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AldoLagana t1_iy3ank3 wrote

I don't like flying, but hydrogen/oxygen made from sea water with wind/solar power. That is green aircraft fuel. Right now, hydrogen is made with fossil fuels, so again...better...just not good enough...yet.

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RevolutionaryMove357 t1_iy3vt6c wrote

I thought I read somewhere about solar powered condensers that could pull liquid from the air.

I see it all working well, a greener future.

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Kinexity t1_iy4cq3n wrote

The problem is that in places where condensers make enough water are places which doesn't need them.

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travellerw t1_iy431ja wrote

Traditional hydrolysis of seawater is a super wasteful process. The water must be desalinated first using reverse osmosis or distillation. Then chemicals (usually potassium hydroxide) can be added back to the water to allow "clean" hydrogen to be generated.

Straight hydrolysis of sea water creates chlorine gas. Not only is chlorine gas highly toxic (used as a chemical agent during WWI and WWII), but very hard on equipment. Not to mention you would have to figure out how to dispose of it. Thus the desalination first.

This makes "green" hydrogen from sea water very costly. You are just better off to use that wind and/or solar energy elsewhere as you get more bang for your buck. It also means that green hydrogen simply cannot compete with natural gas derived hydrogen.

That brings up another topic. Hydrogen from natural gas can also be green. The process strips the hydrogen from the natural gas leaving you with the remaining chemicals (mostly carbon). Those chemicals "could" then be returned back down the well. Of course that also adds costs and no company will do it unless regulation requires it.

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dbxp t1_iy4q1g7 wrote

I think ATM the focus should be on electrifying the things we can easily and improving the carbon footprint of the grid. Thing like hydrogen powered ships and planes are very much in the R&D phase. Maybe we can even avoid it by offsetting via reforestation and replacing short haul flights with high speed rail.

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ArmagedonOverdrive t1_iy5gjs5 wrote

Toyota is testing hydrogen cars out in California right now. They have set up hydrogen fueling centers at gas stations in the Bay Area.

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Old_Dave t1_iy5v4o0 wrote

Honda has been doing that for 20yrs in California.

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ArmagedonOverdrive t1_iy69vxs wrote

Really? Hydrogen fuel cells? I had only seen adverts for Toyota!

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Old_Dave t1_iy6anqe wrote

Their 1st car was the FCX and then the Clarity. They're building a large hydrogen generator to demonstrate commercial power supply for buildings. It's at their Torrence, CA campus. I think it produces 1MW AC and 1150KW DC

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travellerw t1_iy6by7e wrote

Agree %100.. Right now its time to grab the low hanging fruit. When there is none of that left, then we move on to the harder problems. If we could eliminate daily personal travel and home heating energy usage that would be HUGE!

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paulmclaughlin t1_iy4t1j7 wrote

Hydrolysis is using water to split something else, you're thinking of electrolysis of water.

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Robot9P t1_iy4w0a2 wrote

Could we not use fresh water, currently abundant in the Great Lake and similar areas to avoid the desalination and Clorox problems? And I realize fresh water is not endless and with climate change, reliable. But can it jumpstart or fill a void until the tech matures?

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travellerw t1_iy6bhhs wrote

We %100 could.. However, its usually a bad idea to make a basic human resource compete with fuel. This is why fuel from crops is a bad idea.

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No-Yogurtcloset-400 t1_iy63ro6 wrote

Only 2.5% of water on earth is freshwater. Could be tricky to divert so much of that away from agriculture.

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dr_jiang t1_iy5ar4z wrote

Commercial aviation burned 95 billion gallons of jet fuel in 2019. Hydrogen has one fourth the energy density of jet fuel, and takes 2.4 gallons of water per kilogram of hydrogen if we're making it through electrolysis.

There's plenty of water in the Great Lakes (for now: we're currently turning it saline). There's not plenty of spare electricity to power the electrolysis plants, or plenty of spare money to build them, or plenty of hydrogen transport and storage infrastructure to get it from the Great Lakes to everywhere planes need to take off from.

Hydrogen has plenty of use cases where it makes sense, and its weaknesses as a fuel can be mitigated. Aviation is not one of them.

