US Navy Green Fuel - Liquid H2

[allardjd 1,853]

One of the US Navy's test UAVs is flying on cryogenic liquid hydrogen, doubling its endurance over an earlier compressed gaseous hydrogen fueled version of the same airframe.  This - liquid hydrogen - may be the fuel that takes us into the next century for transportation applications, i.e. things that must move and can't be attached to a wire. 

 

http://www.engadget.com/2013/05/10/us-navy-ion-tiger-drone-record-flight/

 

Hydrogen can be made easily by electrolysis of water, breaking it down into the components, oxygen and hydrogen. 

 

Cryogenic hydrogen makes a lot of sense as the fuel that may eventually replace oil for mobile applications.  Maybe it will and maybe it won't, but it's a contender and may just make the cut.  Most of the other renewable sources under consideration are ultimately some kind of bio-mass. 

 

Many of those alternative fuel sources (not all - e.g. algae) put energy production into competition with growing food, taking farmland out of food production and increasing the demand for farm labor, fertilizer, etc, all of which, if not resulting in actual scarcity, at least tends to drive up food prices.  In my opinion that competition between the production of energy and of food is not a great idea for the human race to proceed with.  Farmers may like it, but those who buy food probably will not be quite so ecstatic.

 

It's already happening with ethanol from corn.  The US alone produced almost 14 billion (yes, the "b" is correct) US gallons of ethanol from corn in 2011, at a rough equivalence of 25# of corn to one gallon of alcohol. That's about 175 million tons of corn that didn't make it to the food market, either directly or as livestock feed.

 

From the Navy perspective, one advantage will be the ability to produce aviation fuel at sea from seawater, using nuclear generated electricity to electrolyze water.  (Nuclear submarines have been doing that for decades on a much smaller scale to produce the oxygen the crew breathes.) That prospect of making jet fuel at sea could free the carrier groups from the oilers that currently must bring them the fuel needed by their air wings, even though the carrier needs no fuel replenishment for itself while under way.

 

John

[Quickmarch 488]

Also, we need to pay serious attention to another depleting resource - fresh water. How much water went into the production of the bio-fuels? Bio fuels are looking like a net loss product. Keeps the farm lobby happy at the expense of the rest of us.

 

Just my $0.02

 

Meanwhile, my boat (home) is steaming across the Pacific at 17-1/2 knots. Well over three times her normal progress. I'm going to have to relinquish my position as chief non-fossil fuel burning yachtie.

 

Cheers,

March - back in broadband land (Auckland)

[allardjd 1,853]

When do you fly to Canada, March? Must be coming up pretty soon.

John

[britfrog 180]

over the last 30 years there have been numerous companies , mostly in the US who have created a viable  hydogen solution for cars, however when it came to the production stage when they needed finance wall st was not forthcoming and the distribution also as that would affect the petroleum companies , so in the end everyone of these companies were bought out by the petroleum companies and closed down or stifled. IMHO there is no alternative to Hydrogen, there are no polluting by products so why doesnt common sense over rule the petroleum co's?

 

 

[Quickmarch 488]

@John - 15 th. We get back before we left, thus recovering the day we lost on the way down here. Makes me feel younger just thinking about it.

@Britfrog - see: http://en.wikipedia.org/wiki/Petrodollar

[ddavid 149]

Hydrogen - possibly the most dangerous gas? Remember the Hindenberg?

And what's the efficiency of producing H2 from nuclear power? I must admit, I wouldn't know where to start working that out - but how's about:

1. nuclear fuel makes heat,

2. heat makes steam,

3. steam drives turbine,

4. turbine drives generator,

5. generator produces electricity,

6. electricity electrolyses water,

7. gaseous hydrogen compressed to cryogenic fuel - possibly mechanical,

8. fuel kept cool - like 40 deg K, so forth.

And then you come back to Hydrogen storage and the dangers associated with it. Outside defense, it's a No-Brainer.

Cheers - Dai.

