13 july 2010

Gregor Czisch on the super-grid

July 13, 2010 by FT Energy Source

The idea of a wholly renewable electricity supply, using a system that spans Europe and North Africa, is gaining ground.

There is scepticism, of course, about the variability of wind and solar power, and the cost of deploying the infrastructure. But several studies in the past year have shown how a good geographic blend of sources might make this possible, and perhaps even cost-neutral – and replicable around the world. Big energy equipment vendors are forming consortiums around both the Europe-African super-grid and ‘Desertec’, the idea of a massive solar project in the Sahara desert.

One of the earliest proponents of European/North African collaboration to switch to 100 per cent renewable electricity, and the ’super-grid’ to support it, is Gregor Czisch of Germany’s Kassel University.

Below, Czisch talks about his modelling of a transnational renewable energy system; why wind power would provide two thirds of energy in such a scenario; why renewables are better than nuclear, and how he views the reaction to his ideas, nine years later.

[This interview was carried out by Alessandro Colombo, an electrical engineer and patent official, and first appeared in Spanda Journal, published by the transnational NGO Spanda Foundation. ]

Your studies demonstrate the feasibility of a European electrical system supplied only by renewable sources. What are the main points of your proposal?

My proposal - derived from the results of my research - is to develop a large scale grid throughout Europe and Sahara - called super-grid - to interconnect wide spread different sites with electrical generators supplied by renewable sources, namely wind, solar, hydropower, and biomass.

In contrast with the smart grids, which represent a futuristic approach made of highly intelligent applications, the super-grid is already feasible with the technology available today, and serves to exploit in an optimal way the enormous potential of the renewable sources.

To demonstrate this possibility, I carried out from 1997 till 2004 a technical and economical systemic study. The first preliminary publication was in 2001. I analyzed the potential and the temporal behaviour of the renewable sources in all different locations worldwide and the corresponding unitary cost of the equipment for production and transmission of renewable electricity including all costs for operation and maintenance. The data for Europe and its neighbourhood were then fed in a huge mathematical optimization to calculate the optimal distribution and dispatch of all generators and transmission systems.

The main result for the base case scenario - only allowing to use existing technologies at current market prices (around 2001) - is that the most efficient arrangement is a system where two thirds of the electrical supply are provided by wind power, which is available in all areas but with different daily and seasonal behaviours (e.g. in Northern Europe the strongest winds are in winter, while in Sahara in summer). The super-grid indeed compensates the fluctuations of electricity produced in different countries and therefore is foreseen - as a result of the optimization - to strongly interconnect the sites of production and consumption.

The other sources selected to provide a mayor contribution are biomass (17%) and already existing hydropower plants (15%). Biomass and existing storage hydropower (not pump storage which only provides a minor contribution as backup) are mainly used as energy storage (the most important storage hydropower is existing in Scandinavian countries) and as backup when the production from wind power is not sufficient to meet the demand.

The role of the solar power from solar thermal power plants would be instead only marginal (1,6%), because the present technology to exploit the sun is very expensive compared to the other ones. In fact the cost figures for the solar thermal power plants in the scenarios might have been a bit optimistic. They have not been based on current market data since there was no new plant built for more than a decade. The first new commercial one was built in 2008 and the costs were twice as high as estimated for the base case scenario. Therefore it is unlikely that the optimization would have chosen solar thermal power plants if it would have “known” the real today’s costs.

Photovoltaic (PV) production is not selected by the optimization. To give a significant contribution, the cost of the PV installations should be reduced by 8 times compared to the costs figures of around 2001 or about 5 to 6 times compared to the today’s costs. Then the optimization finds a best solution that includes 4% of the electricity produced by PV applications only sited in the sunniest Sahara states. But this cost decline might be unrealistic. So even this small contribution might eventually never become part of a cost optimal solution.

The overall cost of electricity calculated for the base case scenario is 4.6 Euro cent/kWh. This can be compared to the 6-10 cents/kWh we are paying at the electricity market (EEX) for consumption shaped electricity today. This outcome is very encouraging: with a proper mix of renewable energies and a super-grid infrastructure embracing Europe, North Africa and smaller parts of Siberia, we can provide electricity to all countries at a lower cost than today, freeing the system from fossil or nuclear fuels and with no more substantial impact on the environment.

Isn’t the sun power more available than wind in Sahara?

