Dr Gregor Czisch from the University of Kassel in Germany claims that a 100% renewable power supply for Europe is possible. In a series of papers and reports he suggests that a programme of renewable energy - largely wind power supported by biomass and existing hydro power for storage and smoothing - can meet the EU's entire future electrical energy needs at cost levels similar to those at present, with the same level of reliability, and without the need for nuclear or fossil fuel.

The key to his approach is the use of high-efficiency High Voltage Direct Current (HVDC) transmission grids, which make it possible to use wind-derived power not just from the EU but also from remote but windier regions around the EU including Kazakhstan, which he says has a wind potential of 210GW and Northern Russia and Western Siberia (350GW). He also looks at the wind potential in Mauritania (105GW) and Southern Morrocco, which he puts at 120GW.

Solar power might also play a role. He notes that, in addition to 120GW in Germany, 10GW in Portugal and 5GW even in Finland, the PV potential for Algeria and Morocco is 81GW, and 32GW for Mauritania & Senegal. However, his analysis discounts PV as too expensive compared to wind, while Concentrated Solar Thermal power (CSP) is also seen as expensive at present, but it is expected to come down in price.

In his base case supergrid scenario, nearly 70% of the power originates from wind energy produced from wind turbines with a total rated power of 1040GW. He say that in the case of a high percentage of electricity being produced from wind power, with a wide cross-continental footprint including N Africa, Kazakhstan and Russia, "the instances of excessive generation will be significantly reduced as well as the periods of relatively low feed-in from wind power". But in addition "biomass and existing hydroelectric power plants provide most of the backup requirements within the supply area, in which the individual regions are strongly interconnected via HVDC transmission lines". A smaller contribution comes from CSP, but, "if the costs of the mirror fields of solar thermal power plants were reduced by half – as is anticipated in the near future – solar thermal power plants would ... constitute about 13% of all electricity generation".

On the basis of his estimates he claims that the supergrid could deliver wholesale electricity at a cost of EUR0.047/kWh, compared with EUR0.06 - 0.07p/kWh for electricity from gas-fired plants.

This proposal is, of course, only one of several. On a somewhat smaller scale, but still very ambitious, Airtricity, working with ABB, has proposed a supergrid running from Spain to the Baltic Sea, linking up countries around the North Sea and beyond, with a network of offshore windfarms at nodal points in the North Sea and off the west coast of the UK and Ireland. "The primary benefit of the supergrid is that it aggregates wind power across geographically dispersed areas, and, by doing so, it smoothes the output of those wind farms," says Airtricity director Chris Veal. The initial proposal is for a GBP20bn, 10GW wind farm project in the southern part of the North Sea, with a 5GW HVDC link carrying power west to the UK, and a second 5GW line running east to continental Europe, perhaps to the Netherlands. This could be seen as the first stage in the Czisch cross continental mega scheme.

Other mega proposals include the supergrid scheme being promoted by DESERTEC, which includes the use of focused solar Concentrated Solar Power (CSP) units in N Africa - as reported earlier in Clean Energy Insight. The full version of this includes links across Europe, North Africa and the Middle East, tying in wind, biomass, hydro and geothermal generation as well as CSP.

Mega schemes like this do of course raise many issues, for example about the security aspects of the super grid and the problems of negotiating grid link access across the whole continent - especially in N Africa and Russia. There is also the danger that governments might buy into this approach rather than sorting out energy problems at home - it could be used as an excuse for inaction. For example, what about the merits of decentral power? After all, it makes sense to use local sources where possible to meet local needs, with any excess being exported and any shortfalls being imported via the grid. Also, the supergrid approach is just about electricity. But we may decide to build in more local storage, as heat, or go to hydrogen as a buffer store - blurring the distinction between electricity and heat vectors. Optimising for electricity on a least-cost basis may not be optimising for energy as a whole. So the supergrid proposal may only be part of a wider programme. Even so, it could be part of a significant new direction for development.

Interestingly, a meeting of more than 100 leading European engineers, representing 21 European countries, brought together under the auspices of the Royal Academy of Engineering (RAEng) in London to discuss Europe's renewables challenges, saw a majority supporting the construction of a pan-European energy supergrid: 86% of the engineers thought it a good way to balance out the intermittency of renewable power sources across the continent.

Likewise, the Claverton Energy Group, an informal network of around 200 UK energy practitioners, was generally very impressed when Dr Czisch made a presentation of his ideas at the group's fourth conference in October 2008. Dave Andrews, Claverton Energy Group secretary and conference organiser said: "Dr Czisch's European super grid is a clearly defined long-term solution for our energy needs that does not include nuclear power or the building of more coal- and gas-fired power stations. This largely confounds the claims of various energy experts who claim renewables cannot meet UK power needs, who make this assertion without reference or criticisms of Czisch's detailed analysis."

Czisch’s full report is "Low Cost but Totally Renewable Electricity Supply for a Huge Supply Area - a European/Trans-European Example".