There are pros and cons associated with the two main battery chemistries used in solar + storage projects. Lead-acid batteries have been around much longer and are more easily understood but have limits to their storage capacity. Lithium-ion batteries have longer cycle lives and are lighter in weight but inherently more expensive.

There are pros and cons associated with the two main battery chemistries used in solar + storage projects. Lead-acid batteries have been around much longer and are more easily understood but have limits to their storage capacity. Lithium-ion batteries have longer cycle lives and are lighter in weight but inherently more expensive.

Can one combine the pros of each chemistry to make one cost-effective, high-capacity battery bank?

Does one have to dismantle their lead-acid battery bank just to tap into the functions of a new lithium-ion battery? Can one add a few cheaper lead-acid batteries to their lithium system to meet a certain kilowatt-hour capacity?

All important questions with a less defined answer: it depends. It is easier and less risky to stick with one chemistry, but there are some workarounds.

Gordon Gunn, electrical engineer at Freedom Solar Power in Texas, said it is likely possible to connect lead-acid and lithium batteries together, but only through AC coupling.

“You absolutely cannot connect lead-acid and lithium batteries on the same DC bus,” he said. “At best, it would ruin the batteries, and at worst…fire? Explosion? A rending of the space-time continuum? I don’t know.”

K. Fred Wehmeyer, senior VP of engineering at lead-acid battery company U.S. Battery Manufacturing Co., provided further explanation.

The market for grid-connected energy storage will defy the “headwinds” caused by the coronavirus pandemic on industries across the world, analysis firm IHS Markit has predicted.

The team at the IHS Markit Energy Storage Service has forecast that global installations will grow by over 5GW this year, despite disruption caused by COVID-19. Battery energy storage is becoming increasingly able to competitively provide critical capacity to energy networks, the analysts said, particularly in the US, which is currently the world’s biggest market for grid battery storage.

After what was a relatively low level of installations in 2019 of 2.7GW, the rebound that began with a strong first quarter of 2020 will continue on, IHS Markit believes, with annual installations set to rise fivefold between 2019 and 2025.

While installation figures could reach 15.1GW / 47.8GWh, hardware revenues will increase from US$4.2 billion this year to US$9.5 billion in 2025. At the same time, battery module prices are expected to fall around 32% in those years.

“The increasing competitiveness and critical role of battery energy storage assets in supporting the decarbonisation and resilience of the electricity system means that opportunities for energy storage continue to develop despite the turmoil caused by the COVID-19 pandemic,” IHS Markit Energy Storage Service research manager Julian Jansen said.

Engineering professors and students at the University of California – Riverside have demonstrated a method they hope could “solve two of Earth’s biggest problems in one stroke” – recycling plastic waste such as plastic bottles into a nanomaterial useable in batteries.

As battery storage becomes an ever more present necessity – used in large-scale energy storage projects through to electric vehicles – sourcing materials traditionally necessary to make batteries are straining, and more sustainable alternatives are necessary.

Two engineering professors at the University of California Riverside, Mihri and Cengiz Ozkan, have been working with their students to create improved energy storage materials from a range of sources, trying everything from glass bottles to beach sand, Silly Putty to portabello mushrooms.

Their latest effort, however, has the ground-breaking potential to address not only the need for sustainable battery materials but also the need to recycle and eliminate tonnes of plastic waste.

“Thirty percent of the global car fleet is expected to be electric by 2040, and high cost of raw battery materials is a challenge,” said Mihri Ozkan, a professor of electrical engineering in UCR’s Marlan and Rosemary Bourns College of Engineering.

“Using waste from landfill and upcycling plastic bottles could lower the total cost of batteries while making the battery production sustainable on top of eliminating plastic pollution worldwide.”

“Resilience” is a powerful word in 2020. Fires, floods, pestilence, pandemic — I don’t know about you all, but I was raised in a fundamentalist Southern Baptist Church and my Revelations bingo card is just about full.

Thinking about the idea of resilience as it relates to equity and energy systems merely as the ability to keep the lights on, however, is missing a powerful opportunity to right the scales of justice. Large corporate energy buyers and utilities, in particular, hold the opportunity to build better and make things right.