Yes and no, the wind resources are tremendous in North Africa. I agree that in the common perception the Saharan region is normally associated with the sun resource, but at a closer look also the potential of wind energy is enormous. According to a recent study from the Harvard University, and confirmed by several others also my some years older studies, eight countries in the Sahara could individually generate the whole electricity need of Europe or some times more from wind power. Hereby no site is selected where the average load of the windmill was less than 20% of the rated power. Many sites are much better. So the potentials could serve with more than enough amount cheap electricity.

On the other side, the nuclear energy seems to be even cheaper, at 2 cents per kWh, according to its supporters. Is that realistic?

The figures for the nuclear energy are under serious debate. The nuclear power stations need a huge investment for their construction and a long working time for their amortization. This creates the need to run the plants continuously at full power, “until it breaks into pieces”, and only then the average cost of the generated electricity can decrease more or less to the variable costs of 1.5-2 c/kWh if we neglect the debate about the costs of insurance and the long term cost of nuclear waste disposal.

Nuclear plants are therefore used to mainly cover the steady base of the demand of electricity. But if the use of alternative sources like wind power expands also a growing part of the base load band will be provided by them, the nuclear plants would no longer be run continuously, the initial investment is recovered more slowly, and the average production cost increases.

In other words, nuclear plants are more or less incompatible with an increasing quota of renewable generation. An intelligent strategy of investment should privilege instead other flexible and adjustable types of generation, which can perfectly work with the variability of alternative sources. The existing nuclear stations should be gradually phased out and no new ones should be built.

How was the reaction from the scientific community and the political level to your proposal?

After almost nine years from the first publication of the results and a large number of presentations in conferences and papers, I consider the reaction too cold and too slow.

This has to do with the political positions, and the interests involved. In Germany for example we have three main strategic directions with regard to the energy issues.

First, the coal lobby, which is strong both in the right and the left-wing parties like the SPD, and promotes the construction of new coal power plants more or less ignoring the climate impact.
Secondly, we have the supporters of nuclear power, equally strong and well connected to the utilities and also with some background in different parties.

At last, there are the opponents of both of them, which can be identified in the “green groups” across the several parties. They often promote a vision of “beautiful” small-scale installations, a sort of decentralized autarchic model, and are supported by manufacturers and installers as the ones of solar panels.

Such an approach, even if perceived as alternative to the traditional system, can never really compete with or hardly replace the big nuclear or coal industry, and therefore allows for their long-term permanence.
Decentralists oppose even the construction of new power lines, which are also needed to transport energy from wind power within the national borders.

They think of an ideal like every house supplied by its own solar cells and independent from the network, but that in the best case leads to very expensive supply with poor energetic efficiency.

Who are the parties supporting your scenario?

My proposal received strong support throughout most political parties, either officially or indirectly. I have been invited to many hearings, like at the German ministry of Economy, to discuss the law for the acceleration of the construction of transmission lines [Energieleitungs-ausbaugesetz], as well as in the EU parliament, where I presented my results firstly in 2004, or in conjunction with the Baltic sea parliamentarian conference, leading to a resolution for the construction of HVDC lines (High Voltage Direct Current, an old and modern technology used to transmit electricity to very long distances, above 800 km). In 2009 a new EU directive was issued, to allow the import of electricity generated from renewable sources from non-EU countries, in order to arrive at the aimed quota of 20% of the EU energy consumption provided from renewables by 2020.

These regulations are consistent with the Super-grid idea.
Also the industry is now drawing attention to the super-grid thanks to the Desertec Industrial Initiative, joined by major energy groups like RWE and EON. I initiated this idea since I contacted the main driver the Munich RE in 2005. Now the result is - a bit different than I tried to communicate - based on large solar thermal installations in the Sahara Desert, with the electricity transported to Europe by HVDC lines. So again we see parts of the super-grid.

Unfortunately the solar thermal technology is not mature enough, it is still expensive in comparison to wind power (15-20 c/kWh against 3-5 c/kWh for wind energy) and would take too long time to develop to a major source able to help to avoid the worst effects of the climate change in time.

In 2008 we have had only 100 MW of new solar thermal plants, while the new wind generators amounted at 27.000 MW in the same period, almost 300 times more, and growing constantly by 30-40% per year.

I don’t know why Desertec Initiative focues on solar plants, but a guess is that they don’t really foster a quick transition to alternative sources, since they represent the industrial groups and utilities that also run the existing traditional plants.

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