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Article RSE 15004444

Fossil fired power plants: are they needed for our future?


Nuova Energia ISSN 2036-8380, vol. 3, pp. 52-55, Maggio/Giugno-2015.

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L. Mazzocchi (RSE SpA)

GRID RESILIENCE 2015 - Security and vulnerabilities of the electrical system


The article deals with the issue of the future of thermoelectric generation in Italy, which is now declining as a result of the growth of renewable energy. The question is whether, in the medium to long term, there is still room for a significant share of gas and coal.A first and crucial consideration relates to the adequacy of the electricity system to cope with load peaks.

Taking inspiration from a scenario analysis, at the 2030time horizon, and assuming a peak load of 60 GW, it follows that, being impossible to rely on stochastic renewable energy sources, the sum of a) programmable sources available (coal assumed at current levels, gas cogeneration, hydroelectric and biomass), b) a reasonable share of stochastic sources (wind) and c) the contribution of imports , in 2030 we will still need about 13 GW of non-cogeneration combined cycles.

A second aspect by no means marginal is the flexibility of the system, increasingly necessary because of the growth of renewables. There are various flexibility tools (load management, storage systems, thermoelectric flexibility, based both on fossil fuels and biomass and geothermal energy), and in particular the contribution of thermoelectric on one hand appears indispensable, on the other hand today represents the option most readily feasible at minimum cost. For these purposes the amount of 13 GW of combined cycles, required for reasons of adequacy, appears redundant, in the medium term: half can be considered sufficient.

However the further growth of intermittent renewables, mainly photovoltaics, will progressively increase the need for flexibility, and it is therefore natural to imagine that the combined cycles fleet should become more and more suited to provide that kind of dynamic service.

Today only a fraction of the existing combined cycle capacity has remarkable flexibility; therefore it must be concluded that three actions should be planned: a) older plants closure (action already started), b) keep in service around a third of current plants, and c) invest what is necessary to obtain significantly more pronounced dynamic performances: faster startup, minimum load decrease, higher load gradients.

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