Do you have a link to back this number? Are these batteries rechargeable? Does the measurement include wiring, cooling, cell connections and overall structure of the battery pack?
For comparison, Tesla's (Li-ion) battery pack energy density is 160 Wh/kg, which is 0.576 MJ/kg:
https://www.pv-magazine.com/2020/02/11/energy-density-advanc...
Comparing just the gas tank to several subsystems of a battery electric vehicle is not really an interesting comparison. The closest comparison at that level is just gas vs just cells.
Overall electric is still lower energy density per weight, but is also far more efficient. The whole Tesla pack has the energy of just a couple gallons of gas but can go 400 miles.
https://pubs.rsc.org/en/content/articlelanding/2019/ee/c9ee0...
Gas still wins with a short refuel time.
My own initial experiences have been mixed. Overall advantage still goes to gas. But I think we're very close to getting this battery thing figured out. Just a few years away. When we look back it will seem like it happened overnight.
By that logic, you could say that there is absolutely no difference, because if you can imagine a car where the battery can be swapped, you should be able to imagine a car where the entire fuel tank is swapped. A tractor arrives at a station, and instead of filling up 500 litres of diesel, the entire tank is simply replaced with a full one. It wins again since fuel tanks are cheap - they are just metal and plastic after all, you can have several just sitting there, full or empty.
The fact that no one has done it yet suggests that this really isn't an issue - commercial diesel filling stations usually run at much higher pressure than your regular pumps, a truck/tractor tank fills in minutes because of a much higher flow rate.
Swapping gas tanks provides no advantage and you conveniently ignore the whole point of the batteries which is that you don't need any fuel infrastructure to fill your tanks!
A fuel infrastructure costs magnitudes less than just one battery pack. You just need a large tank and pump.
Farmers have machines and equipment for almost everything. Swapping out a flat pack? POC
Swapping batteries implies either having multiple batteries, which adds to you costs significantly, or it implies adding yet another proprietary service company putting the screws to you in your supply chain.
For instance, don't forget the fuel suppliers, tank inspectors, etc, in the supply chain on the other side.
I was just commenting on the point of refuel time.
Also, it's possible to use extended swapable batteries for such cases.
> Li-metal batteries top at around 14 MJ / kg, and gasoline is at 47.5 MJ / kg.
Wouldn’t this gap actually be very close considering that the efficiency of an ICE on gasoline is what, 30-40% at best (IIRC)?
1kg * 14 MJ/kg * 95% = 13 MJ mechanical
1kg * 47 MJ/kg * 30% = 14 MJ mechanical
It comes out pretty close!
If you want mechanical power and also heat (for keeping people, animals, or equipment warm, decreasing the viscosity of fluids, etc), ICE is definitely the way to go.
-- edit --
/u/ash points out Tesla's energy density is is 0.576 MJ/kg
1kg * 0.58 MJ/kg * 95% = 0.55 MJ mechanical
...not even slightly close.
1 kg * 142 MJ / kg * 50% = 71 MJ mechanical
The dominant solution above all else.
All those require huge amounts of energy, and batteries are not yet nearly there (as others point out, your numbers for battery energy density are out by a factor of 30).
They are also quite weight sensitive, requiring additional induced drag to be overcome at heavier weights.
Albeit in theory true, here in the outskirts of the Sahara, I have yet to find a village where I can get an electrician to fix my solar panels, though a few bottles of gasoline can be found everywhere.
If I want to burn dead leaves to run my car... well that sucks right now (moreover that isn't anymore 0 emission).
If I run off to start a farm, and I buy an existing OTS used tractor, it will have a tank that I can pour almost any flammable liquid into to make it run. If I want to plug the tractor in... well, that'll get the engine to turn over, but it won't get it moving anywhere.
If I build myself a cabin in the woods, I can burn wood or wood pellets to keep cook food, or keep warm during the winter. Alternatively, I could purchase batteries, PV panels, and the necessary charge control electronics, in order to run an electric heater.
Burning recently-alive biomass does release carbon, but it's carbon that was in the atmosphere as recently as a few months ago. It isn't zero emission, but it doesn't contribute a long-term increase to the amount of carbon in the atmosphere.
A forest is a carbon store. Burning trees puts carbon from this store to the atmosphere.
To count it as carbon neutral is an accounting mistake, that could be very costly...
Burn the dead leaves and you shrink humus (or annihilate it, depending on how much you do it), another huge carbon store. So that makes it yet another accounting mistake.
More generally, it is good practice to separate well atmospheric carbon (CO2) and captive carbone (anything in solid/liquid state). Just show that faithfully in the accounting method, and a lot of good will follow.
https://wood-energy.extension.org/is-burning-wood-carbon-neu...
But burning a preexisting forest is cancelling an existing carbon store and converting lots of solid carbon into atmospheric carbon.
The fact a forest is a carbon store is precisely why a startup such as Pachama exists: they help grow new forests to capture carbon.
Would you then just unnoticingly burn them for energy, and keep telling the customers that you just captured a net amount of carbon?
PS: oh you are jacquesm! :) didn't notice. How are you?
PPS: some critic about the link you sent me ("wood-energy.extension"): I disagree with what they say, in that fallen wood too is a carbon store, and in a forest at equilibrium the amount decomposed by fungi/bacteria is roughly compensated by the newly fallen wood. So that's just a carbon store, and if you begin to burn it you shrink this store.
It seems obvious that if you want the density of liquid fuels, hydrogen is the answer. Compromising yourself with a lower energy density substance stands as a very difficult problem to solve.
If there was a Nobel Prize for understatement, this comment would take it hands down.
New "breakthroughs" in battery energy density are a dime a dozen. They're proving incredibly difficult to bring to commercial viability, and there's no evidence that that's going to change.
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Under the worst possible conditions (not considering temperature), on the shortest day of the year, with 100% clouds and a thick layer of snow, PV panels would produce 14% as much power per day as on the longest day of the year with 0 cloud cover.
Also, electric offers you the plethora of choices in methods to produce your energy. If it's not photovoltaic, you still have many solutions. Could as well be eolian, or a dam, or hundred of people riding generator-bikes (half-kidding), or etc.
I've wondered if it makes sense for gyms to be paying for electricity.
Li-metal batteries [edit: still an immature tech] are at around 14 MJ / kg, and gasoline is at 47.5 MJ / kg.
Moreover, suppose that you are really "off-grid". Meaning, you are off any fuel supply network!! In this case precisely, you would be saved by electric-related techs, such as photovoltaic.