Big batteries offer reliable, green power

Tesla's "big battery" utility-scale Powerpack systems are emerging around the globe, proving a supplemental energy storage system that reduces costs and provides a reliable backup in cases of emergency.

The Hornsdale Power Reserve in South Australia, owned by French renewable energy producer Neoen, is currently home to the largest lithium-ion battery energy storage system in the world with 100 megawatts (MW) of power storage and 129 megawatt-hours (MWh) of output capacity.

This power reserve saved consumers US$75.78 million in power costs during 2019, which is a 290% increase over the US$26.14 million savings during 2018.

With nearly triple the savings to consumers from the previous year, the Tesla Powerpack at Hornsdale has played a significant role in grid stability, a function previously dominated by fossil fuel generators which would bring energy prices high during system faults or planned maintenance.

The success of Tesla's big battery has been so obvious that Neoen contacted Tesla to expand the already incredible size of the system by 50 percent, to a 150MW facility.

Australian power reserve operators decided to expand in a bid to stabilize the nation's fragile electricity grid with the Australian government pledging up to US$15 million in grants to support the development.

While there are several other big battery projects being planned in Australia, including a massive 900MW project proposed by Neoen in South Australia that would connect wind and solar farms, similar infrastructure is underway in several other places around the world.

Frequency control

In addition to storing non-carbon-emitting wind and solar energy, the big battery projects in Australia and around the world help to provide grid reliability.

When a power plant goes down or when there is greater demand for energy, it is practically a race to meet that demand. A battery auxiliary power system beats power providers dependent on fossil fuel and gives consumers a win-win scenario. Consumers benefit from lower prices and low downtime during blackouts that can disrupt businesses or daily household activities.

It is during these moments of instability that fluctuate the costs for the consumer. In power systems, when the load is more than the supplying power, the frequency in the system will drop. Correspondingly, when the load is lower than the supplying power, the frequency in the system will increase.

Load disturbance is a common problem, and this cannot be controlled as the load demand is based on consumer use. Therefore, to operate the system in a stable condition, it is required to be continuously monitored and controlled over the frequency at the generating stations.

A report by Australian consulting firm Aurecon analyzed the impact of the Tesla big battery at Hornsdale Power Reserve in its role in the frequency control and ancillary services (FCAS) markets. These are basically events that require quick reactions when there are sudden changes in demand or supply.

According to Aurecon, the biggest savings came from the raised FCAS and amounted to more than US$32.65 million.

Tesla's big battery has demonstrated how lithium-ion battery power reserves can play a big role in the security of the overall grid. While fossil fuel powered generators would ordinarily take several minutes to feed power to the grid in need, the fast-discharge capability of the battery can nearly instantaneously deliver affordable energy to consumers access.

This also bodes well for owner and operator Neoen to make most of the potential returns, and of course, for Tesla's energy business.

The immediate power that is provided by Tesla's big battery backup allows for much smaller margins of energy consumption and fractionally small downtime during periods of instability which in turn reduces costs for consumer and provider alike.

The race for the biggest battery

With lithium-ion battery prices falling 76% since 2012 and 35% in 2019 alone, energy storage is becoming an increasingly cost-competitive option to pair with large-scale solar, in a growing number of locations.

Last March, Hawaii regulators approved their 247MW/988MWh of solar storage projects across the islands that make up the state.

At about the same time, Florida Power and Light announced that it will deploy a 409 MW/900 MWh battery at the existing solar plant in Manatee County.

FPL estimates that the Manatee project will be four times as large as the biggest battery currently online. It also has a larger capacity – though not a higher energy rating – than Dynegy's 300MW battery project in Monterey County, which California regulators approved in 2018.

Currently the "world's biggest battery" is an ongoing contest, and there are other contenders besides Australia's Hornsdale and Florida's Manatee projects.

Buried in the hundreds of projects in the interconnection queue of Texas' grid operator are the Juno Solar and Juno Storage projects, 495 MW of solar and 495 MW of batteries that Intersect Power is planning to develop in West Texas' Borden County.

The Juno projects already have interconnection agreements, and together are easily the largest solar storage project seen to date. However, the project is not expected to begin until May 2021, and in the coming years it is likely that even larger batteries will be announced.

California company Pacific Gas and Electric has invested heavily into Tesla's massive project to deploy 1 gigawatt-hour (GWh), equivalent to 1,000 MWh, with their battery packs to create a giant energy storage system. This system would involve four storage projects with two of them in the running for the world's biggest batteries.

In 2018, Tesla's proposal for the project showed that the company plans to use a "Megapack" instead of its usual Powerpack for large utility-scale projects.

Tesla's Megapack can have an energy capacity of up to 3MWh, and according to Tesla's plan, they will deploy 449 Megapacks at the site of the PG&E grid.

Tesla is listing the project as having a total capacity of 1.2 GWh, which would mean that each Megapack has a capacity of 2,673kWh. That's more than 12 times the capacity of Powerpack 2 in a package that could potentially fit about eight Powerpacks.

The total capacity of those 449 Megapacks represents more energy capacity than Tesla Energy deployed throughout its first three years of operation – all Powerpacks and Powerwalls combined.

The shift to a cleaner and more stable energy storage system is quickly becoming reality and the options for that shift are widening as well.

With the technology, demand and benefits laid out easily before energy utility providers, it won't be long until we see a complete swing in favor of renewable energy and the storage of that energy perhaps being the most vital.