Aktionen

Lecture Magdeburg 2001 - Overview

Aus Transnational-Renewables



Global Renewable Energy Potential

- Approaches to its Use -

held in Magdeburg, Germany on September 2001

VM2001 slide1.jpg In my talk I would like to introduce you to the worldwide potentials of renewable electricity production. The techniques we will discuss are electricity production via photovoltaics, solar thermal power plants, hydropower, biomass, hot dry rock geothermal power plants, energy towers 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 and the subject of grid capacities. After this I consider wind energy as major source of power production. And last but not least we will reflect on a possible combination of climate protection and development aid.

VM2001 slide2.jpg Let‘s start with photovoltaic electricity production.
VM2001 slide3.jpg Here you can see the potential production of PV panels mounted in such a way that the orientation of the surface is parallel to the latitude and has a fixed slope equivalent to the latitude towards the sun. The output is calculated from data of the European Centre for Medium Range Weather Forecast (ECMWF) and additional data from the National Centre for Environmental Prediction (NCEP). (The panels are considered to have an efficiency of 14 % at peak radiation and standard temperature reduced to approx. 13 % efficiency due to system losses.)

The best conditions are found in arid zones of high mountainous regions. Here the potential production is more than twice as high as we can expect in middle European countries. In Poland the production of a photovoltaic system will lie in the range of 130 kWh / (m² a) or approx. 900 Full Load Hours (FLH).

VM2001 slide4.jpg The seasonal variation of power production from PV panels is significantly lower at lower latitudes. On this slide you can see for example the ratio between the average electricity production in December and July. In the southern Sahara we find that the production only changes very slightly over the months while in Europe the winter production is only a small fraction of the summer production.
VM2001 slide5.jpg Here the European conditions are shown. The seasonal variation of power production from PV panels for example in Northern Germany as well as in Northern Poland in December reaches only 10 % of the production in July. In Southern Europe the seasonal fluctuations are significantly lower.
VM2001 slide6.jpg The monthly variation of PV power production can be studied in more detail comparing the different graphs on this slide. They show monthly averages for selected regions contrasted with the electricity consumption of the member states of the EU.

In this example only the production of Mauritania and Senegal in the Southern Sahara show a monthly variation similar to the mentioned electricity consumption. Within all the other regions the behaviour more or less shows an anticyclical pattern compared to the demand.

VM2001 slide7.jpg With the underlying economic assumptions shown in the upper table the costs of PV electricity production at some selected sites are calculated and the results are listed in the lower table.

The costs of PV electricity production are relatively high, so that at the today's investment it seems to be an option for rural areas with high potential and without grid connection where it competes with other sometimes even more expensive techniques.

VM2001 slide8.jpg Here you see a view of a solar thermal power plant which leads us to the potentials of this kind of electricity production. The direct solar radiation is concentrated in parabolic troughs to heat up a fluid that is used to power a conventional thermal power plant. Dependent on the design of the power plant the heat is used with an efficiency between approx. 32 and 38 % to produce electricity.
VM2001 slide9.jpg Here the potential heat production of the solar field of a SEGS power plant is shown. Very good conditions are found in the Sahara where the potential electricity production is more than 500 times the electricity consumption of the EU member states.
VM2001 slide10.jpg The seasonal variation of power production from SEGS power plants is significantly lower at lower latitudes.

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, in the southern Sahara we find that the production only changes slightly over the months while the variations increase considerably going to higher longitudes.

VM2001 slide11.jpg The monthly variation of power production from SEGS power plants can be studied in more detail comparing the different graphs on this slide. They show monthly averages for selected regions contrasted with the electricity consumption of the member states of the EU.
VM2001 slide12.jpg The European electricity network within and especially between the countries is too weak to transport significant amounts of electric power from distant regions with good conditions for renewable electricity production. This is also true for the connection to Africa.

For example the Net Transfer Capacities from Morocco to Spain with its 350 MW and the 1100 MW from Spain to France would not allow high power transfer. But as e.g. can be seen from the calculations presented in the next slide the construction of new transport capacities using today's technologies economically seems to be quite feasible.

VM2001 slide13.jpg With the underlying economic assumptions based on today's technologies and prices shown in the upper right tables the costs of solar thermal electricity production are calculated for some selected sites. The results are listed in the table on the left side.

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 furthest 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, are reduced. A 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 12 DPf/kWh.

VM2001 slide14.jpg Now we come to hydropower. Here it is interesting 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 runs 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.
VM2001 slide15.jpg This table shows the rated power, the storage capacities and the annual energy production of Storage Hydroelectric Power Plants in Western European Countries. The storage capacities are close to 10% of the total electricity production within all the member countries of the EU.
VM2001 slide16.jpg Today 19% of the world wide electricity production is from hydropower. Siemens expects that this fraction will slightly decrease since the estimated growth of the demand with 2.8%/a is higher than the estimated growth of electricity production from hydropower.
VM2001 slide17.jpg Siemens estimates that within eastern and middle Europe about half of the economically exploitable hydropower potential already is exploited. Within CIS (Commonwealth of Independent States) still very high potentials are available.
VM2001 slide18.jpg Most of the unused Russian economically exploitable hydropower potentials are in the eastern parts of the country, but even within the European part some remarkable potentials are left.
VM2001 slide19.jpg Within Africa the economically exploitable hydropower potentials are also very big. Possibly the best site worldwide for hydropower is close to Inga at the Congo river. Lahmeyer International estimates that the runoff at the best position for the power plant is sufficient to deliver 38 GW of electrical energy more than 355 days per year. The costs for a power plant with some GW Rated power could be approximately at 1000 DM/kW.
VM2001 slide20.jpg Now we come to electricity production from biomass.
VM2001 slide21.jpg In the upper table biomass potentials estimated by Thomas Dreier ("Lehrstuhl für Energiewirtschaft und Anwendungstechnik, Technische Universität München") are given. The secondary biomass potential is the potential of residues and waste, while the total potential includes the possible biomass production on unused land and within western Europe also 15% of the today's farm land is considered to be usable for this purpose.

Assuming an efficiency of 30% for biomass power plants the secondary resources would be sufficient to e.g. deliver roughly one third of the annual Polish electricity consumption. The lower table exemplary shows a calculation for cost of electricity from Biomass.

  • The investment costs are quite strongly dependent on the efficiency of the power plant, on the environmental standards within each country and on the size of the plant. The given costs may fit for German conditions.
  • The fuel costs strongly also vary. E.g. some residues are much cheaper than the given example others may have negative costs since they contain substances harmful to the environment (This again could strongly influence the investment costs). The given prices of 2.4 DPf/kWhth are consistent with today's firewood prices and can even be achieved by biomass production for energetic purposes.
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