On resilience
The term “resilience” can be applied to a vast array of natural, built and social systems and refers to the ability to recover function following a significant, potentially unpredictable disruption. As it relates to energy, moving away from long transmission lines and centralized power plants burning extracted, polluting fuels and towards a distributed system that combines local energy storage with renewables improves resilience — consistent with the principles of biomimicry. That’s the vision.

But how is that vision valued? Resilient energy systems combining renewables, microgrids and energy storage are being deployed by corporations and other institutions that can assign an economic value to resilience as a service, by residential customers who can afford it and by utilities that benefit from the resulting infrastructure and other cost reductions.

If we define the value of resilience in such narrow economic terms, however, we will build a clean energy dystopia. But we can choose a better way.

Do justice
Our energy systems, like most legacy systems, are infused with racial injustices that do particular harm to Black communities, families and individuals because many of our laws and institutions were designed for that purpose.

Qatar General Electricity and Water Corporation (Kahramaa), has commissioned the Middle Eastern country’s first ever megawatt-scale battery storage system in time to measure the pilot project’s effectiveness at dealing with peak demand in summer.

The state-owned electricity and water company announced last week that the deployment and grid connection of a 1MW / 4MWh Tesla Powerpack battery energy storage system (BESS) had been completed “ahead of schedule and beginning operations to benefit from it during the summer period,” during which Qatar’s energy demand is at its seasonal highest.

This was despite “many challenges” that a team of “young Qatari personnel” had to overcome during the project’s execution, Kahramaa said, particularly around managing and training workers during the COVID-19 pandemic.

The pilot project could prove to be important in the Gulf State if successful, with the electricity and water supplier and regulator investigating whether the technology and its applications could be scaled up to be used at high-load substations in the country’s electricity network, and could also be integrated with large-scale renewable energy projects including the 800MW solar PV project Al Kharsaah near Qatar’s capital Doha which was tendered for and got a then-record low-price tariff in January.

The past month has been littered with news of exceptionally large battery storage developments, yet none in the world can compare to the news that Vistra’s permit to expand an energy storage system under construction at its natural gas-fired Moss Landing generation station to 1,500 MW/6,000 MWh has been approved.

That’s right. Gigawatt-scale battery energy storage is on the table.

The proposed expansion would quadruple the battery system’s size and make it the largest battery storage installation in the world, a couple of times over.

While the permit has been approved, the expansion will happen “should market and economic conditions support it,” according to Vistra President and CEO Curtis Morgan.

For some perspective as to how large this battery is, consider that, according to the U.S. Energy Information Administration, the country’s entire installed battery storage capacity at the end of 2018 came in at 869 MW, while total installed battery storage at the end of 2019 (including behind-the-meter) was approximately 1.7 GW, according to Wood Mackenzie. This one battery, when completed, will be larger in capacity than every other utility-scale battery energy storage system in the country, combined.

The system is coming in stages, only two of which have been formally announced. The first 300-MW phase is planned for completion by the end of 2020, with the second, a 100-MW expansion expected to come a year later in 2021.

Global perspective

This system is not the only gargantuan battery going in at the Moss Landing site. Set to clock in at 182.5 MW and 730 MWh, the Moss Landing battery energy storage system will be comprised of 256 Tesla Megapack battery units on 33 concrete slabs at the substation. The project’s targeted completion and energization is set for early-2021, with the project achieving full commercial operation in Q2 2021.

The more variable renewable energy there is in the grid, the higher the value of utility-scale storage systems. Researchers from the Massachusetts Institute of Technology (MIT) have used a high temporal resolution capacity expansion model called GenX to determine the least-cost approach to deploying large-scale storage into a low-carbon power system.

Lead-author and research scientist at the MIT Energy Initiative, Dharik Mallapragada, and his colleagues published their results in the journal article, Long-run system value of battery energy storage in future grids with increasing wind and solar generation, which appeared in the academic periodical Applied Energy.

In this research, the team attempted to identify the various sources of value generation that a storage system can tap into and the respective economic dynamics connected to these value sources. The most significant source of value for battery storage assets is the subsequent capacity deferral. Where a grid operator installs battery storage capacity, expensive transmission line capacity or natural gas plants can be avoided.

