That's not relevant in the short term. There are so many things using propane right now and it's a lot easier send them "renewable propane" than to entirely retrofit them to be electric.
I see statements like this every now and then, and I really wonder where that comes from, because that is not at all obvious, and most likely in most cases wrong.
If you imagine that "renewable propane" is something that you can just get, then it may appear easier to use your existing devices. But it's not. It's something that is not produced at any meaningful scale anywhere. There are no industrial processes to do so yet. You're talking about creating a whole new industry using technologies that don't exist yet, and by the way, a new industry that needs massive amounts of renewable energy. A lot more of that renewable energy compared to direct electrification. Nothing about that is easy.
This whole conversation is a hypothetical. Restricting the discussion to only existing technology makes no sense.
As opposed to...replacing every single ICE with an all-electric equivalent. I think scaled up renewable propane would be a much cheaper cost overall than rebuilding every single vehicle in existence.
I don't think you have any realistic idea about the energy costs of synthetic hydrocarbons. We're talking about something in the range of 5x the amount of energy you need. Think 5x the number of wind turbines and solar panels, and then reconsider if you still imagine that is a cheap solution.
This could make millions of older cars cleaner, also in the developing world. LPG is already cleaner, would benefit the developing world, and ICE engines can be produced without needing exotic materials, can be recycled 100% by smelting, are a proven, well known, durable technology, unlike lithium batteries (which are also proven, but recycling and exotic materials are problematic), and are and will be a popular technology in the developing world for a long time.
Also it would allow for cheaper and cleaner cars in the developed world, where not everybody can afford the electric dream many here are living.
It would also be somewhat suitable for long haul and heavy machinery, but most likely in a hybrid drivertrain setup.
Also it would solve the big issue of the German home heating and industry: how to stove away the sun and wind from the summer to the winter, when in the windless dark days nowadays coal is burnt, as battery of hydro storage cannot be scaled beyond a few days capacity at extremes.
There is already built, or cheap technology to gas powered solutions, no need to transition to new technology hastily. This would give runway to the green transition, as it could be net zero carbon footprint solution with less disturbance to the existing solutions.
Like it or not, internal combustion cars have many advantages, a big one being that they can run on different fuels. Converting to green LPG or (my pick) methanol will have to happen if we're serious about reducing transport emissions, because it's the only immediate non-cost-prohibitive option.
E85 does that even better, as the cost of being less dense. But it cools so much better you can run higher boost.
What about LPG?
And if we want LPG to be something we still have to deal with legislation, like in many countries you can't park in an underground garage with LPG.
They dump extra fuel to prevent knock. It's hard to melt cylinders.
> can't park in an underground garage with LPG
And yet people park. I haven't heard about an accident in the last 5 years. Maybe it could be managed by an extra detector?
LPG engines could be excellent generators (back ups or range extenders for cars and trucks). The emit less particulate matter and NOx.
For engines getting smaller: the LPG operation of petrol engines provides lower power output (and lower torque), so an uptick in LPG powered (dual fuel?) cars would probably mandate slightly different engines sensible (bigger ones), the market would surely adapt to it.
E85 would also be fine if it wouldn't be manufactured from intensively farmed monocultural agricultural products, which make it totally non-sustainable and non-renewable factoring in the sustainability problems of industrial agriculture (soil erosion, carbon depletion of soil, death of soil microbiome, groundwater depletion, etc)
The parking ban for LPG in closed garages is a real problem, I have faced it myself. Though it is justifiable, but then it would also be justified for the BEVs as there were cases already where (heat from) a battery fire compromised the structural integrity parking complexes, so it is a manageable risk probably, and probably mostly legislative.
I'm not sure why parking with LPG is a problem but parking with 10-20 gallons of gasoline is not?
In case of a leak there is a risk in case of a not-ventilated enough underground garage it is possible that the gas accumulates in the lower parts before it can be sensed/sniffed, and a mix of just 2.1% with air is already at risk of explosion if a spark is generated.
Security norms changed in the EU around 2001, the norm is the ECE/ONU 67-01 (though different countries may have implemented differently in the local Law) and LPG powered cars conforming to that standard are allowed (generally) to be parked in underground garages BUT only on the first underground floor and only if the garage is conforming to some (earlier) ventilation standards.
AFAIK cases of explosions/fires related to LPG car tanks are extremely rare (thanks also to the added safety measures mandated by ECE/ONU 67-01), whilst fires/explosions originated by domestic LPG use, while not common, are more common than what they should be (the tanks in themselves are generally safe, but the - often underground - pipings often are not).
IIRC, solar now gets to about 3$ per Mwth, so purely energy cost would be about 0.33$ per kg of propane if 100Mj of input energy per kg of propane stands for that electrolyser plus stated 13Mj for Co2 capture for 1 kg of propane. So, the cost is not negligible, but could be competetive even now, and solar is likely to get cheaper.