Many environmentalists dream about an energy future that fully relies on solar and wind power, where batteries provide power during periods without sufficient sun or wind. However, battery storage radically increases the cost of providing electricity to end users, and battery manufacturing results in serious environmental impacts that must be considered. The availability of raw materials to manufacture the batteries must also be considered, as must the degree to which mineral availability could affect geopolitics. Finally, any plan to power the grid in the future with batteries must consider our capacity to manufacture batteries at scale.
Cost
MIT technology review estimates that it would cost $2.5 trillion to build a battery storage system to meet 80 percent of US electricity demand with solar and wind power[1]. There is reason to believe that this estimate is unrealistically low, because the price of the raw materials used to make the batteries would increase considerably if someone were to purchase such a large quantity of batteries. But consider that even the $2.5 trillion is more than three times what it would cost to build all new combined cycle natural gas plants for the entire US ($740 billion)[2], and the $2.5 trillion does not include the cost of power generation. Two other salient facts will help to understand battery costs[3]:
- To store energy in grid-scale batteries is about 200 times more than the cost to store natural gas to generate electricity when it’s needed; and
- While a barrel of oil can be stored in a $20 tank, the cost to store an equivalent amount of energy in Tesla batteries is $200,000, which collectively weigh over 20,000 pounds.
Perhaps the most daunting part of the battery cost analysis is the observation that grid-scale batteries do not usually last longer than 11 years (and sometimes much less)[4]. This means that the electric utilities in the U.S. would incur the $2.5 trillion-dollar cost every decade or so.
Environmental Impact
The raw ingredients for batteries must be mined, and mining is one of the industries whose environmental impacts were so obvious and significant that they birthed the environmental movement. Typical batteries for grid-scale systems use lithium, copper, nickel, graphite, rare earth metals, and cobalt. I have personally seen and inspected dozens of mines for EPA, and I can tell you that making policy choices to increase our reliance on these operations will increase man’s impact on the environment.
Taking copper for example to illustrate the point, the U.S. extracts copper mostly from southwestern states using large, open pit mines (see photo below for example). These pits are excavated using heavy earth-moving equipment powered by fossil fuels. Once the unconsolidated soil – called overburden – is removed, the rock must generally be blasted prior to excavation using ANFO, a mixture of ammonium nitrate fertilizer and fuel oil (basically diesel)[5]. The rock that does not contain enough copper to justify the expense of processing – called “waste” or “development” rock – is hauled outside of the mining pit and placed in enormous piles out of the way of the mining activities. The rock containing sufficient copper – called “ore” – is ground up and processed via hydro- or pyrometallurgical methods. Hydrometallurgical processes will leach copper out of the ore by spraying sulfuric acid over the massive piles with enormous sprinklers. The copper bearing acid is then processed into copper cathode using solvent extraction (with kerosene and other chemicals) and electrowinning (basically using large quantities of electricity to plate the copper out via electrolysis). Pyrometallurgical processes generally concentrate the ore using petroleum-based chemicals to “float” the copper out of solution and then roasting and smelting the concentrate to oxidize the copper. From there, the smelted copper undergoes further hydrometallurgical processing.
Source: https://toursofutah.com/blog/kennecott-copper-mine-things-to-do-in-salt-lake-city/
Mining companies discharge the rock material and excess liquid that has been separated from the concentrate into massive tailings dams. These tailings would technically be considered hazardous wastes based on their toxic constituents in many cases, were it not for the Bevill Exclusion. This piece of legislation exempts the mining industry from environmental regulations which would make mining unprofitable in the U.S. Whole books could be written on the impacts of the various parts of the copper mining process, but here is a quick summary of the main impacts:
- Massive open pits and tailings dams, which are often too toxic for plants to grow on them. Many of these are reclaimed by covering with impermeable clay caps, topsoil and vegetation, but mining companies frequently go bankrupt before this happens.
- Fossil fuel usage and resulting emissions from heavy earth moving.
- Groundwater contamination from tailings dams and acid rock drainage. Sulfide compounds common in copper deposits acidify the rainwater that falls on the mining areas and stockpiles (including waste rock), and the acidity dissolves metals in the rocks, causing them to run off into the environment.
- Sulfuric acid drift from leaching operations.
