Load Management – Strategies for Dealing with Temporary Oversupply of Variable Renewable Electricity

Abstract

The Netherlands is currently in the process of massively increasing electricity generation capacity from wind and solar energy in order to meet its target of 20% renewable final energy consumption in 2020. As a result of large installed capacities, intermittent electricity production could temporarily surpass demand. If the phenomenon of excess electricity is not addressed, free and renewable electricity will be wasted as the generation from wind turbines and solar panels will have to be curtailed. This study examines technologies that are designed to absorb temporary oversupply from volatile renewables and convert it into useful energy. Three examples of conversion technologies are investigated, each representing one of the categories power-to-power, power-to-heat and power-to-gas conversion. A model is built that forecasts excess electricity as a function of installed volatile generation capacity. It is forecasted that The Netherlands will be confronted with 2 TWh of excess electricity in the year 2020, if the target of installing ~17 GW of wind and solar energy is reached and other options of dealing with oversupply are not available (e.g. export). Technologies that only convert excess electricity will run at a very low load factor (typically below 10%) in 2020 because excess electricity is only available for 1000 hours throughout the year. In consequence, the conversion technologies have rather high levelized cost and none of them is expected to be profitable in 2020. Nonetheless, there are considerable differences in technology performance: Power-to-heat performs well in 2020 and would cause the least expenses. Power-to-gas conversion will be too expensive in 2020, but is generally suitable to reduce curtailment. Power-to-power conversion does not seem suitable for reducing curtailment, because of high costs and a limited storage volume. It is unlikely that curtailment will ever be avoided completely by the technologies discussed here, as the reduction of curtailment follows the Pareto principle: The first installed conversion units have a large effect, while the complete reduction of excess will call for unreasonably large conversion capacities.