lenaitch
Senior Member
They probably said that about oil at some point.
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- Thread starter kEiThZ
- Start date
MrGoose
Active Member
What is finite in this equation?
Electricity (from the sun and wind) + Water => Hydrogen + Oxygen
Hydrogen + Oxygen => Energy + Water
Water => Hydrogen + Oxygen => Water => ...
lenaitch
Senior Member
No doubt there is a lot of water - in all of its states. CalTech estimates about 326 million trillion gallons; about 97% being saltwater. Best as I can tell the general scientific consensus is that it is a closed system, although there was one online article I saw that posited computer modelling suggests the earth can create it deep in the core.
According to Wiki, electrolyzing hydrogen out of water takes about 50-55Kw of energy to create 1 Kg of hydrogen. They say that is relatively efficient - I'll take their word for it.
The problem to me is that once water becomes a commodity on an industrial scale, all bets are off. At 50-55Kw/Kg, do the math for energy input required. Countries that don't have access to seawater will go after fresh water to participate in the market. It will be little different than the current petroleum industry. When great gobs of money are involved, ethics regarding ground water, 'glacier farming', etc. become topics.
I don't consider water as a 'renewable' because it is being chemically destroyed in the process. Wind power converts kinetic energy, but the air is unchanged. Solar panels chemically convert radiant energy that would otherwise simply get absorbed by the earth's surface (I suppose the source is finite, but not because of human consumption).
According to Wiki, electrolyzing hydrogen out of water takes about 50-55Kw of energy to create 1 Kg of hydrogen. They say that is relatively efficient - I'll take their word for it.
The problem to me is that once water becomes a commodity on an industrial scale, all bets are off. At 50-55Kw/Kg, do the math for energy input required. Countries that don't have access to seawater will go after fresh water to participate in the market. It will be little different than the current petroleum industry. When great gobs of money are involved, ethics regarding ground water, 'glacier farming', etc. become topics.
I don't consider water as a 'renewable' because it is being chemically destroyed in the process. Wind power converts kinetic energy, but the air is unchanged. Solar panels chemically convert radiant energy that would otherwise simply get absorbed by the earth's surface (I suppose the source is finite, but not because of human consumption).
crs1026
Superstar
At least, the water consumed in hydrogen fuel use comes back to earth as rainfall and reenters the cycle. Whether the planet would be different if all our energy use came from hydrogen, with that much added humidity entering the atmosphere, I don't know.... but it might be a better problem to have than constantly increasing CO2 levels. We need to start returning carbon to the ground somehow.
Wind and solar are at least renewable. I imagine geothermal and good old thermal reclaimation may add to the mix. Even burning biomass is at least a closed-cycle proposition.... plant to wood to firebox to smoke to plant.
But getting back to AV's and EV's, if we ever truly come to grips with carbon, the new cost of energy will disrupt a lot of things. Even if there is a labour free vehicle to haul them, other costs will prohibit a lot of things and create new opportunities. Rubber tires on ashphalt (both take a lot of energy and wear out fairly quickly) has some obvious limitations.
- Paul
afransen
Senior Member
Water for hydrogen synthesis would be a tiny slice of water for industrial or agricultural uses. And in most cases it would be converted back to water in relatively short order to release the chemical energy. That would be by using it in a fuel cell or burning it directly.
afransen
Senior Member
One interesting consideration is that lighter vehicles put considerably less wear on roads. Without the cost of a driver, I would not be surprised to see trucks to start shrinking again.
DirectionNorth
Active Member
With more trucks to carry the same amount of freight, maintenance and CAPEX would both rise. I don't see trucks shrinking unless some kind of regulation is implemented.
MrGoose
Active Member
I hope you know what competitive advantage is in economics. Countries are going to buy hydrogen from whichever producers can make it the cheapest, they're not going to be digging groundwater to hydrolyze it. That probably means huge coastal solar and offshore wind farms making hydrogen extremely cheaply to sell around the world.
So coastal deserts and offshore continental shelves will be where hydrogen gets made.
The Saudi's stay energy giants, you'll see Australia and Chile get into it, Baja California, North Africa all become energy producing regions.
Errr. But water is re-created when hydrogen is combusted. So it goes back into nature i.e. renewable
rbt
Senior Member
Agreed. I don't see inter-city truck sizes being reduced. Fleet (tractor) standardization is of non-trivial benefit for both manufacturing and maintenance, and we need at least one model capable of hauling a standard container so this seems the obvious standard to follow.
But very few retailers take a full truckload of a single product direct from the factory.
So the last-mile delivery to retailers within urban areas is a different scenario. Instead of the large Gordon Food Services trucks that serve Rabba, McDonald's, Starbucks, etc., they might send a small vehicle with a single stores delivery and require staff at the store to unload it rather than sending an employee of their own. In exchange, stores will get much more flexible delivery schedules, and eliminate the necessity to order 12+ hours in advance.
afransen
Senior Member
Equatorial deserts will all be very attractive places for solar farms. When people say that we need massive grid energy storage to use renewables, they are not considering that we'll just have dispatchable demand rather than vast storage. A lot of renewable energy can just be sunk into synthesizing chemicals for the chemical industry. We just need low capex electrolyzers that can be turned on when there is excess power and turned off when there is not. Hydrogen is not merely a storage medium for transportation energy (I think it's inferior to batteries in most ground transport applications on an efficiency basis), but a huge feedstock for the chemical and materials industry. We need to replace coal for reducing iron ore used in steelmaking, and that replacement will be hydrogen. Similarly for producing other important chemical feedstocks such as ammonia, etc. It's much easier to store the useful chemical products as a way of managing variability in energy output.
afransen
Senior Member
Regulators may consider tightening restrictions. Shippers would already like larger trucks than are permitted currently, after all (only limited by current regulation). Having to build all of our roads to take the abuse of heavily loaded trucks imposes a lot of cost on cities.
lenaitch
Senior Member
Proximity will likely enter the equation as well. Cost of production is only part of it. Cost of handling and transportation will also be an issue, particularly when dealing with a compressed gas.
Profit will still be a consideration. We still suck crude out of sand even though it is discounted because of the costs.
You are right about hydrogen having water vapour as an exhaust component. I don't know enough of the process to understand the relationship of water in : water out.
*****
Even though costs might come down with AV trucking, carriers will still lobby for large vehicles to reduce remaining costs. Ten things travelling from A to B is still more expensive than five. There is still maintenance and operating costs.
afransen
Senior Member
Conservation of matter. There is no shortage of water on earth. The only concern about water availability is about localized availability of clean, fresh water.
kEiThZ
Superstar
Absolutely. But regulator and public acceptance is quite the hurdle here and it's a step change. Even a remote operator requires substantial autonomous capabilities since that remote operator isn't dedicating 100% of their time to one vehicle.
kEiThZ
Superstar
The thing that I struggle to understand is why AEVs wouldn't lead to more intermodal shipping. If you remove the driver and lower fuel costs, then return is entirely about asset utilization. Why send one container on one truck across the country when you can have that truck pick up containers and drop them off at the transloading terminal in town all day, increasing utilization?
There may be high value JIT goods that justify a single truck driving across the continent by itself. But for a lot of commodities, I imagine rail and trucking companies can leverage automation and lower fuel cost to improve the speed and efficiency of transloaded shipments across North America.
The closer we get to full automation, the closer we get to physics dictating operating costs. And there will be some threshold distance where steel on steel beats rubber on asphalt.