Slashdot Mirror
The Physics of the Hydrogen Economy
Spy der Mann writes "A Physics Today article entitled The Hydrogen Economy explores the possibility of using hydrogen as an energy source. The article explores the current methods, limitations, and the need for more research. For those wanting to point out the Hindenburg incident, the article doesn't talk about gaseous hydrogen only, but also about hydrogen fuel cells. My favorite quote: 'The natural world began forming its own hydrogen economy 3 billion years ago, when it developed photosynthesis to convert CO2, water, and sunlight into hydrogen and oxygen'. Interesting read for eco-fans."
1- Re the Hindenburg incident: there is now fair evidence that the whole thing happened not because the hydrogen is flamable (it was in airtight balloons, and any hydrogen leaking out was highly vented), but because of the envelope fabric, that had cellulose acetate butyrate coating, which is highly flamable and prone to cause static electricity. If the blimp had been filled with helium, a ravaging fire would have engulfed its skin anyway, but with less violence. The hydrogen gas here was a facilitant more than a cause of the disaster.
2- Hydrogen is only a vector. It is not an energy source, it's only a way to carry energy created elsewhere. There is no "hydrogen economy", just the existing energy economy with an additional vector that can be compared to batteries.
Hydrogen can never occur naturally because it always binds to some oxydizer, so, in order to get the hydrogen out, you have to crack the compound you're getting it from.
This takes energy to do, at least as much energy as you get back by using the hydrogen.
So, in order to have a large-scale hydrogen "economy", you need an alternate power source to make all that hydrogen in the first place. Basically, even though hydrogen may be extra-clean, you're just moving the pollution ardound anyways.
One prolem i think is that oil companies have been blocking the development because it would take away a huge market for them. They would lose tons of money if Hydrogen became a practical resource.
"We tend to become like the worst in those we oppose." "Perceptions rule the universe." --Bene Gesserit Sayings
1> the sun is not 100% hydrogen 2> oxidization != fusion
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
diesel requires no new infrastructure, and we can gracefully move to biodiesel as the oil reserves are tapped out.
Why is this only obvious to me? Why can't I buy a honda civic with a diesel?
love is just extroverted narcissism
..that no one ever seems to talk about with hydrogen is ENERGY DENSITY. A gallon of liquid H2 has nowhere near the energy content of liquid octane when fully burned. This means that it takes significantly more volume to store the same amount of energy.
This is the big issue with hydrogen cars--big tanks, low horsepower engines to get around the limitations. Not exactly what most consumers are after in a vehicle.
It's great for some applications, but as a complete replacement for fossil fuels I don't see it.
When you burn gasoline in a power plant, you run at one speed, the most efficient one. This means that a gallon of gas burned in a power plant will generally speaking cause less pollution than a gallon of gas burned in an automobile.
The upshot of this is that even if all of the hydrogen used in automobiles were created in power plants fueled with gasoline, there'd still be a huge reduction in the amount of pollution emitted.
This is not even getting into the fact that it is easier to create technologies to trap polluting emissions in a few power plants than a million cars.
As a thought experiment, imagine if instead of having coal fire plants generate electricity, we just put coal-based generators in everyone's house. Do you think the amount of overall pollution would be the same? After all, the electricity is just "moving around" where the coal is burned.
The final reason that this is important is that it is much easier to add new alternative fuel power plant online than it is to create an alternative fuel car. Right now, there is absolutely no way to make a car run on solar power, period. If, however, there were large numbers of hydrogen powered cars around on the road today, you could move toward non-polluting sources simply by putting a solar power plant on the grid.
So no, a hydrogen economy is not perfect. However, it is better than what we've got. It's also a first step towards an economy that doesn't use fossil fuels.
The cake is a pie
The executive summary version of this fact is that if the entire population of the earth were consuming energy at the same rate as Americans, the atmosphere would be incandescent with waste heat.
Are you on crack? Look at New York is it hot or cold in the winter? The amount of energy used by us humans is TINY when compaired to say the amound of solar radiation that lands on the earth each and every day and the net tempature of the planet stays constant because all this energy is radiated back out into space.
DO the math 24*7 the sun is dumping energy on pi * 15,700,000 sq Miles and it's all going back out to space.
It is a storage medium. And it is not perfectly efficient. Ergo, when the article says "It takes energy to split the water molecule and release hydrogen, but that energy is later recovered during oxidation to produce water." what it means ks that "later some of that energy is later recovered.
Hydrogen must take more energy to produce than you can recover from it. So our hydrogen economy is not a hydrogen economy at all. It is an economy based on some other energy source, with an exchange rate, like currency, where you lose a little to the money changer in every transaction.
So where do they imagine that energy will come from? Solar? Unlikely. Hydro? Simply not enough to supply the world's needs. Geothermal? Also not enough. All of it combined isn't enough.
And if it is enough, why waste some of it converting it to hydrogen, then back to electricity? Why not just use it directly?
The whole concept of a "hydrogen economy" is a sham. Or a scam. Somebody's making a lot of money on all that research.