“Battery storage helps make better use of electricity system assets, including wind and solar farms, natural gas power plants and transmission lines, and that can defer or eliminate unnecessary investment in these capital-intensive assets,” says Mallapragada. “Our paper demonstrates that this capacity deferral, or substitution of batteries for generation or transmission capacity, is the primary source of storage value.”

To come to this conclusion, the researchers analyzed the holistic system value of energy storage. Specifically, the team looked at two variants of abstract power systems in the U.S.’ Northeast and Texas regions. To this end, information on load profiles and generation data for variable renewable energy was consistent with real-world figures.

We are in the middle of the most remarkable transformation in the history of the electricity grid — from dirty and centralized to clean, distributed, and digital. Many policymakers and pundits believe that if only we had enough batteries, we could adapt to this new mix of generation resources and continue to pretend that nothing but a few operating conventions have changed.

And indeed, utilities, regulators and state legislators are allocating ever-larger piles of ratepayer and taxpayer money to subsidize lithium-ion batteries on both sides of the meter. Subsidizing batteries sounds simple and wonderful, but the unspoken problem is that the emperor has no clothes. There is no economic model of behind-the-meter batteries for grid purposes — period.

Don’t get me wrong: I love batteries. I drive a battery to work every day. I’ve checked the math behind utility-scale batteries combined with renewables as a substitute for gas peakers, and in many places, it checks out. I even understand the attraction of batteries in microgrid or resilience projects, as a clean but expensive alternative to generators.

But as an energy economist and former utility rate designer, I am cursed with the ability to do basic arithmetic, so to be clear: The economics of behind-the-meter (BTM) batteries in grid-connected commercial buildings are and will continue to be wasteful, inefficient and impractical, to put it kindly.

I know, I know. You’re saying, “But lithium-ion batteries are really cheap, and they keep getting cheaper, and that changes everything!”

Except that it doesn’t. I read the same reports as you do, but those $150-headed-toward-$100/kWh numbers for battery capacity prices have nothing to do with the installed cost of a battery in a commercial facility. We are not making master electricians any cheaper, nor permitting any easier, nor fire suppression any less necessary, nor commercial floor space any more widely available.

In our experience with real-world small to medium commercial solar buildings, the actual all-in installed cost of BTM batteries is about $1,000/kWh — or more. That means that even if the price of lithium-ion batteries at the factory gate reaches $0/kWh (not a typo), the installed price will still exceed $850/kWh. That is cost-prohibitive in grid-connected commercial buildings everywhere.

Tesla TSLA +5.2% and PG&E recently broke ground on a record-setting energy storage system in Moss Landing (Monterey) California that, once complete, will be the largest such installation in the world. The battery park will be able to dispatch up to 730 megawatt hours (MWh) of energy to the electrical grid at a maximum rate of 182.5 MW for up to four hours using 256 of Tesla’s lithium-ion (Li-ion) Megapacks. Tesla and PG&E will have the option to upgrade Moss Landing’s capacity to bring the system up to 1.2-gigawatt-hours which could, according to Tesla, power every home in San Francisco for six hours.

The facility is expected to come online in 2021 and will be designed, constructed, and maintained by both companies, with PG&E retaining ownership. The construction of the Moss Landing site and other such mega-storage projects around the world portends a massive shift away from hydrocarbon-based power systems towards renewable generation backed up by utility-scale storage. According to Fong Wan, a senior vice president at PG&E:

“Battery energy storage plays an integral role in enhancing overall electric grid efficiency and reliability, integrating renewable resources while reducing reliance on fossil fuel generation. It can serve as an alternative to more expensive, traditional wires solutions, resulting in lower overall costs for our customers…the scale, purpose and flexibility of the Moss Landing Megapack system make it a landmark in the development and deployment of utility-scale batteries”

If the Moss Landin site is upgraded to the 1.2 GW capacity as anticipated, its storage capacity will be approximately ten times larger than Australia’s Hornsdale Power station, the previous record holder and another Tesla project. The next largest Li-ion storage system in the world is the United Kingdom’s Stocking Pelham station at 50 MW.

The construction of the battery farm in Moss Landing promises improved flexibility for grid demand spikes and load smoothing for variable generation from renewables. PG&E predicts that the Tesla Megapack system will save consumers more than $100 million over the project’s 20-year life span when compared to the forecasted local capacity requirements and procurement costs necessary in absence of the facility.