Kathy Gibson reports from the XON/NEC Summit – Traditional energy systems do not allow for the storage of excess energy – but grid storage does.

Using grid storage solutions, energy can come from multiple sources, and it can be stored to be used in a high-demand time.

But grid storage is not just about saving energy to use later: it can also make the power grid more reliable and resilient. And grid solutions that are containerised are easy to deploy where they are needed.

NEC’s Roger Lin points out that the electricity grId is undergoing transformation as new sources of energy are being tapped, and usage patterns change.

“But there are huge challenges to this,” he says. “Currently, the grid is built to accommodate peaks. But what if there was a way to make better use of the infrastructure? There is technology that can help the grid to be more efficient and better utilised.”

NEC supplies a containerised grid storage solution that is currently deployed in about 200 installations around the world, with about 600MW of power under management.

The system can be used by power utilities to supplement or regularise their power supply, but it can also be used by electricity users to make sure they don’t suffer interruptions.

NEC’s Adam Briggs says that the growth in the system is expected to come from customer-side connections. “In a place like South Africa, you will see companies and in some cases residents taking control of the grid and reliability themselves. It’s an opportunity to distribute the reliability.”

The specific opportunities to deploy grid storage in Africa include:

  • Help the utility gain reliability, delivering primary reserve support, which is being done in Chile.
  • Behind the meter applications for commercial and industrial support, providing reliability to customers that the grid currently doesn’t provide.
  • Solar and wind integration, which is relevant in emerging countries where the power utility finds it hard to keep up to date.
  • Micro-grids, for off-grid opportunities where a combination of renewable, generator and battery systems can create 24/7 power availability.

Lin adds that the company expects to be shipping grid storage for about 2GW by 2020, with a major push into emerging markets that don’t necessarily have reliable electricity systems.

The containers store power in banks of batteries which can take over the supply when the grid is interrupted or down. Briggs says that batteries are very efficient at taking energy in and out. “Relative to providing spinning reserve from diesel generators, batteries are probably more efficient as they store without any losses,” he says.

“Seeing a lot of opportunity for batteries to eliminate the need to run diesel generators.”

Most of the batteries currently in use are lithium ion, for both long duration and hybrid workloads. New storage technologies are also being tested that will support longer duration applications.

Lead acid batteries can be used, although they are not as durable as lithium-ion; and sodium sulphur batteries could be specified for particular applications.

Flow batteries are a new technology that could become mainstream in the near future, says Lin. These batteries offer opportunities for much lower-cost storage, although it currently has some issues around durability. “Flow batteries still have some challenges, we are working with the vendors to iron those out.”