- Significant emissions from roasting and smelting of copper ores.
In general terms, these processes are similar to those for mining the other minerals that go into batteries, and similar environmental impacts can be expected from other types of mining operations. Consider that manufacturing 1 pound of battery requires mining, moving, and processing between 50 and 100 pounds of various materials, and it requires the energy equivalent of about 100 barrels of oil to fabricate enough batteries to store the energy contained in a barrel of oil[6].
Note that environmental impacts from battery manufacturing and recycling processes are also significant, but I have focused on the relatively larger impacts from mining for simplicity. However, note that most battery manufacturing and recycling operations currently occur outside of the U.S., because of the difficulty in complying with applicable environmental regulations, and the common complaints that battery companies receive from surrounding communities. I did not compile this information to argue against manufacturing batteries, but if we’re manufacturing the batteries to reduce environmental impacts from, say, combined cycle natural gas plants, our current technologies are likely to result in greater cost and greater environmental impacts.
Social Impact
Mining has not only played a significant role in the development of the environmental movement, but it has also played a pivotal role in the development of the labor movement. Mining is an inherently dangerous and difficult activity, and history is replete with examples of human slavery applied to minerals extraction. Indeed, mines were supplying much of the demand for slaves in the Roman Empire of 2000 years ago. Siddharth Kara’s book, Cobalt Red: How the Blood of the Congo Powers Our Lives, describes how mines in the Congo – which currently account for 70 percent of global cobalt production – systematically exploit barefoot, impoverished children and pregnant mothers to produce cobalt for western markets.
Aside from the social impacts from the labor demand for mining battery precursors, there are the impacts associated with the geopolitical tensions caused by the demand for the minerals. In recent years, we have seen such tensions affect the relationship between the U.S. and several parts of the world, including China, Bolivia, and Afghanistan, to name a few. The photo below illustrates a Tweet from 2020 that puts a very fine point on this issue.
Scalability
Even if we can somehow address the cost, environmental, and social challenges associated with battery production, it is unlikely that we can scale battery production to meet ambitious renewable energy objectives. For example, a recent study from an energy policy think tank in Boston found that meeting 80 percent of California’s electricity demands via renewables would require 9.6 million megawatt-hours of energy storage, which is 64 times greater than the state’s current storage capacity of 150,000 megawatt-hours[7]. Despite California being one of the largest purchasers of grid-scale battery products, most of this capacity is pumped hydroelectric storage.
Look at this issue one other way: 1,000 years of production from Tesla’s $5 billion Nevada Gigafactory at current rates would only produce enough batteries to store two days’ worth of U.S. electricity demand[8].
Final Thoughts
Despite the challenges associated with using grid-scale batteries, they can help us solve specific problems, such as local power backups and future displacement of relatively inefficient natural gas “Peaker” plants. Batteries are unlikely, however, to be the best solution on a cost, social, or environmental basis for areas that have extended periods of the year without sufficient wind or solar power generation.
[1] https://www.technologyreview.com/2018/07/27/141282/the-25-trillion-reason-we-cant-rely-on-batteries-to-clean-up-the-grid/
[2] 2023 US electricity demand was approximately 4,000 terrawatt hours. The capital cost for new combined cycle plants is approximately $924/kw (https://www.eia.gov/todayinenergy/detail.php?id=31912; adjust to 2024 dollars). These plants have a capacity factor of approximately 57 percent.
[3] https://poweringcalifornia.com/oil-gas-investor-batteries-cannot-save-the-grid-or-the-planet/
[4] What drives capacity degradation in utility-scale battery energy storage systems? The impact of operating strategy and temperature in different grid applications. Available online at https://www.sciencedirect.com/science/article/abs/pii/S2352152X21012147.
[5] This ammonium nitrate fuel oil mix (ANFO) is the same explosive used by Timothy McVeigh in the Oklahoma City bombing.
[6] https://poweringcalifornia.com/oil-gas-investor-batteries-cannot-save-the-grid-or-the-planet/
[7] https://www.technologyreview.com/2018/07/27/141282/the-25-trillion-reason-we-cant-rely-on-batteries-to-clean-up-the-grid/
[8] https://poweringcalifornia.com/oil-gas-investor-batteries-cannot-save-the-grid-or-the-planet/