[britfrog 180]

I am afraid i disagree hydrogen is our future we cannot continue to polute the world as we are and it is getting far worse with china coming on line, there is no storage problem only a perceived problem harking back to a period when we kept it in cloth bags which were prone to leakage at the best of times. bearing in mind hydrogen has 3 times the calorific value of petrol we will only require petrol tanks 1/3 of the current size and it is simplicity itself to make a strong double or triple  skinned tank that size that is a lot safer than todays petrol tanks. Of course it doesnt get rid of the problem of global heating from internal combustion engines however we will never have a viable cheap car driven by batteries as long as we have a hole to speak from, the recent top gear did touch on a practical idea to some extent, with the idea from bumper cars, however with the new research into passing electricity without wires ie charging mobile devices without any kind of connection it is not beyond the imagination to have electric cables imbedded in the road surface or above like trams from where we will all get our power

time will tell

[Captain Caveman 0]

Hi all,

@Britfrog the possibility of running vehicles via electric cables under the road surface would be possible but how many government officials are getting under the table payments from petroleum companies to stop this from happening? It wouldn't take much engineering to get from this - www.amazon.co.uk/gp/feature.html?ie=UTF8&docId=1000449663 to the drive by electric wire idea. And on a side note would make battling crime in the far future easier ( cutting/reducing power to sections of the road to stop speeding vehicles/get away drivers)? All getting blade runner here I need to lay down in a dark room!

Glen

[allardjd 1,853]

@ Dai - your items 1 through 5 is a 32% cycle, just like all conventional cycle steam plants whether burning coal, oil, natural gas, wood, trash, soybean oil, whiskey, frankincense - or uranium. It's not as if there are other urgent needs for the uranium unless we're running out of bombs, in which case we could just as well extract the plutonium from the spent fuel, having our energy cake and eating it too.

 

Combined cycle plants can take the cycle efficiency up to about 42%, incorporating a large gas turbine and an additional electrical generator into the cycle as well as the steam turbine (not possible for nuclear). Some smallish ones have been built but are proving maintenance intensive except when natural gas fired. The difficulty is separating entrained solids from the hot gas stream to avoid blade erosion in the gas turbine. It's better with gas-fired units but the others have proven problematic, more or less, though the ~42% cycle efficiency is attractive.

 

Nuclear has the advantage of virtually zero greenhouse gas emissions as does the combustion of hydrogen. That would be a transport fuel cycle with essentially zero CO, CO2, NOX, SO2 burden - the greens ought to be turning - - - well, green with delight at the idea of that. Compare that to the emission of said products from our current transport technologies. A nuclear/hydrogen based transport cycle would eliminate ALL of that.

 

As for hydrogen and the Hindenburg, fuel is flammable - that's why they call it fuel. Gasoline, diesel and Jet A aren't the friendliest substances in the world either, but we somehow manage to produce, transport, store and consume enormous quantities of them every day without incinerating the general public. Yes, there are accidents with them from time to time, but it can normally be done with acceptable safety.

 

We used massive amounts of H2 at the plant for the 28 years I was there. Virtually every large electrical generator in the world is cooled by the circulation of gaseous H2 as a heat exchange medium because it has a good specific heat and very low density. We used it on the reactor side too, for system chemistry purposes, but in smaller amounts. It can and is handled safely every day, just as gasoline is.

 

The efficiency of electrolyzing water is relatively low, but oil's not exactly cheap either, is it, and it's not getting any cheaper.

 

Yes, mechanical compression to liquefy H2, probably at the source and in transit and at large-scale storage. I suspect that in the individual vehicles insulation and evaporation would play more of a role in maintaining the required low temperature. It's not rocket science.

 

I'm not saying this is THE answer, but it should be part of the solution set being considered. As a fuel, the feedstock is as plentiful as water - WAIT A MINUTE - it IS water. I find the idea of economically and physically separating our food sources from our energy sources highly attractive. Ecologically, the frosting on the cake is a transport cycle with no harmful emissions, THE solution, the proverbial free lunch.

 

John

[ddavid 149]

Thanks for that, John. I'm still not really happy about the electrolysis stage, but, as you say, if it works, use it. I guess that LNG technology can be used for H2 as well? 

 

My problem with storage and transportation is that most people are quite unaware of the dangers of petrol (and diesel) so who knows what might happen with H2...

 

Cheers - Dai.

 

[Quickmarch 488]

All this is assuming we HAVE a greenhouse gas problem. Some interesting reading here: http://members.shaw.ca/sch25/FOS/Climate_Change_Science.html

 

 

 

 

[allardjd 1,853]

 

I guess that LNG technology can be used for H2 as well?

