New energy storage technologies are entering the market as business leaders and policy makers seek to address climate change, support renewable energies, and create a more reliable and resilient grid. But not all energy storage solutions are created equal. In addition to climate change, the global economy is facing several challenges. To promote long-term sustainability on a holistic basis, energy storage should support reliability and safety while benefiting people and the planet, including historically disadvantaged communities.
Why energy storage is important
The technology behind wind turbines and solar panels is more efficient and economically competitive today than ever before, but nothing can change the fundamental nature of wind and solar energy.
The wind speeds vary depending on the hour, day and season. Sunlight is absent all night, and cloudy weather can affect solar panel performance during the day.
This is where energy storage comes into play. Batteries can store enough electricity to fill in the gaps when the performance of wind turbines and solar panels dwindles.
Companies can use energy storage to absorb excess wind or solar energy in times of low demand and to discharge it strategically in order to avoid peak loads. You can also use energy storage instead of diesel or gas generators for the emergency power supply and avoid longer failures with solar-plus storage microgrids.
At a broader level of planning, large-scale energy storage can be deployed to avoid costly new transmission infrastructures and peak power plants, thus supporting economic growth and better health outcomes in remote or underserved areas.
In addition to the bottom line benefits, energy storage improves a company’s reputation. Many companies already step in with supplies and resources when emergencies arise in their area. On-site energy storage could allow them to include electricity on the list without the noise and pollution associated with fossil-fuel emergency power generators.
Beyond lithium-ion batteries
Lithium-ion is the most common energy storage technology today. Once limited to cell phones, laptops, and other portable rechargeable devices, lithium-ion batteries are now the technology of choice for most electric vehicle manufacturers.
In addition, there is growing interest in expanding the use of lithium-ion batteries for storing electricity for use on site in buildings and industrial plants, as well as for storing and feeding electricity back into the power grid.
However, there is a crucial shortcoming here. Lithium-ion batteries only last a few hours. This may be sufficient, especially in combination with smart grid technology. In other cases, however, the four-hour limit typical for conventional lithium-ion technology does not go far enough. In order to achieve a strongly decarbonised power grid that is resilient, reliable and stable, batteries with a longer lifespan and a running time of 10 hours or more are required.
In the field of energy storage, water comes first. Despite the rapid growth in lithium-ion batteries, pumped storage power plants still account for 97 percent of the large energy storage systems in the USA.According to the US Energy Information Administration (EIA), the average hydropower plant stores around 500 megawatts of emission-free electricity for six to 20 hours, safely and securely without fear of fire, toxic chemicals, or end-of-life hazardous waste problems.
However, it is not expected that hydropower will be a large part of the energy storage solution in the future. The water resources required for hydropower plants are geographically limited and the provision time is many years. New project development is further constrained by wildlife and habitat protection concerns and competing interests such as river transportation, fishing, recreation, and Native American rights. So the need for a breakthrough is clear.
In addition, the US Department of Energy, grid planners and other stakeholders agree that the future grid will no longer be so dependent on large, centralized power plants that run on water or fossil fuels.
Instead, decentralized energy resources, including rooftop solar panels and small wind turbines, will play a more important role. In order to adapt to the power grid of the future, long-term energy storage systems must be so scalable and flexible that they can be placed almost anywhere.
The search for sustainable long-term energy storage
Long-term energy storage is a key feature of the Department of Energy’s plans to add more wind and solar power to the grid without sacrificing reliability and stability. The Ministry of Energy has recognized the four-hour limit for conventional lithium-ion technology and defines long-term energy storage as a device or system that can generate electricity for at least 10 hours, preferably for several days with a duration of 100 hours or more .
The recently passed Senate Infrastructure Act supports the Department of Energy’s efforts in this area by providing billions in funding for long-term energy storage projects and domestic supply chain programs.
It is possible to connect sets of lithium-ion battery arrays in a sequence that lasts longer than four hours. However, the cost of such a system is often prohibitive, especially when the goal is to keep the power supply going for several days.
In addition, the environmental and social effects of over-reliance on lithium technology are gradually becoming apparent, and the picture is not pretty.
