Do We Have Enough Lithium?
Lithium batteries are proposed as the solution to various sustainable-energy problems, for example electrification of road transport and coping with the intermittency inherent in wind and solar power.
Let's consider how far we can get based on known lithium reserves.
How Much Lithium Is There?
https://en.wikipedia.org/wiki/Lithium estimates world lithium reserves (known so far) to be 86,000,000 tonnes. This figure is a bit meaningless if it reports the mass of ore. So let's assume it reports the mass of extractable lithium metal. The same page also reports how known reserves are growing steadily each year.
How Much Lithium Will Cars Need?
I can't find a reliable source for the number of cars in the world. So let's use the figure of "1.06 billion passenger cars" on https://www.rfidtires.com/how-many-cars-world.html.
Let's hope most people can get by with a medium-sized car, for example a Tesla Model 3. https://en.wikipedia.org/wiki/Tesla_Model_3 implies the Standard Range model has batteries weighing 320kg.
A typical lithium-ion battery comprises about 7% Li - https://www.sciencedirect.com/science/article/pii/S2405844019347012.
So a Tesla Model 3 Standard Range requires 22kg of lithium.
Batteries for 1 billion cars would use 22Mt of lithium.
Great: electrifying the global car fleet would require about 25% of known lithium reserves. That sounds feasible.
Note: if the vision of self-driving vehicles materialises, we will probably require a much smaller car fleet, with many drivers cutting costs by hiring and summoning vehicles short-term instead of owning their own car.
How Much Lithium Will Renewable Electricity Need?
Suppose we switched all energy supplies to electric and wanted to store one day's worth of power.
https://ourworldindata.org/grapher/global-primary-energy?country=~OWID_WRL shows that global primary energy use in 2019 was 159,000TWh.
So daily primary energy use is 435TWh, ie 435,000,000,000kWh.
https://en.wikipedia.org/wiki/Tesla_Model_3 says that Tesla's lithium-ion batteries store 150Wh/kg.
So to store 435TWh would require 2,900,000,000,000kg of lithium battery, ie 2,900,000,000 tonne.
As per above, a typical lithium-ion battery comprises about 7% Li.
So batteries to store one day of global primary energy use would require 203,000,000 tonne, ie 203Mt of lithium.
That's about 2.3 times known reserves.
With known reserves growing steadily each year, it's seem reasonable that there will be enough lithium to store one day of global energy use to cope with intermittency in wind and solar power.
- In reality some energy demand can be met without electricity eg solar water-heating, wood-fired heating; aviation and intercontinental shipping will require non-battery energy - see Carbon-Neutral Flying and Can We Electrify Shipping?
- Good news: current primary energy use is hideously inefficient, requiring additional energy for extraction, processing and shipping of fossil fuels; when burnt to produce motor power, it's typically 40% efficient; when we switch to renewable electricity daily primary energy use will be much lower.
- More good news: in most of the world, energy demand doesn't vary much by season and sunshine is available predictably every day of the year; for most humans a single day of energy storage will sufficient.
- The real challenge comes for high latitude, energy-guzzling economies which need to find how to cope with consecutive windless, winter days.
- A proportion of electrical energy can be stored efficiently in hydro-electric dams and pumped storage.
- A proportion of electrical energy can be stored inefficiently as hydrogen - useful when renewable electricity supply exceeds demand and available storage.
- Non-essential industrial electricity users can be compensated to cease production at times of longer than normal intermittency.
- The lithium in car batteries could be used as a small part of the grid-power storage system - as suggested by David MacKay in Sustainable Energy Without the Hot Air.
Thank you to Stephen Hartley for his suggestions.
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