But no matter how much research you do, you cannot turn hydrogen in to an energy source. It does not occur in nature in a usable form.
First, I hate that the article contains the submitter's favourite: 'The natural world began forming its own hydrogen economy 3 billion years ago, when it developed photosynthesis to convert CO2, water, and sunlight into hydrogen and oxygen'. What crap. Photosynthesis generates saccharides - chains of sugars, which are used by plants in to generate energy from respiration, just as animals do. There may be a brief moment where water molecules are split into H. and OH. radicals, but no hydrogen gas is produced or used as an energy store. Bury the plants deep undergound for a few million years and you have fossil fuels, not hydrogen gas pockets.
Now, for those of you pointing out how crap hydrogen's energy density is - you're right! It sucks. It's so hard to deal with the stuff. I mean, the only way they make it work for the Space Shuttle is to deep freeze it so that it liquifies, and it takes yet more energy to cool it down which makes it suck more...
If you read the article, it admits that using hydrogen in vehicles is very challenging. A tank full of H2 is unlikely to ever happen on this planet. Instead, the suggested vehicle storage solutions include nanostructure materials, surface absorbption/adsorption, or ionic compounds. However, cars and planes are not everything in the world. H2 gas could be used in homes and businesses instead of natural gas. Various methods of generating H2 gas from a much denser hydrogen store - such as water - are suggested: heating it up to 3000C (~5400F) using solar collectors or nuclear power, bacterial processes, and catalysts (see figure 2 in the article - looks fancy doesn't it?).
So, OK, some of the style of the article feels bad to me, but there is some useful physics in there.
This is not a sig
I do not mean by this message to imply that we cannot move to an economy that oxidizes hydrogen as a primary resource. I *am* intending by this message to point out the amount of hand waving that is going on both within government circles, the Department of Energy, the news media, etc. about the "famed" hydrogen economy. It is a much more difficult problem than the people waving their hands would like us to believe.
In contrast an energy solution built upon methane (natural gas) which is manufactured from carbon which is in the atmosphere (rather than in the ground) is a viable sustainable solution give technologies and infrastructure we already have.
We just have to be intelligent enough to (a) develop the organisms to produce the methane; and (b) channel said methane into the existiing natural gas pipeline system; and (c) perhaps develop some incentives that would bias farmers to produce solar ponds that produce methane instead of cows that produce methane. (Think about this for a second -- sunlight provides energy. Photosynthesis grows grass. Cows eat grass. Cows produce methane. Humans consume methane (but it is mostly methane we haul out of the ground that was manufactured thousands of years ago.)
Are we not clever enough to produce our own methane from atmospheric carbon dioxide in a way that creates a completely sustainable energy system?
This I ask you...
And by the way the complete genomes for bacteria that can (a) perform photosynthesis and so are able to harvest solar energy; and (b) the bacteria that can synthesize methane; are in the public databases. They are free for the taking. It will not be easy to merge them. I have some ideas as to how to do this. The point of this message however is to get you to *THINK* outside of the box.
Yes, we may get some subset of a hydrogen economy. But as most /. readers are probably good engineers you should be asking how, where and when. In the meantime a methane economy could more easily be developed and sustained (i.e. the carbon we put into the atmosphere is carbon we have previously taken out of the atmosphere).
Just a few thoughts...
A rail system like the one mentioned here recently that handles moving people around fairly densely populated areas makes sense, and extending it across larger distances even makes sense, but eliminating cars entirely really doesn't.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
"Made" seems to be the more appropriate word, IMHO.
So, what power source can we have to extract pure H2 from other materials? Well, we can have, for example, solar power.
Greetings from Wisconsin, where the development of solar power awaits only the introduction of sunlight.
Seriously: solar power is very diffuse, and the efficiencies of existing commercial solar cells are pathetic.
Now Try making oil from wood with your chemistry kit.
OK. I would use pyrolysis to convert the wood to water gas (carbon monoxide + hydrogen), a copper catalyst to convert the water gas to methanol, and the Mobil zeolite process to convert methanol to gasoline (MTG).
It's much easier, though, to convert cars to run on alcohol -- especially since most car engines are now fuel-injected and computer-controlled.
So, is hydrogen economy all that far-fetched? No, it isn't!
Yes, it is! Tell me how we're going to store hydrogen -- safely and efficiently -- in our cars. Tell me how we're going to adapt our natural gas pipelines to carry hydrogen (or tell me who will pay for new pipelines). Tell me how to make a low-temperature fuel cell that does not require expensive precious metal catalysts. Tell me where the electricity for electrolysis is going to come from.
What are you, 14 years old? You can't replace the energy economy of an entire country with promises of "Oh, we'll figure it out LATER"
Well, "big oil" (which I'm closely related to) would be happy to supply the oil for the power - after all, oil and coal are where we get our current power. They might not like the increased energy efficiency, mind you. However, the automobile lobby would be glad to be making brand new vehicles that everyone is going to need. :) And even after everyone is "updated", styles change - and even though things will wear a lot more slowly with the greatly simplified propulsion, unless you go straight to maglev for all speeds, you've still got wheels, and even stationary objects get "old" and dingy.