While the US has large reserves of lithium to be mined, fossil fuel advocates are among those suggesting that the local environmental impact of lithium extraction and refining shares characteristics with the impact of coal, oil, and gas operations.
In addition to its environmental and public health effects, lithium mining can raise significant social, cultural and human rights problems. In the US, most of the lithium reserves are concentrated in western states, where the once dormant domestic lithium mining industry has become a hotbed for activity that is creating new concerns about water resources and the use of public land.
Native Americans in Nevada, for example, have partnered with ranchers and conservationists to fend off at least one new lithium mine that was approved on state during the Trump administration. The impact of lithium mining on indigenous communities in other countries has also caught media attention.
Researchers are working on lithium recovery methods that reduce surface degradation and eliminate the need for large evaporation basins. However, the use of toxic substances in the refining process is a problem that has yet to be resolved and the disposal of large amounts of brine could pose problems similar to the infamous problem of fracking waste disposal.
The exploding demand for lithium shows no signs of slowing as the growing number of stationary battery arrays compete with myriad electronic devices for raw material resources. With millions of EVs rolling off the assembly line in the near future, both delivery and end-of-life problems appear to be on the increase.
More options for sustainable energy storage
A growing number of more sustainable options for long-term energy storage are emerging. One approach uses heavy blocks to replace hydro and hydropower turbines. When renewable energy is available, electric motors lift the blocks to the top of a tower. When more electricity is needed, gravity takes over. The blocks are allowed to gradually fall back down and generate electricity in the process.
The blocks themselves can be made from any material with optimal dimensions. This opens the door to new opportunities for recycling wind turbine blades and other materials that support the transition to renewable energies.
Such recycling would represent a decisive advantage over lithium-ion technology. Although lithium-ion batteries can be recycled, there are few recycling facilities today that are large enough to hold the amounts of waste batteries that will populate the world in a few years. And while the global lithium recycling industry can expand, doing so would have additional environmental impacts related to transportation emissions and facility operations. It would also burden the supervision of illegal recycling processes, which is already heavily burdened by the global plastics crisis.
In terms of lifecycle sustainability, gravity-based energy storage is better suited for the circular economy of the future. However, its application is restricted to locations with sufficient space and, due to the height of the towers, is subject to zone-specific restrictions, competing uses and aesthetic considerations.
Location constraints also come into play for other long-term energy storage technologies that are developing in the pilot and demonstration stages, such as compressed air systems.
In terms of a sustainable solution that is suitable for almost every application, what is really needed is some kind of hydropower dam in a box – i.e. a relatively compact system that uses little or no toxic chemicals, maximizes compatibility with the circular economy, and does so for 10 hours or more Store and deliver electricity.
Flow batteries are one such option. As the name suggests, flow batteries use two types of specially treated electrolytes to generate and store electricity. The electrical charge is created when the electrolyte, pumped by electricity from the grid or a paired generator, flows across a membrane. When ions cross the membrane in one direction, the battery charges; if they cross in the other, the battery discharges.
Researchers have perfected flow batteries since the science was first confirmed in the 1970s. It is only in the past few years that flow batteries have finally begun to bridge the gap that separates promising laboratory technologies from successful commercial use. And today the decades-long promise of long-lasting, low-impact and cost-effective energy storage with flow batteries is finally here.
Headquartered near Portland, Oregon, ESS Inc. has been working on river batteries for a decade and is now poised to shake up the storage sector. Founded in 2011, ESS received a grant from the Department of Energy a year later for its flow battery design, which met the agency’s high standards for both cost and efficiency.
This initial investment and the subsequent further financing have paid off. After years of development, the company has created a safe, reliable new flow battery that is durable and sustainable, as well as cost and efficient, with an electrolyte that uses underground iron, salt and water to generate and store electricity.
In the coming months, in partnership with ESS, we will take a closer look at emerging energy storage solutions in general – and flow batteries in particular – and their role in a clean energy future. You can follow the series here.
This series of articles is sponsored by ESS, Inc. and produced by the TriplePundit editorial team.
Image courtesy of ESS, Inc.