Linking national grids to form a European supergrid to promote the effective use of sustainable energy would meet our electricity needs and environmental targets at a stroke. Ed Owen takes a closer look at the proposition.
The latest thinking on a European supergrid comes from Desertec, a consortium of Munich Re, Siemens, RWE, Eon, Deutsche Bank and more than a dozen other German companies, which in June began looking at finance to generate and distribute energy from North Africa. This energy would come from concentrated solar power (CSP), with project costs estimated at €400bn (£343bn).
Fundamental to the Desertec project is the supergrid. The idea is simple: generate renewable power wherever it is possible, then pump this around Europe via a super-efficient high voltage direct current (HVDC) grid to any number of countries, reducing or removing their need to burn fossil fuels.
Sound principles
While the Desertec idea is somewhat controversial − the few large-scale CSP plants in operation have proved very expensive − the principles behind it are sound, according to the world’s leading proponent of the supergrid, University of Kassel energy systems modelling specialist Gregor Czisch.
Czisch has developed an economic case for a renewable energy network extending from Siberia to Senegal using only renewable sources of power. These sources would be tied together using an HVDC grid.
From his research he has established a system that would be CO2-free: “I believe we would need 15% hydropower (there are huge reserves in Scandinavia), 17% to 18% biomass, two-thirds wind power and 1.6% solar thermal power,” he says.
Scale is the reason why the idea works. If the wind blows strongly on the Atlantic coast of the UK in the winter, for example, a great deal of power from thousands of wind turbines could be generated. But during a less windy summer those turbines would be relatively unproductive.
If the network is extended to the Sahara, where wind reserves exist during the summer, the load can be balanced over a year and a constant supply maintained. At peak times, energy can be released quickly from vast hydro reserves in Scandinavia.
In extreme cases, the system can be backed up with traditional fossil fuel power stations, which can be fired-up using stockpiled quantities of coal or gas. These stations would be used infrequently and emit a fraction of the CO2 of existing plants.
Unsolved problems
Proponents of developing a 100% renewable energy source believe it is incompatible with building new nuclear power stations (NCE 25 June), as nuclear power plants cannot be easily turned on and off to match the load availability of other sources.
According to the Claverton Group of energy professionals, led by Dave Andrews, the supergrid idea is more than 50 years old, and was originally developed by geodesic dome inventor Buckminster Fuller.
Andrews says a fully nuclear system, would still require a supergrid. “If you were fully nuclear, you would also need the supergrid, but the issues would be in reverse − to spread the load out [during periods of excess production],” he says. “But why go for all the disadvantages of nuclear and gas when there are not overwhelming benefits? There are still unsolved problems and risks with nuclear.”
Andrews says: “A problem is that such a network does not necessarily benefit producers. We are obsessed with free markets, which is good for commodities but not for electricity networks. Our national grid would not have been built if left to private enterprise: producers prefer having captive audiences.
“When the public inquiry under Lord Weir decided in the 1920s that Britain should have a national grid, overnight half the power stations around the country were not needed. The supergrid will not happen on its own. We need the EU to coordinate this.”
Contrary to the Desertec concept, both Andrews and Czisch agree that wind power, not solar thermal, would be the backbone of any renewable system. Czisch’s research looked at the costs for the demonstration solar thermal plant in Spain and introduced the costs to his model. “I underestimated the costs by a factor of two, but the 1.6% figure is unlikely to increase,” he says.
Czisch modelled how solar thermal types of electricity generation altered with price, reducing the costs to an eighth of what they are now. There was no increase in use. “If you divide by two again, then photovoltaic (PV) use rises. I estimate prices of 25 euro-cents per KWh [for PV], but someone has to make a decision on how affordable electricity must be,” he says. Current costs for energy are between 6 and 7 euro-cents per KWh for wholesale electricity, making solar thermal sources very expensive.
The most compelling case
But for his most compelling case, Czisch examined how a renewable system could work using existing (actually 2001-2002) technology and prices − his base-case scenario. This assumed that the source countries in Africa would have their power delivered for free, and the rest would be transported to Europe using the supergrid.
Using his base case, Czisch estimates 1.1TW of wind power needs to be installed in the 67 countries covered by the supergrid. The cost he puts at £100bn to erect 100,000 turbines around northern Europe and western Sahara. But Czish himself doubts that this figure is meaningful. “Can you predict the cost of electricity 20 years into the future?” he asks.
Czisch says his model focuses on electricity prices on the open market, not absolute costs which are prone to changing markets and political forces. The surprising result is that renreable power generated in the Sahara would be cheaper on the European energy markets than existing power generation.
“I estimate the final costs to the consumer in my modelling to be 4.65 euro-cents per KW/h, which we can estimate − everyone knows what this means,” he says. The figure is less than wholesale electricity prices on the open market.
Technology has moved on since 2001-2002. “Each region now has a defined potential in wind etcetera, as well as better modelling of consumption. New wind turbines are giving higher generation rates. I assumed 1.5MW turbines, but now we have 5MW and 6MW turbines so the number of installed turbines should decrease and be installed on better sites. The turbines are more expensive but there is greater production,” he says. But isn’t such a vast roll out of renewable energy simply impossible? No, claims Czisch.
“I see no problem for huge growth in renewables. If you look at the financial close rates of the last 15 years, there is a growth rate of 40% − in the last years to expansions of 30GW a year. How long before we reach thousands of gigawatts? Perhaps we need only another 15 years or so.”
Work underway
Andrews has a different perspective. Similar rates of production have been achieved in the past so there ought to be no problem in the future. “In the Second World War we built 250,000 aeroplanes so what is the big deal? It is massive construction but it is possible,” he says.
While it is easy to think of the supergrid as a nice idea that may or may not happen, according to Royal Haskoning market manager for the UK and Europe Bev Walker, work is already underway to link national grid systems. “It is happening in particular markets. Consortia are coming together to link transmission networks. The transmission companies are interested because it will allow them to sell more easily across country national boundaries, but this work is developer-driven,” she says.
“The idea will gain more currency once power companies have more certainty about power sources − then the idea could snowball,” she says.
