Our energy supply system finds itself in a transformation over to a far greater share of renewable energies. Though some have been fooled into believing the transformation can be done completely in just a matter of a few years, sobriety tells us it’s going to take considerably longer, and batteries are not the answer to the supply volatility problem.
Battery storage “still needs to demonstrate that it eventually can become cost-effective and reduce its significant ecological footprint,” says Dr. Sebastian Lüning.
Wind and solar energy’s high supply volatility require mass storage capacity whose solution remains off in the future. Chart above depicts Germany’s demand and supply by wind in sun.
What follows is the abstract of a review of renewable energies (starts on page 204) by Dr. Sebastian Lüning (emphasis added).
As the share of renewable energies keeps rising in the global energy mix year by year, volatility of wind and solar energy sources needs to be carefully counterbalanced with adequate Electrical Energy Storage (EES). Suitable storage solutions need to have mass storage capacity to supply whole countries for several days to weeks during renewable supply gaps. At the same time, storage needs to be cost-effective and full-cycle energy losses need to be minimized. Stimulated by the wish to achieve decarbonization as quickly as possible, significant research efforts are currently underway worldwide to come up with solutions to the energy storage challenge. This article summarizes the most promising technologies to fill the EES gap, highlighting advantages, challenges and chances of mid-term technological breakthrough. In order to facilitate the discussion, the storage technologies are grouped here into the following categories: (1) Rechargeable batteries, (2) Pumped hydro energy storage, (3) Power-to-gas and power-to-liquid, (4) Compressed air, (5) Thermal, and (6) Flywheels.
Whilst all technologies will be useful for specific applications, artificial fuels (power-to-liquid and power-to-gas) appear particularly promising to take the energy transition to a new level. Artificial fuels can be stored and transported using established transportation logistics from the hydrocarbon industry. Systems are easily upscalable so that renewable supply gaps of several days or even weeks can be effectively bridged. Artificial fuels can be exported to customers over great distances without major losses, opening up the chance to not only capture surplus electricity for domestic storage but also to specifically produce energy for the export market. The latter applies particularly to sun- and wind-rich regions.
A second promising technology for the energy transition is thermal energy storage (TES) which may soon allow 24 hour operations of solar plants as well as energy storage between the seasons with only small losses.
Battery storage has also got potential but still needs to demonstrate that it eventually can become cost-effective and reduce its significant ecological footprint. Clearing the energy storage bottleneck will be the key challenge for a full-blown switch to renewable energy societies and a robust commercial basis for energy producers, with no recourse to state subsidies.
Clearly there’s a long way to go before a zero-carbon energy supply can be achieved. People who say it can be done by 2025, 2030 or even 2050 don’t know what they’re talking about.