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Nyrin t1_iy5gq4n wrote

>Hydrogen has one fourth the energy density of jet fuel

Just to call out: as density decreases, fuel requirement goes up a lot worse than linearly. You have to burn fuel at the beginning of the flight to transport the fuel you'll use for the rest of the flight, and the more fuel you need, the more dire that picture looks.

The exact numbers would depend on a lot of variables (weight and distance chief among them) but most flights, even the smaller and shorter ones that are feasible with hydrogen's energy density, will need way more than four times the fossil fuel amount in hydrogen.

I do think that hydrogen (and even BEV in narrow situations) might have a place in limited aviation scenarios (very short/light flights) but completely agreed that the math just doesn't work for either of these electric modalities to replace fossil fuels in-place for long, heavy flights — and that's not a "point in time, technology will keep getting better" thing.

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dr_jiang t1_iy5ip33 wrote

I'd forgotten about the "need gas to haul gas" math. Honestly, I stopped taking hydrogen as aviation fuel seriously when the white papers came in describing the plane passenger economics.

The reference escapes me, but the bottom line was that converting existing airframes to hydrogen meant ripping out 14-20% of seats and paying 60% higher fuel costs. Barring science-fiction level advancements in the underlying technologies, commercial air travel as we know it can't exist in a hydrogen-fueled world.

No industry, no government, and no passenger is going to tolerate that.

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[deleted] t1_iy5agi1 wrote

>Hydrogen from natural gas can also be green... Those chemicals "could" then be returned back down the well.

There is currently no way to 100% prevent methane escaping from wells or distribution pipelines. Estimates range from 2%-4% of all natural gas produced leaks into the atmosphere. And fracking has shown us that pumping chemicals back down wells can have very severe consequences. Look at the earthquake data for Oklahoma over the last decade or so.

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travellerw t1_iy6cvty wrote

I agree with the leaking, however, there is tons of methane that naturally leaks out from numerous sources in the earths crust. In the grand scheme of things, the leaks would be insignificant "IF" they stopped the general burning of carbon fuels for shipping.

I don't agree with you on putting the chemicals back. Fracking is a completely different process that pumps a hydraulic fluid down the holes . Carbon capture and sequestering from natural gas hydrogen would pump the chemicals back down dead wells. It would not use hydraulic forces to try and create fractures in the crust. Simply put the unwanted chemicals back in a chamber that is now empty.

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[deleted] t1_iyahp4i wrote

I think you are confused about what causes earthquakes from fracking. They're not caused by the initial fracturing of the crust, they are caused by wastewater disposal wells, which is exactly the kind of solution you are proposing.

https://www.usgs.gov/faqs/does-fracking-cause-earthquakes

>In Oklahoma, which has the most induced earthquakes in the United States, 2% of earthquakes can be linked to hydraulic fracturing operations. Given the high rate of seismicity in Oklahoma, this means that there are still many earthquakes induced by hydraulic fracturing. The remaining earthquakes are induced by wastewater disposal.

So only 2% of the earthquakes are from the actual fracking, 98% are from wastewater disposal. If waste disposal can trigger that many earthquakes in a relatively inactive zone like Oklahoma, imagine the problems it would cause in a state like California where the majority of the population lives within 30 miles of a fault zone.

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tyranicalteabagger t1_iy69d9d wrote

There's a whole nother dimension to this problem also. Compressing the hydrogen to the necessary pressures to get descent energy efficiency uses a ton of energy also. Hydrogen is a really terrible energy storage and transport mechanism.

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travellerw t1_iy6df25 wrote

Not to mention hydrogen embrittlement. Hydrogen is a "slippery" molecule and can even escape solid steel pipes. As the molecule passes through the pipe it creates a phenomenon called hydrogen embrittlement. Steel is eventually weakened to the point of failure. This is not only a safety issue, but a maintenance nightmare. Steel pipes need to be replaced a much faster rate when used with Hydrogen. I understand there are coating now to mitigate this problem, but they add cost and complexity.

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tyranicalteabagger t1_iy6l0mu wrote

Yeah. That too. Composites mitigate it, but high pressure hydrogen is phenominally dangerous when mistakes or accidents happen. Not even so much fire, but 20000psi suddenly releasing is basically a bomb.

