spare capacity to carry the electricity that the north African solar farms could generate.

"Even if high voltage cables between North Africa and Italy would be built or the existing cable between Morocco and Spain would be used, the infrastructure of the transfer countries such as Italy, Spain, Greece and Turkey also needs a major restructuring," said Jaeger-Walden.

Scientists working on the project admit that it would take many years and huge investment to generate enough solar energy from north Africa to power Europe but envisage that by 2050 it could produce 100 GW, more than the the combined electricity output from all sources in the UK, with an investment of around €450bn.

Doug Parr, Greenpeace UK's chief scientist, welcomed the proposals. "Assuming it's cost-effective, a large scale renewable energy grid is just the kind of innovation we need if we're going to beat climate change. Europe needs to become a zero-carbon society as soon as possible, and that will only happen with bold new ideas like this one. Tinkering with 20th-century technologies like coal and nuclear simply isn't going to get us there."

Jaeger-Walden also believes that scaling up solar PV by having large solar farms could help bring its cost down for consumers. "The biggest PV system at the moment is installed in Leipzig and the price of the installation is €3.25 per watt. If we could realise that in the Mediterranean, for example in southern Italy, this would correspond to electricity prices in the range of 15 cents per KWh, something below what the average consumer is paying."

The vision for the renewable energy grid comes as the European Commission's Joint Research Centre (JRC) published its strategic energy technology plan, highlighting solar PV as one of eight technologies that need to be championed for the short to medium term future.

"It recognises something extraordinary – if we don't put together resources and findings across Europe and we let go the several sectors of energy, we will never reach these targets. We need a coordination of research applied to different fields," said Giovanni de Santi, director of the JRC, also speaking in Barcelona.

The JRC plan includes fuel cells and hydrogen, clean coal, second-generation biofuels, nuclear fusion, wind, nuclear fission and smart grids. De Santi said it was designed to help Europe to meet its commitments to reduce overall energy consumption by 20% by 2020 while reducing CO2 emissions by 20% in the same time and increasing to 20% the proportion of energy generated from renewable sources.

High-voltage transmission lines

First developed in the 1930s, High Voltage Direct Current (HVDC) transmission lines are seen as the most efficient way to move electricity over long without incurring the losses experienced in normal AC power lines. HVDC cables can carry more power for the same thickness of cable compared with AC lines but are only suited to long-distance transmission because they require expensive devices called static inverters to convert the electricity, usually generated as AC, into DC. Modern HVDC cables can keep energy losses down to around 3% per 1,000km.

Another advantage of HVDC is that it can be used as a link to transfer electricity between different countries that might use AC systems at differing frequencies. Alternatively, the HVDC cables could be used to synchronise the AC currents produced by renewable energy sources such as wind turbine farms.