The "jobs" issue isn't a problem. With the improved ability to transport goods automatically, the GDP boost will easily create more than enough jobs. It might be bad for those who get laid off, but the net picture is quite good.
As for those in remote locations - if you're going to build a road out there, you might as well build a rail instead. If it's a seldom-travelled road, you can use a rather light piece of rail, just like one might use a poor quality road for such a location.
Seen on a Japanese food processor: "Not to be used for the other use."
Cute idea, but I think "staggering capital costs" is the world largest understatement. First off, you are talking about what would be by far the largest government project ever even conceived. It would make the current combined spending of the US government look like pocket change. You couldn't even contemplate such a thing without turning your entire economy over to the effort. You would need greatest tax hike in American history to fund it. No, even disbanding the military wouldn't even begin to cover the cost.
Then, you would have the fun time period in-between the completion of this new magical rail system where you would still need roads. So, somehow you need to build this track system while still preserving the road system. This is an completely unthinkable task unless you commit yourself to some serious private land seizures. If you want to make a new rail system appear out of air and not destroy the existing road system until it is done, you are going to have to tell people to vacate their house while the government bulldozes it down to make way for the greatest piece of pork ever conceived.
If you are going to cover the entire nation in this thing in one life time, you also will need a massive amount of construction crews and equipment. I don't know about you, but I have no intention of quitting my day job to be a construction worker. That means that the US is going to import a massive number of people to work these jobs and pay them, straight out of the government's pocket. Further, some has to oversee and manage the entire project and keep it on budget.
So, now we have this magical rail system, we need to continue to pay for it. If you thought a layer of tar was expensive - imagine the joys of keeping a magnetic rail system intact. Certainly you could build safety into these things, but if cars are zipping around at a 100+ miles per hour, you better be ready to jump on any repairs that are needed. The materials all costs significantly more then tar does. Further, you need to completely rewire the US power grid. The power grid as its stands couldn't even begin to handle having to support every single personal and commercial vehicle.
So yeah, really cute idea. Alls you need to do is convince people initiate the biggest government project in history, raise taxes as far as they will go, seize millions of acres of private land, some how oversee and manage this project, then once it is done devote massive amounts of government budget to its continual upkeep. No, the "GDP boost alone" will NOT pay for it. This idea is at best a recipe for making an industrialized nation into a poor third world nation, and most likely a recipe for a violent anti-government revolution. Mods, please think before you label this crap interesting. I might as well throw up my "just drive to Mars idea in family mini-van". I mean, it would work perfectly with only the small hitch of a few million miles of vacuum between here and there.
Nuclear is NOT an alternative energy source. It is a very dirty and dangerous power source. Anyone that believes that nuclear power is clean, cheap and safe has been brainwashed by the well-funded nuclear industry's public relations arm.
Or are atomic scientists or know enough about the reality, not the hype, or physics in general to know the truth. Physics doesn't lie. Coal plants put more radiation into the environment than nuclear plants. Fact. Even the worst accidents on record are not even a drop in the bucket in comparison to the fatalities caused every year by non-nuclear power generation systems. As of a few years ago, using small scale efforts, over 10% of the contaminated land around Chernobyl has been reclaimed. Mostly through the use of phytoremediation (use plants that naturally decontaminate). Over half of the pre-incident population still lives ther and a large part of the land initially effected has radiation levels that have naturally decreased to the levels needed for producing clean (i.e. radiation free) food, water, and livestock.
"According to the Nuclear Energy Agency (a specialized agency within the Organization for Economic Co-operation and Development, an intergovernmental organization of industrialized countries based in Paris) only 31 persons as of April 2001 had died as a direct consequence of the accident. They were all either plant personnel or directly involved in fighting the fire following the explosion. Another 140 individuals from these same groups suffered varying degrees of radiation sickness and health impairment, but all had recovered fully with no permanent consequences. During the period between 1990 and 1998, in the regions affected by the explosion and subsequent fallout, officials diagnosed 1,791 cases of thyroid cancer that were assumed to have been caused by the radiation release."
-- Robert G. Williscroft of DefenceWatch.
And that's the worst real life actual event for nuclear energy. An event that is physically impossible in American reactor design.
Fact is we, the US, have decades of safe use of nuclear power reactors. Other countries have it as well. Once you get past the hype, you get enlightened.
Anyone who beleives nuclear is this horrible uncontainable monster has been brainwashed by lunatics and anti-reality scaremongers.
Mods: the parent post is not only insightful, it is incorrect. Please act accordingly.
My Suburban burns less gasoline than your Prius.
I think the fact that its barely above absolute zero, as well as the fact that hydrogen is tiny. You just won't believe how vastly, hugely, mind-bogglingly tiny it is. I mean, you may think it's a long way down to the size of a transistor in your processor, but that's just peanuts to hydrogen.