Electrofuels and curtailment of wind and solar power

Abstract:

Generation curtailment and low or negative electricity prices are appearing more frequently with increases in installed capacities of wind and solar power. There is a potential economic opportunity to use this intermittent excess electricity generation capacity. Previous studies show that least-cost electric power sector models with substantial fractions of intermittent renewable power can reduce curtailment and experience substantial system cost reductions when coupled to other energy sectors with temporally flexible loads.

We construct a least-cost electric power system model coupled to a generic temporally flexible load to study the availability of low-cost and otherwise curtailed electricity for this load and the cost-sharing benefits of a coupled system. Specifically, we model a zero-carbon emission electric power system producing a synthetic low-carbon drop-in gasoline replacement (an "electrofuel"). We use a simple parameterization of the electrofuel production process to keep the model generic. While holding the demand from traditional electricity services constant, we vary the fraction of energy delivered to the flexible load from 0% to 99% of the total delivered energy.

When demand from the flexible load is relatively small, there is excess power generation capability at most hours. This allows the temporally flexible load to take advantage of available generation capacity. As the flexible load increases, additional generation capacity must eventually be added to the power system allowing cost-sharing with the traditional electricity demand. Consequently, as the flexible load consumes a greater fraction of the total delivered energy, the cost per kWh of meeting electricity demand decreases (by as much as 54% in our scenarios), while the cost of producing electrofuel increases (up to 90% in our scenarios).