Most definitely, chemical energy storage is fantastically dense.
I think that as intermittent renewable energy sources get cheaper and cheaper, in addition to time-shifting of arbitrage from batteries, energy storage in chemical bonds may make sense. Methods to create synthetic fuels from electricity are in their very early days, and all of them are terribly inefficient; most go through hydrogen and that step alone results in a huge loss of energy.
So for applications where energy density is needed, e.g. jets, the fuel costs will just be that X% higher than being able to use straight electricity + battery.
I can definitely imagine a world where creating synthetic fuels from excess grid energy is cheaper than fossil fuel extraction, but it involves tons of research and development in those synthetic fuel methods, and many decades of improving renewable technologies at their current rate.
From what I understand, with assorted chemical energy storage technologies you can get a (for our purposes) arbitrarily high power density... as long as you're also willing to deal with arbitrarily high volatility. See stories about laptop batteries igniting for an example just with current batteries.
Of course, if you're talking about scifi theoreticals, the thing to do would be to calculate the energy from mixing X/2 volume of matter with X/2 volume of antimatter (presumably with some amount of the total volume skimmed off the top for containment structure).
As I said below (or possibly above) this material is only energy-dense when it's in its most compressed state. To get the energy out you have to expand it again, at which point you find that you need a vast apparatus to store your energy.
Remember, the state of the art in energy storage is a metal tank filled with liquid hydrocarbons. It's pretty damn hard to beat for price, reliability, safety [ * ] and energy density. What we really want is a more efficient way of producing those hydrocarbons out of water, CO2 and energy.
[ * ] Relative to most ways of storing large quantities of energy, that is.
Scalable? Compressed air and reservoirs are about the opposite of energy-dense and require a lot of space per unit energy.
I'm optimistic about the role that energy storage can play in converting green tech to base-load capability, but it seems like it requires some technological advances unless you want to devote huge territories to becoming low-density batteries.
Energy-dense storage is always inherently energetic, that's the definition of what energy storage is!
Flywheels explode.
Dams burst.
Fuels burst into flame.
Batteries catch fire.
Hydrogen explodes.
The difference is the relative rate. Batteries are very safe! You probably have one in your pocket on a daily basis and you don't stress about it.
Hydrogen needs special handling by professionals using constantly monitored specialised containment vessels or it explodes.
Those "well publicised scandals" you reference? Something like 90% of them are being promulgated by traders with a short position in TSLA. As you can imagine, they're not exactly unbiased.
To quote an actual analysis, not frothing-at-the-mouth ranting from day-traders losing their shirt because Tesla is doing well:
"Regarding the risk of electrochemical failure, [this] report concludes that the propensity and severity of fires and explosions from the accidental ignition of flammable electrolytic solvents used in Li-ion battery systems are anticipated to be somewhat comparable to or perhaps slightly less than those for gasoline or diesel vehicular fuels. The overall consequences for Li-ion batteries are expected to be less because of the much smaller amounts of flammable solvent released and burning in a catastrophic failure situation."
It's a "hard-headed" engineering look at our energy options written by a physicist. It might be a bit outdated (published in 2008), but when it came out it was the best compendium I'd seen.
We've got a really good storage medium for energy.
Liquid and gaseous hydrocarbons.
They can be synthesised, in a carbon-neutral fashion.
Other storage methods, including batteries, molten salt (thermal), and CAES are likely to also be used. But there are some things for which bulk liquid fuel still wins.
That high density energy is going to need some good fire protection. Excited about the increased density coming out of energy storage - these breakthroughs take a lot of research work.
It looks like diesel holds ~10,700 Wh/kg[1]. That’s over 40 times the volumetric energy density.
I hope people find an electrical energy storage system (ie a battery) that’s cheap, and with high mass and volumetric energy density, soon. That would be huge for solving the impending climate (and pollution) crisis.
Your largest-scaling options are thermal storage (molten-salt thermal, not to be confused with molten-salt electric batteries), compressed air energy storage (CAES), and pumped-hydro. The last as with hydroelectric dams is limited by available sites and environmental impacts.
Any thermal storage or thermal-process generation (e.g., molten salt thermal storage, synfuel-based generation) will be limited by Carnot efficiencies, with about a 30% energy recovery to thermal input possible. Hydrolysis loses about half of input energy, hence the 15% return on synfuel storage.
