Transitioning to a low-carbon energy system requires the input of very large amounts of renewable energy, including intermittent wind and solar power. To ensure sufficient power is available, clean energy needs to be stored so it can be dispatched when needed to meet demand. Lithium-ion batteries are the most popular system at present, but they only are for short-duration storage, that is, six hours or less. However there is also a strong ecological and business case for long-duration storage and the current front runner is green hydrogen, made from renewables.
Mitsubishi recently did a survey and these were some responses: 54% of participants who work for utilities (or other organizations that can directly deploy energy storage) said they needed storage that was dispatchable for eight to 24 hours at a time. Also, 35% said they needed to dispatch stored power for more than 24 hours at a stretch.
Utilities can put green hydrogen to use today with hydrogen turbines currently on the market. Initially, these turbines use a blend of natural gas and green hydrogen — but as they evolve, the fuel blend will move to 100% hydrogen as hydrogen supply and infrastructure advance. Long-duration energy storage could prove especially helpful for utilities affected by bad weather or natural disasters lasting days at a time, which can trigger extended outages and rolling blackouts. Whenever resource adequacy is challenged, long-uration energy storage supports power reliability without compromising progress toward decarbonization targets.
The US DOE announced its Energy Earthshots Initiative second target in July 2021: the Long Duration Storage Shot will spawn innovation to reduce the cost of utility-scale, long-duration energy storage by ninety per cent within a decade. Alongside this government program, many utilities are making their own large commitments to hydrogen-fueled generation. These investments, in turn, are likely to spur the expansion of hydrogen infrastructure and drive down the cost of green hydrogen (currently about $2.50/kg).
Long term energy storage will be essential to managing loads in the future, when fossil fuel and nuclear plants are being closed down, and their baseline power will have to be replaced on the grid.