Replacement Reserve Supply from Inverter-Based Generators in a 2030 Italian Scenario

Due to decarbonization objectives, generation fed with non-programmable renewable energy sources, and more broadly Inverter-Based (IB) generation, is expected to massively displace fossil-fueled thermoelectric generation in the future, and also to supply more and more ancillary services. With reference to a 2030 scenario for the Italian energy system, focus is here on the supply of Replacement Reserve (RR), via participation in the so-called “GR” services (in Italian) exchanged on the ex-ante stage of the Ancillary Service Market. Bidding for GRs is simulated for five IB technologies, i.e. ground PV, rooftop PV, rooftop PV supported by Battery Energy Storage Systems (BESS), onshore wind and offshore wind, considering various IB generation deloading levels with respect to the maximum expected power; bidding prices are chosen starting from the Levelized Cost Of Energy (LCOE) of the IB technologies. As deloading increases, the RR requirement, both upwards and downwards, estimated with a probabilistic procedure, decreases, and so do the energy exchanged for accepted GR bids and the associated economic exchange. For instance, the overall profit for Balancing Service Providers (BSPs) varies from 666.2 M€, for zero deloading and in the absence of bids from IB resources, to 85.7 M €, for 100 % deloading and in the presence of bids from IB resources. In the former case, the profit is all for thermoelectric plant BSPs, in the latter <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{6 9. 1 \%}$</tex> is for IB plant BSPs.