Why would long duration energy storage (LDES) make renewable energy exponentially more valuable to utilities?
With the potential to store power for days or even weeks LDES could finally allow renewable energy to contribute to key utility ancillary services. The key is its ability to balance the variability of wind and solar LDES makes renewables dispatchable hourly and seasonally to match load demand.
Utilities have numerous issues to content with including an increase in supply demand imbalances and growing transmission congestion. LDES can help alleviate these issues while also offering other ancillary services such as blackstart (restarting after a black out), load following, synchronous inertia, and frequency response.
I know, that’s all Greek to the average person but not to those who responsibility is keeping the grid functioning 24/7.
But current utility transmission and distribution planning doesn’t factor in the value LDES brings to these services. That needs to change.
Types of LDES technology
- Thermal: Store energy thermally to release electricity and heat. Concentrated solar power heat molten salt or liquid metal in an insulated environment using a heat engine to convert the heat into electricity.
- Mechanical: Stores gravitational potential or kinetic energy. An example is pumped storage hydropower (PSH) which has been around for over a century. It uses two large reservoirs at different elevations. To charge, a water pump moves water from the low to the high reservoir. Discharging involves gravity forcing water through turbines to generate electricity.
- Electromechanical: Batteries of different chemistries that store electrical potential energy. Iron flow uses iron electrolyte with different charges stored in separate tanks.
- Chemical: Store energy in chemical bonds – Form Energy which has attracted $800 million in investment capital uses a chemistry known as reversible rusting. When discharging the battery “breathes in” oxygen and converts iron metal to rust. In the charging cycle an electrical current converts the rust back into iron. The company claims its battery can store power for 100 hours.