Finance bro decides tweets are better evidence than physics… nothing to see here
Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably
41–50 of 205 posts
Re: Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably
#42I'm not sure he brings anything new to the argument, well except a disdain for physicists.
Re: Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably
#43Current lithium batteries Tesla - 270+Wh/kg, cheap AliBaba - 250+Wh/kg.
Gasoline/jet fuel - 12KWh/kg, with 30% thermodynamic efficiency - 3.6KWh/kg. If one takes into account piston engines weight and their expensive maintenance or how expensive jet engines overall, the electric seems to have a very good niche of short range planes, and for multi-rotor VTOL it is unbeatable.
Re: Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably
#44Earlier quoted context omitted.
Why can't cargo ships deploy floating solar panels to power the ship motors?
Because floating solar panels add drag proportional to their area, and it takes a lot of area of panels to power a motor that is sufficient for a cargo ship even without the added drag of the panels. Also, because oceans and the things one runs into in them aren't easy on solar panels being dragged along by cargo ships.
Would make more sense to produce chemical from solar energy harvested on the water fuels, collect the fuel and then use this with ships
Re: Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably
#45Earlier quoted context omitted.
Currently, ships need human sailors. They perform maintenance aboard ship as well as have legal oversight of the craft. We are not yet able to replace the crew with automation. It's difficult to find skilled crewmembers willing to sign up to extremely long rotations away from home.
It just takes money. $100k-$300k/yr is plenty to have your pick of pretty good people, especially if there are any perks like the food being halfway decent (should be basically a given if you have to pay the chef a lot anyway).
With a fraction of the money, you pay for energy to move faster ...
Re: Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably
#46Flight is a luxury of the current times that will likely not last another 100 years except for the very rich.
I believe that by 2050 synthetic hydrocarbons made from carbon dioxide and clean electricity will be deliverable at a real (inflation adjusted) cost less than than 3x current oil prices, on an equivalent-energy-content basis. That could more than double the costs of a transatlantic flight, but still wouldn't price it out of reach of the upper middle class. Synthetic methanol made with renewable energy has already bee…
Just build more nuclear power plants. There’s absolutely no reason why modern civilization still needs to rely so heavily on hydrocarbons. Unlimited electric energy, with a electrified rail network, public transportation and EVs for commuting, should take care of most use cases, except maybe a few where the energy density doesn’t make sense.
And don’t even get me started with the “our grid cannot handle it” nonsense. If it cannot, then make it so that it can. When this country started off, we didn’t say “our roads cannot handle the cars”, instead we built them, quite a lot of them. We can do that again.
Re: Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably
#47Flight is a luxury of the current times that will likely not last another 100 years except for the very rich.
Why do you say that? Typical fuel consumption values for passenger aircraft are 2.5-4 liters per 100km per passenger. So if you fly 1,000km, you'll use 25-40 liters of fuel. At current prices (around 60 cents per liter), that's $15-25 worth of fuel.
A liter of jet fuel contains 35-38 megajoules of energy, which is around 10 kilowatt-hours. Assuming 5% efficiency of using CO2, water, and cheap solar electricity (3 cents per kwh) to synthesize fuel, the cost of input energy per liter would be around 60 cents, which is the same as current fuel prices. The actual cost would be higher because you need to pay for the plant, workers, consumable catalysts, transporting the fuel to airports, etc. But real world efficiency would likely be higher than 5%. Also solar panels are still getting cheaper and more efficient, so 3 cents per kWh may be considered expensive in a decade.
Even without electric aircraft, there's no reason in principle why aviation needs to be expensive or bad for the environment. If demand for petroleum causes prices to increase enough, synthesized fuels will become economically competitive.
Re: Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably
#48I remember seeing loads and loads of analyses like this back in the 2000s on a site called The Oil Drum about why electric cars would never work at scale. (Spoiler: My family has two EVs.) They always assume that the technology will never get better, that industrial economies of scale don't exist and therefore that prices don't decrease with scale, that currently developed reserves of resources like lithium equal total reserves, etc.
I do think it will be a while before electrification of long haul aviation is practical. Aviation -- all of it -- accounts for only 7% of global oil consumption as of 2024. We could cut oil consumption by more than 80% without touching aviation. Most oil is burned in cars and trucks and those can be electrified today, so we should focus our energy on that and on replacing fossil fuels in electricity generation and take the win there.
Related tangent:
The popularity of toxic dogmatic pessimism on the political left is really problematic. It stops people from offering positive, expansive visions of the future. It's one reason the fascists are winning by default. They don't buy this shit, so they tell stories about the future that aren't "and then we all die in a great Malthusian catastrophe, the end." The fascist vision of the future sucks, but it's better than that, so it wins hearts and minds.
Ask yourself: what if our civilization doesn't collapse? Then what? The assumption that it will collapse prevents people from thinking about the future. Malthusianism is a thought stopping cliche.
Re: Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably
#49I recently read The Ministry for the Future by Kim Stanley Robinson, and one of the ideas in it that I thought was very good was replacing our cargo ships with wind-powered ships, basically giant sailing ships. In the book, they were incredibly slow, with shipments taking months to complete, but if supply lines were set up correctly, that wouldn't matter for a lot of cargo. Cargo ships are a massive CO2 contributor,…
We should not under-estimate the need for speed in supply chains. Predicting future demand is hard. To be more specific, we're talking about predicting ~100M unique products (the order of magnitude that moves on the pacific) and some of them have very lumpy demand (e.g. invent a new product, but it depends on 100 other obscure products).
Re: Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably
#50This appears to ignore the new technology that electric brings in: Reduced maintenance, (for aircraft) reduced weight in other parts of an aircraft, new propulsion capabilities that increase efficiency of the energy used, new performance envelopes (like flying much higher because the physics are totally different), etc etc. Sure. Take an existing vehicle optimized for burning things and just swap that small part and…
> reduced weight in other parts of an aircraft
The bigger problem is that the overall weight increases. Rearranging the COG doesn't really matter when most of your energy is spent literally fighting gravity.
This is the first thing that popped up in google when I wanted to compare gravimetric density between gasoline and lithium ion batteries. Gasoline is still approximately 30x denser. That is at least one revolutionary breakthrough in battery technology away, if not several.
https://research-archive.org/index.php/rars/preprint/downloa...