Abstract for 
Uppsala, Sweden, May 23-25, 2002
Organised by Uppsala University and ASPO,the Association for the Study of Peak Oil

Considerations on Renewable Electric Energy Systems 
by professor Mats Leijon 
Div of Electricity, The Ångström Laboratory, Uppsala University, Sweden 

Most renewable electric energy systems of today focus on unregulated energy production like solar and wind power. However, if we still want to use electricity when we need it and not at the will of nature, we must be able to regulate power. 

The question of regulating power is of significant importance in all energy systems. Today the only renewable energy that has regulating capability is hydropower provided by river dams or pump stations, and it is used to regulate peak loads. Tomorrow it will have the additionally feature of regulating sources like wind and solar power as well as other unregulated sources. In countries with little or no access to regulating hydropower, gas turbines are used in an equal function.

Therefore itís important to differentiate between units with peak power/regulating capability and units with only energy production/non-regulating cap ability, since all discussion regarding unregulated renewable energy production will only be theoretical if we neglect the peak power problems. 

The other consideration is from a democratic and thereby an economical point of view. In the Nordic grid electricity prices have been rather low compared to other parts of the world. During the last few years, spot prices have varied between 0.5 cent/kWh to 2.5 cent/kWh. In the search for renewable alternatives, it can easily be argued that sources with low energy production per install power rating always need subsidies to be economically feasible.  Is this, at least in the long run, the best way to use taxpayersí money? Most would think not.

Therefore, the technological development of renewable unregulated sources cannot be driven by political decisions alone. In the long run, it also has to be run by economical drivers. By looking at the utilisation factor for different renewable sources it can, from a pure economic point of view, be concluded that several of the ones that is discussed today, stance a small chance to be successful without subsidies. However, there are several yet undeveloped sources of power like geothermal, sea based wind (offshore), ocean wave energy, underwater currents and possibly other sources that has a large energy production potential per installed power rating and thereby also satisfying the boundary conditions of future sustainable complement in the electric energy production.  

Keywords: Renewable Electric Energy, Hydro, Peak power, Economy, Utilisation, Wind, Solar, Ocean, Wave, Underwater stream.

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