Demand for reliable, renewable energy in homes is at an all-time high. Michael Nelson looks at the innovation being made with traditional lead acid batteries, and their future application in sustainable power storage.
Lithium-ion batteries have been one of the most crucial developments in forming our modern world, used in many 21st century electronic products including mobile phones and laptops, and supplying energy to medical equipment and power tools. While Lithium-ion batteries are also being used in green technology, innovation in traditional lead acid batteries means that they too are paving the way to a sustainable future.
Formally known as the Advanced Lead Acid Battery Consortium, the Consortium for Battery Innovation (CBI) are a non-profit global research organisation within the lead acid battery industry, comprising of about 110-member companies, from battery manufacturers, suppliers and end users to universities and laboratories.
They act as a voice for the industry, talking about innovation and representing the technology across standards and testing sequences. However, their focus is as a research organisation for lead acid batteries.
Dr Matt Raiford, technical manager at CBI, says that while every battery chemistry will have to be utilised to meet sustainable energy storage targets, traditional lead acid batteries offer several key advantages over other solutions.
“The infrastructure to support the use of lead acid batteries is already there to meet the demand, particularly in the Western hemisphere where there’s a strong manufacturing industry for them.
“We’re also continuing to see performance improvements across the 12-volt automotive, telecommunications and energy storage sectors based around the innovations made regarding the use of lead in batteries.”
In terms of safety, lead acid batteries are also superior because they are much less likely to spontaneously combust compared to other chemicals used in batteries. This is because lead is relatively inert in the presence of air, and they use a water-based electrolyte, whereas lithium, for example, uses organic electrolytes and is energetic in the presence of air.
One of the biggest advantages of lead acid batteries, however, is the rate at which they are recycled. According to the International Lead Association, the collection and recycling rates of lead batteries exceeds 95 per cent in most regions of the world.
“In Europe and North America, the effective recycling rate is 99 per cent,” says Raiford. “This means there is unparalleled sustainability in the lead acid battery industry, resulting in something that is especially useful in terms of how society uses it right now. We believe that is really important as the world moves towards decarbonisation and electrification.”
Bipolar lead acid batteries used in residential energy storage
In collaboration with CBI, engineers from Gridtential Energy and Electric Applications Incorporated (EAI) are working together to develop quick and safe ‘plug and play’ solar powered energy storage systems to meet the demand for secure, renewable energy for home use.
Currently, lithium batteries are managed at a high amount of detail, down to each individual cell, which means a lot of control mechanisms and complicated algorithms are used to manage this.
In the case of lead battery technology, it can be done at a level where it is possible to control a connected series of batteries all at once. This means that there is a more straight forward control scheme involved, and it is easier to make and install.
“That is kind of what the term plug and play means,” says Raiford. “The goal of the project is to produce something that works well, but that’s also easy for the consumer to put in their house, which is a key driver.”
To achieve this, Gridtential’s Silicon Joule technology would be used in constructing a high-voltage battery designed specifically for behind-the-meter (BTM) energy storage applications. This lead acid battery uses silicon wafers like those in solar cells to reduce weight and achieve performance competitive with lithium-ion batteries at a lower cost.
“If you look at a typical battery, everything is lined up and all the connections are through the top,” says Raiford. “If you were to look inside, you would see that the energy is flowing from the top contacts down to the bottom of each component, and vice versa, as you discharge.
“What is interesting about Gridtential’s bipolar battery technology is that it transmits energy through the thickness of the plate, so the entire electrode is being used uniformly, providing much higher energy density and a longer battery lifecycle.
“These are the kinds of things that are important for residential application, because you want smaller, safe systems that are easy to connect.”
BTM energy storage such as this is a critical piece of the decarbonisation landscape. In the U.S. alone, energy consultancy company Wood Mackenzie predicted that 430 megawatts (MW) of BTM energy storage systems would be installed in 2020, an increase of more than 100 per cent over 2019.
“Integrated PV-battery backup systems are a fantastic application for Silicon Joule technology due to its superior cycle life, low cost, safety and recyclability; all of which are of utmost importance to residential consumers and small business owners, and set this technology apart from other batteries,” John Barton, CEO of Gridtential says.
Increasing the lead acid battery life cycle
Another of CBI’s high priority research projects is focused on increasing the battery cycle life by five times by 2022. They have seen huge progress in the two and a half years since this project began, both through their programme and through individual companies’ own development.
“One of the things we have learned,” Raiford adds, “is that end users really want to get their hands on batteries and do the testing themselves, regardless of the technology. Whether it be lead, lithium, sodium, or zinc, they want to develop their own internal view of technology.
“We’ve been doing testing at Pacific Northwest Laboratory, National Renewable Energy Laboratory, as well as institutions in Europe, to gather third party data on battery cycle life, and we’re seeing that the way lead batteries are being handled in their lifetime have improved dramatically.
“It’s very common now to see lead batteries that have 3000 cycles at very high depths of discharge, and that’s a big difference compared to five years ago.”
This is not to say that there are no obstacles when considering the life cycle of batteries. Lead batteries perform well at a partial state of charge, especially bipolar battery platforms. However, the ability to use lead acid batteries in residential or energy storage applications, for example, is ill-defined at this stage. That is why the results of testing will be crucial.
“Part of the testing regime will be trying to get it to work in the way that it is supposed to. There will be some simulations where the battery will be plugged in to a known load, as well as generation simulations on micro-grids.”
Despite the challenges ahead, Raiford is confident that innovations in lead acid battery technology, and its high levels of recyclability, means it will continue to be a major contributor to energy solutions going forward.
“We see sustainability being especially important. Things like supply chain and the criticality of minerals are concerns for all federal governments, and the fact that lead batteries are so highly recycled and are well-known, with good infrastructure, is a big positive.”