Some comments on the future world energy
June 2011, F. Lempérière
The key problem is the possibility to get mid century the energy necessary for the world development at acceptable cost and impacts with 70 or 80% of renewable energies (essentially solar, wind, hydro and biomass).
In 2050 a population of 9 billion (7 in sunny countries) will have probably a gross product 3 or 4 times the present one with a reduced energy intensity; the need of energy may be the double of the present one.
The Primary Energy is not an useful reference for most 2050 sources: for instance closing a thermal or nuclear plant supplying 1 TWh and generating 2 TWh more by wind, PV or hydraulics double the Final Energy when reducing the Primary Energy.
Presently the Primary Energy is close to 150.000 TWh/year and the Final Energy utilisation to 100.000 TWh. But the present need of Final Energy is lower because many utilizations could use other sources reducing the relevant Final Energy: as examples using PV for cooking in Asia or Africa should divide by over 5 the relevant final energy and using electric cars could divide the Final Energy for transports by 3.
The need of Final Energy in 2050 may thus be between 150.000 and 200.000 TWh/year.
Anyway the final energy used from many sources will be limited:
Oil and gas 20 to 40.000
Hydraulic 6 to 8.000
Nuclear 2 to 6.000
Biomasse and Geothermy 20 to 40.000
i.e. a total probably between 60 and 90.000 TWh/year, much under needs of 150.000 to 200.000 TWh/year.
There is thus a great uncertainly but it is very likely that the gap will be mid century in the range of 100.000 TWh/year, to be met by coal, wind or solar, essentially through electricity.
Electricity will be close to 100.000 TWh/year, with 20.000 from hydro, nuclear, oil and gas and the balance: 80.000 from coal, wind and solar.
It is possible to get quite all from wind and solar under 4 conditions:
– Coal resources could supply up to 50.000 TWh/year along most of the century at a direct cost lower (before 2040) than solar power by few cents per KWh (at least before 2030 or 2040), i.e. a saving which may be possibly 0,5 or 1% of the gross product. This should be then avoided either by the cost reduction of solar energy, or a Carbon Tax, or imposed storage of CO² from coal plants.
– Financing of renewable energies in poor countries will require help from richest countries.
– The total area occupied by wind and solar energies may be close to 1 million km², of which possibly half in desert areas. This seems progressively acceptable.
– Intermittent energies will require storage. This may be solved by some thousands GW of P.S.P. occupying under 50.000 km² of lakes.
Getting mid century 80% of energy from renewable sources seems thus possible at a very acceptable cost but their implementation will probably be rather slow up to 2030, especially because solar energy optimization requires 10 to 20 years. The huge increase should thus be probably between 2030 and 2060, to be prepared well in advance. The choice of renewable will vary according to countries but most world areas have much solar, wind or hydraulic resources and electricity transport along few thousands km is realistic.
Nuclear energy will probably not supply over 5% of needs before 2050. Progresses in breeders could increase this share in the second part of the century but will probably remain lower than wind and sun energy.
An average cost of 10 cents/KWh for energy generation, storage and transport seems likely. As the energy intensity will be much reduced, the share of Gross product devoted to energy will be about the same as now.
If needs are higher than foreseen above, they may be met by extra solar and wind energy and relevant energy storage by P.S.P. as far as necessary.