 

 

As far as I know that's correct - I would guess the cryogenic aspects are similar, though temperatures and pressures might differ somewhat. Not that much different from propane either, except that does not need to be refrigerated to remain liquid.  Millions of back yard barbie users manage to use propane and damage no more than burgers and expensive steaks most days, despite the potential bomb sitting just below the burners.

 

As for the dangers, certainly there will be some, and some accidents.  There are morons out there who can injure themselves with a spoon.  Society can't protect all of them from themselves.  You can build a lot of supposedly fool-proof, fail-safe features into the hardware but in the final analysis, you can't fix stupid.

 

John

[GHAO 0]

I must add in here that hydrogen did not blow up the Hindenburg... for a start, hydrogen burns with no or a slight blue flame - and the pictures testify that there was a big flame. Secondly, they painted the Hindenburg silver... and silver paint has been for centuries a rather useful explosive, and recently components of it are used as fuel for spacecraft. There's other reasons I can't remember... but the short of it is don't paint your airship with rocket fuel.

 

With the Hindenburg the fire was not actually hot enough to ignite the hydrogen - although many people worry about safety of hydrogen cars and what happens when they crash, it is likely that any hydrogen in the car will just escape, unless it was pressurised - in that case you have a bomb on your hands, and Boston certainly knows what pressure cookers can do.

 

The main problem is making the hydrogen, and transporting it. It has to be supercooled before it can be transported, and the expense of that makes it necessary to produce it on-site. Which requires huge amounts of electricity, with here in the UK is almost certainly coal or gas. Our nuclear plants are closing down, we haven't built any for twenty years, and it'll take another 20 years to build any more. Wind power is just as expensive and somehow it is taboo for a lot of people. Solar power isn't very useful in the UK either! We don't have the natural resources for extensive tidal barrages or hydroelectric dams either. We have one good site for tidal power and it is off the books as 'the environmentalists might get upset'. So we have hydrogen made by fossil fuels...

 

If hydrogen promises so much, how come it's taken twenty years or so for it to go from cars to planes? There are seriously large hurdles first. Though I agree with you John, nuclear/hydrogen would be best for all of us (if there's enough uranium), but it's too late or too expensive for that to happen in the UK. France, maybe.

[allardjd 1,853]

Hydrogen burns with an orange flame - alcohol burns with a pale blue, almost invisible flame. In a proper burner with the correct ratio of air metered in, most any gas will burn with a mostly blue flame, but in open air, raw hydrogen burns orange.

 

The common component in silver paint and (solid) rocket fuel is aluminum powder.

 

Hydrogen can be transported safely either as a compressed gas or as a cryogenic liquid. If the compressed gas methodology is used it does not have to be cooled. I have first hand experience with tank-trucks of compressed hydrogen at, if memory serves, around 5,000 psi. It comes at ambient temperatures. It is not necessary to produce H2 at the site of usage - it can be transported in bulk either as a compressed gas or as a super-cold liquid, at much lower pressures.

By and large, the human race has always leaned most heavily on whatever source of energy is cheapest AND is available in sufficient quantity to meet current needs. That's still true today and probably will continue to be.

 

We use oil-based products for transport because it's the cheapest of the available alternatives and is still available in large quantity. H2 is not yet needed because the supply of oil is still sufficient, and, despite taxes adding significantly to the price, oil products are still cheaper than H2.

 

At some point, either growing environmental concerns or increasing scarcity of oil, or both, will make the use of H2 more attractive for mobile applications. For that to happen, there will have to be a source of electricity that is cheap enough to produce H2 at a cost that is at least equal to the cost of petroleum fuels for the same purpose. To the extent that concerns about environmental emissions come into play, that favors nuclear, either fission now or perhaps fusion at some point in the future.

 

In answer to why it has taken 20 years, the short answer is because it's still too expensive. The cost gradient between petroleum fuels and electrically produced hydrogen still favors oil. When that balance shifts, you'll see things changing quickly, I think.

 

As for domestic production, that's not any more necessary than it is for oil and natural gas. It may well be that one day instead of supertankers bringing oil to Britain as now, there will be LH2 tankers, looking much like the LNG tankers that are used today. The stuff can be made compact enough to shipped long distances by sea by liquifying it.

 

The primary barrier to H2 replacing petroleum products for mobile applications is cost.

 

John