Which batteries are best suited to grid management and renewable energy storage?
Many industry experts agree that batteries have the capability to transform the way we manage our energy in several key areas:
- Drawing power from the grid and storing it to use at more expensive peak times
- The ability to shift power from renewables
- Providing power to the grid to earn additional revenue
- Protecting businesses through a reliable backup supply
There are numerous developing technologies in the battery industry. We take a look at three popular choices for energy storage, grid management and power shifting from renewables.
Batteries are certainly not a new technology and lead acid, the traditional go-to batteries for back up UPS (uninterrupted power supply) and large equipment, has been around for over 100 years.
Lead acid batteries are an economical choice. They cost roughly half as much as lithium-ion but their charging time and cycle life makes them less suited to grid services and renewable energy solutions. New deep-cycle lead acid batteries have increased the performance and energy output making them a more viable low-cost battery choice for renewables.
The downside of lead acid batteries is their environmental impact; they require many more raw materials and energy intensive lead processing than other batteries. They also contain toxic components. Fortunately the systems are already in place to recycle lead acid batteries so they rarely end up in landfill.
Lithium-ion is the most common storage battery, often found in smart phones, tablets, power tools and electric vehicles. Lithium-ion is lighter than lead acid, with a lithium-ion battery weighing just one third of a lead acid battery. They can be wall-mounted and located indoors or outdoors.
A lithium-ion battery can harvest more energy as it discharges 94% versus 80% for lead acid. It is highly efficient in both charge and discharge, whilst lead acid batteries lose power when charging and experience reduced capacity due to voltage drops when discharging. Lithium-ion batteries also lose less capacity when idle and deliver more cycles over their lifetime than lead acid, making them ideal for providing grid services and coupling with renewable energy systems.
Lithium-ion batteries don’t require any maintenance or refills and can be recycled at the end of their life. The lithium-ion recycling industry is relatively new but the materials have demonstrated a high ability for recovery.
The biggest drawback of lithium-ion versus lead acid is their price, although we have already seen a significant fall in costs, which are expected to drop 50% in the next five years.
Flow batteries (VRFB)
Another emerging storage option is the vanadium redox flow battery (VRFB). The system uses integrated electronics to manage the charging and discharging process, which gives a low cost of ownership but increases the amount of infrastructure and therefore space required for the pumps, control units and sensors. On the other hand, it is easy to increase the capacity of an existing VFRB by simply adding more electrolyte when a lithium-ion system would require additional cells.
Developers of VFRBs say there are no cycling limitations and the recycled vanadium is not toxic and can be used repeatedly in other industries. Flow batteries are comprised an aqueous-based electrolyte that does not get hot and become a fire risk.
The VRFB batteries appear to be a promising choice for larger scale grid management services, although the market is not yet as developed as it is for lithium-ion.
Navigating the many options for battery storage can be a bit of a minefield and every technology has its pros and cons. The battery industry is continually advancing and whilst we may see an exciting new development in the near future this should not deter us from investing in the technologies that are already available today.
If you are looking to invest then it is a good idea to seek independent advice from an energy expert who can advise you on which type of technology is most suited to your individual requirements. It is also wise to choose a reputable manufacturer who can offer a lengthy warranty and recycling services on your new system.
Don’t forget that the software plays an equally important role, as it is essentially the brains behind your battery.