Energy storage technologies are evolving quickly, but there is still a long way to go before they can join with renewable energy sources to form a stand-alone solution to the world’s power needs.
Lithium-ion batteries have long been seen as the answer to overcoming the intermittency issues associated with renewables. Yet they are not without problems, both in terms of capacity and environmental impact.
There are other energy storage solutions, though, that don’t share these side-effects to the same extent. Here are four examples.
1. Flow batteries
When combined with renewables, batteries are a valuable way to store surplus energy that can be released when there is insufficient wind or sun to maintain electricity supply. But whereas lithium-ion batteries are difficult to deploy in the large sizes needed to provide backup power to towns or cities, flow batteries have fewer constraints.
Utilizing tanks of electrolytes, flow batteries have the capacity to store enough electricity to power thousands of homes for many hours, making them easier to scale up. A new generation of these batteries could soon provide back-up power to wind and solar installations on a grand scale.
Mitsubishi Hitachi Power Systems (MHPS) will provide the power equipment for what may become the world’s biggest energy storage project, located in Utah. The site will exploit the long lifecycles and higher power density of flow batteries.
As electricity replaces gasoline to power vehicles, the growing demand for electric vehicles (EVs) is creating new opportunities for energy storage.
EVs not only consume surplus electricity with each charge, they can also store it and feed power back into the grid to make up shortfalls during times of peak use.
Worldwide demand for EVs could reach up to 70 million vehicles by 2025, according to the IEA. As more charging infrastructure is put in place to service this booming demand – in places like shopping malls, office buildings and homes, as well as roadside refuelling stations – utility companies will be able to direct more power to where it is needed, with less waste.
Another way to use the surplus output from renewables is to power the electrolysis process needed to create hydrogen. This effectively makes hydrogen an alternative energy storage solution to batteries.
Using clean energy to produce alternative fuels like hydrogen can help cut carbon dioxide emissions without disrupting energy supplies.
MHPS has successfully tested a large-scale gas turbine capable of running on a 30% hydrogen fuel mix, for example. The hydrogen blend reduces carbon dioxide emissions by 10%, compared to a standard natural gas-fired plant.
4. Hybrid power
Smart, hybrid power solutions can bring baseload energy supply to remote parts of the planet, transforming communities with limited access to electricity.
Mitsubishi Heavy Industries Engine & Turbocharger (MHIET) has developed the triple-hybrid system, which combines solar power, battery storage, and a backup generator to supply round-the-clock power. The system can generate electricity in isolated places, such as remote villages in Africa, mining areas in Australia or island holiday resorts.
Solar panels harvest sustainable energy from the sun, but when sunlight is obscured a powerful battery provides temporary backup to stabilize supply and boost it during peak demand. Overnight, the generator’s engine powers the system until the sun comes up, when clean solar energy backed up by battery power replaces the engine, which is switched off.
This is all run by a control system, which coordinates all three elements to even out supply and maximize clean energy use and storage.