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Sierra Lobo to Test New Liquid Hydrogen Storage System in Hydrogen-Fueled Silverado
19 June 2008
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| The Sierra Lobo liquid hydrogen storage system (vacuum jacket not shown). Click to enlarge. |
Sierra Lobo will test its No-Vent Liquid Hydrogen Storage and Delivery System, currently under development under contract with the Department of Defense (DOD), in a custom Hydrogen Internal Combustion Engine (HICE) Silverado truck provided by Electric Transportation Engineering Corporation (eTec) (earlier post).
The No-Vent system, specifically developed to eliminate hydrogen boil-off in ground and space transportation systems, is derived from liquid hydrogen (LH2) storage system technologies originally developed under several Department of Defense contracts that Sierra Lobo is now integrating for dual-use (military and commercial) hydrogen vehicle applications.
The No-Vent system cools the storage tank walls and intercepts environmental heat leak before it reaches the liquid, thus providing for the storage and dispensing of liquid hydrogen without venting.
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| Operating conditions of the Sierra Lobo high-efficiency Pulse Tube Cryocooler. Click to enlarge. |
The system that will be integrated into the HICE Silverado consists of a 10 kg liquid hydrogen, super-insulated tank with a nominal operating pressure of 550 kPa (80 psia), an active-cooling loop around the tank, a low-pressure, drop cooling loop helium circulation blower, and the Sierra Lobo two-stage pulse tube cryocooler driven by a long-life linear compressor. The active-cooling loop is connected to the pulse tube cryocooler at the 2nd stage cold heat exchanger, which operates at 20 K (-253°C).
In an article for the newsletter of the Ground Testing Committee of the American Institute of Aeronautics and Astronautics (AIAA), Sierra Lobo said that the pulse tube cryocooler is the key component to this active-cooling system.
The pulse tube cryocooler is capable of lifting 4 W at 20 K, at the second stage, and can simultaneously lift about the same wattage at 80 K, on the first stage. The cooling capacity of the first stage will be used for cooling thermal shields that will further minimize heat leak into the hydrogen tank.
Approximately 600 W of electrical input power will be required to drive the compressor. This input power will be provided by off-board facility power or plug power when the vehicle is parked. Heat will be rejected at the aftercooler flange at 300 K using the vehicle on-board water cooling system.
The pulse tube cryocooler was designed and built by Sierra Lobo and is the most efficient hydrogen cryocooler of its size in the world at 12 percent of Carnot.
The No-Vent Liquid Hydrogen Storage and Delivery System will be mounted in the bed of the Silverado and will take up one third of the space that a comparable compressed-gas storage system would occupy.
While eTec currently has several HICE vehicles that are powered by compressed hydrogen in operation throughout North America, the eTec HICE Silverado delivered to Sierra Lobo, Inc. will be the first eTec HICE vehicle to be powered using liquefied hydrogen (LH2) technology.
With technical assistance from project partner, Roush Industries, eTec led the conversion of the eTec HICE Silverado. Based on the full-size 2007 Chevrolet Silverado 1500 HD pickup truck utilizing the Vortec 6.0 Liter V8 engine, the vehicle was customized to Sierra Lobo’s specification and underwent internal modifications to meet the technical demands and requirements needed to run on a liquefied hydrogen fuel system.
The eTec HICE Silverado is the only production HICE vehicle participating in the Department of Energy’s Advanced Vehicle Testing Activity under the FreedomCar and Vehicle Technologies Program.
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June 19, 2008 in Engines, Hydrogen, Hydrogen Storage | Permalink | Comments (29) | TrackBack (0)
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Comments
Definatey wont see this on a jet ski anytime soon.
When electronics became integrated to motor vehicles,
a large percentge of motor mechanics left the buisness.
Nowdays a lot all themselves technicians, What willthe next generation call thelvebA
Posted by: | Jun 19, 2008 3:25:11 PM
themselves?
oops!
