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Capacity of green alternatives five times world power consumption.
The (near) commercial world capacity of the Green options of electricity production, Wind, Solar, Hydro, Tide, Wave, Bio and Geothermal energy is if exploited equal to five times the current world use of energy today and twice the likely energy used in year 2100. The theoretical non commercial capacity could be twenty times this amount. The problem of most green options is intermittency which can only be overcome by diversity, power storage and transmission; all which increase cost.
An overall sketch of power flows for the ' pure green' solution which may come about when all fuel is exhausted on the planet, is illustrated in the sketch below.
However to supply the world without the fossil fuels coal, gas, oil and also without nuclear power and without methods of dealing with carbon would seem impossible in the few years remaining and necessary to limit emissions.
The only practical immediate solution, which includes nuclear, CO2 collection & storage, quick development and commercialization is sketched out on the future page. (see statement in RH margin also.)
Thickness of lines is an indication of the amount of power transferred.
COMMENT Many solar options, wind, tidal, wave are intermittent and remote from demand locations, so high voltage transmission will play a major part, plus local storage.
While solar theoretically could meet every power need, tidal power could meet all UK's need, geothermal all the need in some areas/countries, certain materials and costs will impose limits. Nearly all green sources of energy above are intermittent. Direct solar power is available for up to 50% of the time, wind for 30% mostly and tidal for 60 to 70% of the time. Therefore a mix of types of generation plus diversification via transmission should provide the right solution to power needs.
A worldwide dc transmission system may be necessary from power production areas and between time zones and/or hydrogen generation and storage on a wide scale and use of acceptable diversification between types of generation and different locations.
To supply the whole world with green power (without nuclear or fossil fuel in any form) would take a long time to implement and so in the meantime nuclear fission and carbon capture and storage will also be necessary to reduce CO2 emissions.
In the long term nuclear fusion might transform the picture. However at present it seems that fusion reactors will be expensive if they prove to be practical, in addition to which they require considerable energy input (10MW and above) to start up so other forms of large scale energy will always be necessary on the transmission systems. By the time fusion arrives, solar, wind, tidal, wave, hydrogen storage etc could be so well developed that these green systems are cheaper and the preferred means of power.