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niksal12 t1_iy4e1x5 wrote

There are several nuclear stations that are being equipped to generate hydrogen which will help alleviate the fossil reliance. Source

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akl78 t1_iy7pfb0 wrote

I know it’s a terrible idea but the kid in me still wants someone to skip the middle step and build a plane like Fireflash

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Mrqueue t1_iy52259 wrote

And so is some electricity but we have to take steps in the right direction. It’s very possible to make hydrogen with excess wind or solar energy once we actually fucking invest in green energy

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atehrani t1_iy69gsk wrote

I was under the impression that the volumetric density of hydrogen just isn't practical for commercial flight. The tanks would be far too large?

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plantman-2000 t1_iy4wm80 wrote

Almost everything even your Tesla is powered by fossil fuels.

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MailFucker t1_iy52nz1 wrote

Burning fossils fuels in a power plant is more efficient than burning them in an IC engine.

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AzzaClazza t1_iy7yyq1 wrote

That's true for a gas turbine plant, is it true for coal fired?

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MailFucker t1_iy86mn4 wrote

The very first result on google says the average coal plant in the US is 33% efficient, while ICE is between 11 and 27%.

For what it’s worth, basically every power plant uses a turbine.

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Meatball_pressure t1_iy3eaj1 wrote

And batteries are made of organic fairies? Don’t forget most electric grids in the US are still powered by coal power plants! Id rather bet on hydrogen tech any day and get over this battery obsession!

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69tank69 t1_iy3jiwh wrote

It’s not like hydrogen storage requires any precious metals

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dont_even_bother_ t1_iy5c5gk wrote

Coal is 20% of the US overall and falling rapidly, so this is just flat out misleading.

My state currently has 0% of electricity produced by coal. At this very moment the CA grid is currently producing approximately 75% of it energy from renewable (63%) and nuclear (8.5%).

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Meatball_pressure t1_iy5cq0u wrote

If it helps you sleep at night. Don’t feel guilty driving your obnoxiously fascist Tesla.

https://www.eia.gov/energyexplained/coal/use-of-coal.php

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dont_even_bother_ t1_iy5cyq1 wrote

I drive a Porsche Cayman S. Nothing in that link disproves what I said, in fact it confirms it.

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Meatball_pressure t1_iy5d4k0 wrote

Here’s a list of coal powered plants you can go visit in your overpriced wagon.

https://en.m.wikipedia.org/wiki/List_of_coal-fired_power_stations_in_the_United_States

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dont_even_bother_ t1_iy5dywv wrote

Well you must admit, it's a good looking wagon: https://i.imgur.com/ia2gZ2c.jpg

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Fiorta t1_iy5vaux wrote

That's looks kinda like the Panamera and not the Cayman.

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dont_even_bother_ t1_iy66eg9 wrote

Panamera is 4 door, but the design language is similar. It’s extremely similar to the 991 911, though, even sharing a bunch of parts. It’s also teeny tiny in person. Another angle gives a better idea of the proportions:

https://i.imgur.com/k5n02VH.jpg

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Fiorta t1_iy693c6 wrote

Ah shit, I was thinking of the Cayenne SUV lol

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XonikzD t1_iy3s8q6 wrote

If it's about point of use variables and if all production, transport, and useage "carbon impact" costs were equal, then hydrogen is great for personal transport. Unfortunately, production and transport aren't equal. Applications like jet fuel where hydrogen is part of a controlled reaction for thrust are way different that hydrogen applications in vehicles where hydrogen is part of the electrical discharge process to power electrical batteries that then deliver energy for motors. In the EV Vs Hydrogen dialogues online most people seem to think that hydrogen cars and busses are "burning" hydrogen and that is not the case.

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Meatball_pressure t1_iy4epz7 wrote

Elon fanboys got their crotch less panties in a bunch. I said it before and I’ll say it again, fuck EVs. https://www.bloomberg.com/news/articles/2022-10-18/bmw-group-chairman-oliver-zipse-hydrogen-cars-are-still-happening

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XonikzD t1_iy4ghoo wrote

I also am not a fan of Elon or his business practises or the mismanagement of EV marketing over the past two decades from him and any of the fanboys on that particular side of the playing field. I also, however, have been around long enough to know that each vehicle and each "fuel source" will have its proponents and its naysayers and eventually everything works out to whatever the easiest possible method is for getting something done with the appropriate tool at hand. I think every single one of these should be developed to their extent and the market should decide which one is the easiest thing to work with for the desired outcome and desired cost.

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