Synfuels are another option. Most of these involve creating hydrogen, many (and the ones I tend to favour) will then combine that with carbon and/or oxygen to create hydrocarbon analogues or alcohol. These are very-long-term stable, and have high energy densities. They're valuable for specific uses already (portable power tools, vehicles --- especially off-road or remote, aircraft, and marine shipping). The total net energy recovery is low, on the order of 15--25%, but the storage capacity, the storage durability, the handling characteristics, safety, and extensive extant experience and capital for storage, transport, and utilisation, are all positives.
I've followed the electric battery story reasonably closely for about a decade. It's characterised by big promises and relatively low delivery. LiON is likely the best light-weight battery, for mobile and portable applications, simply based on chemistry. There are only so many light atoms, and the ones lighter than those we're using are exceedingly anti-social. (Notably flourine and chlorine.)
Air-metal, molten-salt, and molten-metal batteries might afford large-scale capabilities, though most research seems to have had limited success. All involve inconvenient behavioural properties of the electorlytes and cells themselves. None are well-suited to mobile applications. Several should be kept some distance from other infrastructure (e.g., residential/commercial zones, etc.).
Energy banking through direct thermal storage (hot water, ground/geothermal heat/cold storage, etc.) are possible, though would require considerable revisions to existing land-use and infrastructure interconnections. Reducing overall energy loads through passive designs minimising heating, cooling, lighting, and other loads, is also probably a factor.
We're headed to a future in which energy economics will be markedly different from those of the past 50, 100, 150 years. It's those economics which have shaped our activities, infrastructure, and land use. I strongly suspect all three to adapt substantially to the new regime. Assuming that the lifestyle we've become accustomed to will continue forward is probably at odds with future realities.
I'm not sure that's a fair comparison. We have plenty of energy, in the form of untapped solar and wind, for example. The challenge is storing and distributing it, for which energy dense hydrocarbons are very effective. (Even coal is more energy dense than lithium ion batteries, and that's nothing compare to oils and its distillates).
There was an interesting article discussed at length on HN recently about using electrolysis for synthesising propane, which along side the book The Material World has made me start questioning batteries as the storage solution of the future.
There's always room for improvement, but it's starting to get within range of the fundamental limits.
Fundamentally, non-nuclear energy storage is limited by the strength of chemical bonds. For combustion, you're taking chemical bonds of high potential energy, breaking them apart, and rearranging the atoms into molecules with chemical bonds of lower potential energy. The energy difference is the heat produced by the combustion. The situation is similar in batteries, but in addition to rearranging atoms, free electrons are also liberated or consumed, with the bond energy difference going into that. For something like a mechanical spring, the winding force distorts the chemical bonds without breaking them, treating them like extremely tiny springs, with the same principle of operation as the big one. In all cases, the chemical bond strength determines how much potential energy can be crammed into the system.
For example, Wikipedia claims that flywheel energy storage (a "battery" where you just spin a disc faster to put energy in, and use it to drive something to get energy out) tops out at about 400Wh/kg. Lithium-ion batteries top out around 250Wh/kg, somewhat similar. Gasoline has a vastly better energy density at around 12,000Wh/kg... but gasoline needs to react with oxygen to release that energy! In fact it needs to react in an approximately 4:1 ratio, so the total mass going into the reaction is 5x the mass of the gasoline alone, making for an energy density of about 2400Wh/kg. Still much higher than batteries, but not outlandishly higher. I believe the difference would be because it's much easier to turn strong chemical bonds with a lot of potential energy into heat than it is to turn it into electrical potential.
You can see how reacting with the air gets you a huge advantage when it comes to how much stuff you need to carry around with you to store any given quantity of energy. And you can also sort of see how they all end up hitting the same basic limitations in the end. If you want to go further, you need take advantage of a stronger force with more potential energy, like the strong nuclear force.
(Gravity would be another possibility. If you could store energy by raising and lowering the orbit of a heavy object orbiting close to the Sun, you could get a pretty high energy density. Or if you want to go more exotic, store energy in the rotation of a neutron star or black hole. These approaches, however, pose even more difficulty for adaptation to automobile propulsion than the nuclear option.)
Energy storage is easier than fission or fusion. We've just been working on the other two problems for ten times as long. Grid energy storage became financially viable maybe five years ago and there are already startups in compressed air and sodium-ion batteries (which can be potentially much larger/cheaper than lithium-ion at the cost of being less space-efficient). Nuclear energy has been financially viable forever and it took an existential crisis for the richest nation in the world to devote all of its resources to it for years to make it happen.
There are other storage technologies being fielded...they haven't been popular because their energy densities are low...but if you have a 2000 lb hunk of Iron Aire battery next to your house, who cares? (https://www.popularmechanics.com/science/energy/a42532492/ir...)
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