Dave Elliott: As variable renewable expands there are issues in relation to maintaining security of supply, which will add to the cost of a sustainable energy system. But, as bit of post-Christmas cheer, in this brief post, can I point to a recent Imperial College study that says power grid balancing costs for variable renewables are low at low penetration, and can even be negative. And although they can be higher at over 50% shares, depending on how balancing is done, total system intergration costs need not be excessive- at most €30/MWh, even at 85% penetration. Reviewing existing data, Dr Phil Heptonstall and Prof. Rob Gross from Imperial College look at grid balancing costs, focusing on operating reserve costs, the costs of the unpredictability or incorrect forecasting of variable renewable energy (VRE) output over short timescales (seconds to a few hours) and the capacity adequacy costs associated with the extent to which VRE output can be relied upon to meet times of peak demand over the year. They also try to look at total system costs, including so called ‘profile costs’, but say that its hard to come up with reliable figures: ‘Double counting with reserve costs is possible in all instances, as the same capacity may provide reserve services, serve net loads and meet peak demands’. It is also worth noting that grid balancing systems are developing fast, so that costs should fall. For example, green hydrogen production and storage using zero cost surplus renewable output offers a way to balancing long lulls and although some balancing system may add to the cost as the Imperial College paper notes, some may actually reduce power costs.
Renew Extra 26th Dec 2020 read more »