Marine PSP (Pumping Station Plants)

By F. Lempérière (Hydrocoop) ____   Summary: At present the hydropower plants have a total capacity of 1 150 GW and generate yearly 4 000 TWh associated with 18 000 TWh of coal or gas electricity. In 2050, Hydro Power plants may reach 2 000 or 2 500 GW generating 7 000 TWh associated with some 40 000 TWh of variable wind or solar energy. Storage of electricity by Pumped Storage Plants (PSP) may be justified up to 3 000 GW capacity instead of 150 GW at present. The utilization of rivers and reservoirs should be optimized accordingly between hydropower generation and storage. It may be very different from the present utilization.   Hydropower is presently associated with large amounts of fully-dispatchable coal or gas electricity. By mid century hydropower will be associated with much less coal or gas and much more variable wind or solar energy; it may thus be as useful for guaranteed capacity and energy storage as for generation. The best utilization of rivers and possible reservoirs should be reconsidered accordingly.   Three questions must be answered: How may the global energy and electricity landscape look like in 2050? How useful will hydropower be for generation and storage of electricity? What role may pumped storage plants (PSP) play in this context?   The global energy and electricity in 2017 and 2050   All energies are assessed in kWh (or in TWh = 1 Billion kWh) All power capacities are assessed in kW (or in GW = 1 million kW) Costs are assessed in US $ and in cents of US $ per kWh   1.1. Energy in 2017   The total “primary energy” used yearly is of 15 billions tonnes oil equivalent. This is equal to 175 000 TWh, i.e. 25 000 kWh per capita for 7 billion people.   A “primary energy” of 10 000 TWh is included in fuels (mainly oil) which are not used for energy but as feedstocks for various industrial products, notably chemicals. 65 000 TWh, mainly coal and gas, are used for generating 25 000 TWh of electricity and 40 000 TWh are turned into low-temperature heat in thermal plants, most of it useless. 100 000 TWh are used directly (not through electricity): 45 000 are from oil mainly for transport, of which over 30 000 are lost as heat in motors and vehicles, 35 000 are from gas and coal of which 5 to 10 000 are lost, 20 000 are from biomass and various sources and 10 000 are lost (for instance, most primary energy is wasted in traditional utilization in Africa or Asia). The total losses are close to 50 000 TWh and the useful energy is about 50 000 TWh   The total useful energy, i.e. the satisfied needs, is thus 25 000 + 50 000 TWh = 75 000 TWh in 2017 (10 000 kWh per capita). About 60 000 TWh are from fossil fuels.   1.2. Energy in 2050   The world population will increase by 40%, the extra needs are enormous in many countries and electricity will be available in all countries at a cost close to today’s and possibly lower; it will be mostly renewable. The global economic product will probably double between 2017 and 2050 and the useful energy will increase by at least 50%, reaching 110 or 120 000 TWh/year[1] The primary energy which is presently 75 000 TWh useful + 100 000 TWh lost may be in mid-century: 110 or 120 000 useful + 50 000 TWh lost, i.e. will not increase. The share of electricity in useful energy which is presently one third may well be two thirds by mid-century for 3 reasons: It is possible to use electricity for almost energy needs except a significant part of transports (liquid fuels)...

Maintaining the present world rate of economic rate progress over the next 50 years will require five times more energy than is available at present. Meanwhile, the use of fossil fuels, which at present supply about 80 per cent of needs, should be reduced to about 10 per cent. The short fall could theoretically be made up by using just 20 per cent of wind potential and a small amount of solar photovoltaic potential (these sources could supply much more than 50 000 TWh/year, compared with the present total of 15 000 TWh/year).But they are intermittent and would require a vast storage capability. Large offshore basins, based on proven technologies, could store 5000 x 10p9 m3 of sea water, the same as currently stored in hydro reservoirs. They could be used several times a week, according to the shortfall in wind or solar energy supply. Such valuable ‘green’ offshore structures, which could last for centuries, deserve the name ‘Emerald Lakes’.