In my talk I will introduce you to some the worldwide potentials for renewable electricity production. The techniques we will discuss are electricity production via solar thermal power plants and hydropower and finally we will focus on wind energy. For each of these options of power generation I am going to point out the characteristics with regard to their specific temporal behaviour and the costs to be expected. We will see that the temporal behaviour significantly changes with the size and the selection of the catchment area used for the power generation. We will also touch on the topics of backup and storage needs, the subject of grid capacities and of cause the question of electricity costs. After this we will come to economically viable „Scenarios for a Future Electricity Supply“ * based 100% on renewable energies. It will be shown that a change to a totally renewable electricity supply is neither a technical nor a economic problem but mainly a political task.

• Background Information:

Szenarien zur zukünftigen Stromversorgung - Kostenoptimierte Variationen zur Versorgung Europas und seiner Nachbarn mit Strom aus erneuerbaren Energien https://kobra.bibliothek.uni-kassel.de/handle/urn:nbn:de:hebis:34-200604119596 Low Cost but Totally Renewable Electricity Supply for a Huge Supply Area http://www.iset.uni-kassel.de/abt/w3-w/projekte/LowCostEuropElSup_revised_for_AKE_2006.pdf

On this slide you can see for example the ratio between the average electricity production in December and July. As it is the case for the PV electricity production, at the southern Sahara we find that the production only changes slightly over the months while the variations increase much stronger going to higher longitudes.

For example the Net Transfer Capacities from Morocco to Spain with its 400 MW and the 1100 MW from Spain to France would not allow high power transfer even if the capacity soon is enlarged to 1400 MW between Morocco and Spain.

But there is a solution. High Voltage Direct Current Transmission (HVDC = HGÜ) is a technology used since many decades for transmission of huge amounts of electricity over far distances at very low losses and low costs.

Using today's High Voltage DC (HVDC) technology to transport the electricity to Europe (e.g. Kassel GER) the costs of electricity would even for the farest distance mentioned only increase by 30%. The underlying economical assumptions for HVDC technology are shown in the lower right table.

The costs of electricity in Kassel do not seem to be very unreasonable. The option to import solar thermal electricity from Northern Africa to Europe becomes even more interesting, if the investment costs for solar fields, the most costly part of SEGS power plants, will reduce. An reduction to roughly 50% of the today's field costs is expected as soon as a capacity of 7 GW of SEGS is erected world-wide. This will reduce the costs of electricity in Kassel to approx. 60% or below 6 €ct/kWh.

Here it is worth to distinguish between two types.

The river runoff type uses the water at the time it runs down the river and normally has no or just very little storage capacity.

The storage type sometimes can store the water which is running into its reservoir for many months (see following table). So this kind of power plant decouples runoff and electricity production and thus gives the degrees of freedom necessary to be used as back up to balance the variation of other production facilities and of the demand.

At Inga at the river Congo there is probably the location where the biggest hydropower plant world wide could be erected.

It is possible to be quite selective and choose only the better regions. As an example I selected the following.

1. Good wind sites within EU & Norway. (With restrictions due to the high population density.)
2. The Jamal Region with northern Russia.
3. Parts of Kazakhstan
4. Southern Morocco (The calculated production is rather conservative. Due to measurements in this region significantly higher production up to 5000 FLH is expected.)
5. Mauritania also has good wind conditions.

To use these potentials we have to have high transport capacities.

Comparing the monthly mean wind power of the selected European regions and the Demand of the EU & Norway one can see that the fluctuations of the production varies much more than the demand. Europe is a typical winter wind region with maxima in winter and minima in the summer month.

This shows the black line which represents a combination of of the five selected regions.

But not only the long term behaviour changes with the size and selection of the catchment area.

Now let us consider we produce the equivalent of the demand from wind Energy.

For the demand EU & Norway we need to install 660 GW to within all regions.

The duration curve of the hourly electricity consumption depicted in the slide represents a total rated power of 465 GW and a demand of 1940 TWh. The maximum power demand is 295 GW, the minimum about 140 GW.

The duration curve of the difference between wind power production and demand is shown in the green line. The maximum power surplus and lack are each roughly 200 GW. The lack of energy amounts to 14% of the demand.