However we can look at what possible applications of rechargeable batteries are, and how known reserves fit into that picture.
Humans are looking very hard to replace our go-to energy storage media: solid coal and liquid petroleum, both of fossil origin. We'll have to replace them under one of two circumstances: we exhaust them, or we cannot continue to abide the CO2 they produce. We're likely to run into both constraints within the next 20 years, if not already.
And when you start scaling known reserves of known battery component minerals against the task of providing, say, affordable transportation to a large portion of the planet's population, or even that portion which presently owns cars, the math starts falling apart pretty quickly.
Lithium is nice for mobile and transportation applications because it's light and has a high storage density relative to mass. Lead-acid batteries also work, and there's probably enough lead to supply a lot of automobiles, but it's messy and toxic and heavy.
More likely: molten-salt or liquid metal batteries. They're heavy and have lower power densities, but the raw materials are cheap and abundant. Thermal storage (again, molten salt, but used as a heat transfer fluid) and flywheels (very expensive relative to capacity, and having their own engineering challenges) might also see application, the latter having benefits for being able to respond very rapidly to large changes in supply or demand.
>Humans are looking very hard to replace our go-to energy storage media: solid coal and liquid petroleum, both of fossil origin.
So you're ignoring the stored energy vs. energy storage distinction. Yes, yes, oil and coal are storing energy from the sun from a billion years ago. But the energy there is already stored. You can't replace that by making a better battery, you need somewhere to get the energy to charge your battery. If you have a cost effective source of energy (wind/nuclear/solar/etc.) to replace them, you can at worst produce carbon-neutral oil synthetically, though alternatives may be more efficient. That doesn't mean storage isn't a problem (efficiency is king there), but it's a different problem -- if we solved the supply problem then regardless of storage we could shut down existing coal and oil fired electrical generating stations. If we only solved the storage problem we would still be burning coal to make electricity.
> So you're ignoring the stored energy vs. energy storage distinction. Yes, yes, oil and coal are storing energy from the sun from a billion years ago.
While that's an astute observation, it's not my point.
It's also somewhat imprecise: most petrochemical deposits were made ~650 - 65 million years ago. But that's just a nit.
I'm not concerned with where and when existing hydrocarbons were deposited. Merely their very high energy density and (for now) extremely high prevalence. High enough that it's more feasible to operate cars by combusting petroleum than it is to run them on batteries with 10 year lifetimes and 93% recoverability in recycling, simply because there isn't enough accessible lithium on the planet to create enough batteries to replace the cars already on the road.
Even if you had a cost-effective energy source, lithium-ion batteries aren't going to give us enough storage capacity. Due to a shortage of storage medium, not energy.
Which means something else has to give: we don't all own private automobiles (leasing or hiring autonomous vehicles when needed might make this possible). Or we use other storage media: lead-acid, flywheels, compressed air. Or, as you suggest (and I suspect), synthetically generated hydrocarbons, either liquid or gas.
The known efficiencies of this last process are low: at best, maybe 10% of incident sunlight, more likely somewhere between 0.1% to 1%. Which is actually far better than the net efficiency of the production of existing fossil hydrocarbons, it's just that they've accumulated over hundreds of millions of years. As the paper below illustrates, in one year (1997), human fossil fuel consumption amounted to some 422 times the plant matter fixed via photosynthesis (net primary productivity or NPP). Fossil fuel consumption from 1751 - 1998 corresponds to over 13,300 years of NPP. Which is actually somewhat less than I'd have thought.
Net photosynthetic efficiency is around 2.4%. Conversion of biomass to hydrocarbons is the great unknown. Transportation amounts for roughly 1/4 of global energy use. I'll assume that large measures of this might be substituted by other than liquid fuels (EVs, human power, electrified passenger and freight rail, substituting high-speed rail for air), but a significant portion of long-haul land, water, and virtually all air traffic will likely require a highly dense chemical fuel. That will mean one or more of: synthetic (carbon-neutral) hydrocarbons, carbon offsets while continuing to use fossil fuels (while they last), and/or a hell of a lot less transportation. Or create a runaway greenhouse situation.
Frankly none of the options is great.
Replacing all present fossil fuel use with existing biomass would require 22% of the present total primary productivity of the planet, a 50% increase of the amount of NPP humans already consume. And that's if we're counting on using biomass directly, not relying on conversion to other forms (e.g.: ethanol), which drastically reduces net photosynthetic conversion efficiency. Last time I checked, we don't typically run cars on wood or straw (though ships once ran predominantly on solid coal).
Humans are looking very hard to replace our go-to energy storage media: solid coal and liquid petroleum, both of fossil origin. We'll have to replace them under one of two circumstances: we exhaust them, or we cannot continue to abide the CO2 they produce. We're likely to run into both constraints within the next 20 years, if not already.
And when you start scaling known reserves of known battery component minerals against the task of providing, say, affordable transportation to a large portion of the planet's population, or even that portion which presently owns cars, the math starts falling apart pretty quickly.
Lithium is nice for mobile and transportation applications because it's light and has a high storage density relative to mass. Lead-acid batteries also work, and there's probably enough lead to supply a lot of automobiles, but it's messy and toxic and heavy.
When you start looking to grid-scale storage, even lead, as abundant as it is, comes up short: http://physics.ucsd.edu/do-the-math/2011/08/nation-sized-bat...
More likely: molten-salt or liquid metal batteries. They're heavy and have lower power densities, but the raw materials are cheap and abundant. Thermal storage (again, molten salt, but used as a heat transfer fluid) and flywheels (very expensive relative to capacity, and having their own engineering challenges) might also see application, the latter having benefits for being able to respond very rapidly to large changes in supply or demand.