Big oil is getting into lithium . That's major news, but there is a catch: Lithium isn't all that big.

Exxon Mobil (ticker: XOM) spent about $100 million buying land in the Smackover formation of southern Arkansas from an exploration company called Galvanic Energy, The Wall Street Journal reported Sunday. Exxon didn't immediately respond to a request for comment.

The move, on some levels, looks like an acknowledgement the the future of cars is battery-powered than gasoline-powered. Checking out lithium appears like a smart move after all the International Energy Agency estimates that there will be

350 million electric vehicles on global roads by the end of the decade, up roughly tenfold from today EV population. What's more, if the IEA is right, EVs will account for roughly 15% of all vehicles on roads, up from less than 2% today.

Exxon will need to replace some of the demand for gasoline. The Arkansas land might have as much as 4 million tons of so-called lithium carbonate equivalent, or LCE. Lithium carbonate is one of the actual products that gets used by battery makers in lithium ion battery production.

Four million sounds like a lot, but that amount of lithium carbonate is worth roughly $120 billion at today's market prices. And that's the resource. A portion of that would be mined, and processed, each year.

Exxon is projected to generate 2023 sales of about $373 billion. It will take a lot of lithium to replace a significant portion of that revenue.

A lot might be an understatement. Exxon, Chevron (CVX) and Saudi Arabian Oil (2222.Saudi Arabi), which is better known as Aramco, are expected to generate combined sales of more than $1 trillion this year. Three of the largest lithium producers on the planet, Albemarle (ALB), Livent (LTHM) and SQM (SQM), are expected to generate lithium-related sales of about $10 billion, or roughly 2% of energy giants' total.

Lithium production, according to car industry estimates, is expected to expand five to seven fold between 2023 and 2030. Even projecting higher lithium prices, global LCE sales should amount to roughly $150 billion by 2030. Global sales of crude oil topped $2 trillion in 2022, according to data from BP (BP).

Lithium and oil just work a little differently. There might be roughly $1,000 worth of LCE in a typical EV. Lithium is only a part of the total battery which, of course, get recharged over and over again. That typical EV might travel 150,000 miles over its life. A typical car will consume, perhaps $15,000 to $20,000 worth of gasoline over the same distance.

Lithium stocks aren't reacting to the Exxon report. Albemarle, Livent and SQM share are up 1.1%, 0.2% and 0.6%, respectively. S&P 500 and Dow Jones Industrial Average futures are both flat. Exxon stock isn't doing much either. Shares are down 0.1% in early trading.