Storage on the Bulk Power System
The flexibility of energy storage offers a range of benefits for the efficient and effective operation of the bulk electricity generation and transmission system. Energy storage improves the efficient operation of the grid, reducing congestion on the grid at peak periods which causes line losses (and can also prevent distant renewable energy getting to end users). Energy storage can also reduce the need to build additional power plants to meet rare system peak demand situations.
Generation from large-scale renewable energy systems doesn’t naturally follow the precise needs of energy users the way that powering a fossil fuel plant up or down can. But energy storage systems are ideally suited to match the generation from renewable sources to users’ energy demand: storage systems can absorb surplus energy when generation exceeds demand and release it when generation drops below what is needed to serve energy users. Without storage, excess renewable generation must be ‘curtailed,’ and without storage, shortfalls in renewable energy supplies must be met with traditional sources of energy like natural gas peaker plants.
Challenges Posed for Grid Operations
Aging transmission lines designed for out-of-date generation and consumption assumptions can pose challenges for grid operations as lack of adequate capacity can prevent enough power getting from where it’s generated to where it’s consumed. This is particularly relevant for large renewable energy projects – like wind farms – distant from population centers that rely on the capacity of long transmission lines. Existing transmission infrastructure may not be able to keep up with today’s needs. Energy storage can solve this challenge by shifting transmission of renewable energy to times when lines are less congested. It can be sited near generation to hold on to energy until the transmission constraint subsides (thus avoiding curtailment of generation) or sited close to load to allow the power to be moved near that load before congestion periods. Storage systems are also likely to attract less public opposition than new, highly visible power lines with lengthy rights-of-way passing through multiple jurisdictions that might raise objections to their siting.