Posted by: arnold | Jun 19, 2008 3:26:24 PM
Does anyone else besides me see this as horribly inefficient? How about terribly expensive? Anyone?
Posted by: GreenPlease | Jun 19, 2008 3:27:32 PM
It's like some kind of rube goldberg fuel storage system! What happens when two cars collide? Does one of them "freeze" the other one when the LH2 leaks out? How much energy is required to make 1 Kg of liquid H2? Watts to wheels efficiency is down a lot for hydro-splitting -> H2 gas -> LH2 compression -> transportation to fueling station -> pump into tank.
Posted by: | Jun 19, 2008 4:25:44 PM
To the hydrogen developers, efficiency is not a development concern. In fact, they can ask for more federal subsidies when the process is less efficient at the start. At the same time, natural gas prices can be boosted to very profitable levels for them. This is a win/win scenario for them.
Posted by: Lulu | Jun 19, 2008 4:30:45 PM
The first stage alone could work nicely in conjunction with a LNG tank.
Posted by: Paul F. Dietz | Jun 19, 2008 4:39:48 PM
"The system that will be integrated into the HICE Silverado consists of a 10 kg liquid hydrogen, super-insulated tank with a nominal operating pressure of 550 kPa (80 psia), an active-cooling loop around the tank, a low-pressure, drop cooling loop helium circulation blower, and the Sierra Lobo two-stage pulse tube cryocooler driven by a long-life linear compressor. The active-cooling loop is connected to the pulse tube cryocooler at the 2nd stage cold heat exchanger, which operates at 20 K (-253°C)."
OR, and I know this is radical idea, but you could also have a solid state battery that stores electricity that has no moving parts at all, nor any parts at 20K.
Posted by: | Jun 19, 2008 5:01:29 PM
Let's see, 600 W * 22 hr/day = 13.2 kWh/day
13.2 kWh/day / 250 Wh/mi = 52.8 miles/day
So the electricity required just to keep the fuel from boiling away from this thing would run a bigger-than-Tesla electric vehicle more than 50 miles per day.
The people responsible for this DoD contract should be sacked.
Posted by: Engineer-Poet | Jun 19, 2008 5:25:20 PM
Ha ha, they won't get fired. The federal appointees from the oil industry will give them full funding. You guys are doing a "hecka job", etc.
Posted by: Lulu | Jun 19, 2008 6:10:11 PM
Wow .. this uses Liquid Hydrogen, Liquid nitrogen, extra power if you DON'T drive, and keeps the "Big-Oil" boys firmly in charge. . .
Goin' down that long H2 highway ...
Send in the klowns.
Posted by: J T | Jun 19, 2008 8:37:39 PM
No-vent LH2 system makes little sense, even for the military, when it consumes 600w of power all the time. In the field, it's no good, since where does the electricity come from to power the refrigerator? At base or camp, it's not of much use, since one can always fill-up the LH2 tank prior to use and save the base or camp electrical grid from additional electrical load.
Just use a regular LH2 tank and feed the vented H2 to the engine to produce electricity to feed to the grid where the vehicle is parked, resulting in no wasted energy. Far more practical in the field would be a recently featured 5000psi LH2 tank that can keep a full tank for 6 days without venting, and it can keep 1/3 of maximum H2 capacity for an indefinite period of time.
However, small-size H2 liquifiers like this would be valuable for a military camp or base to produce and liquifying its own LH2 fuel in the field from wind or solar electricity...hence greatly simplifying the logistic of having to transport flammable fuel in convoys that would be very dangerous in an ambush. For a much larger LH2 reservoir than this 10 kg tank, like a 1,000-kg or 10,000-kg tank, the surface area to volume will be much lower, hence LH2 can be stored using far less power per unit of mass than in this 10-kg tank, justifying the logistic of LH2 in the battlefield.
Imagine Gen. Rommel in WWII having this kind of modern-day LH2 fuel supply system...
Posted by: Roger Pham | Jun 19, 2008 10:21:19 PM
"How much energy is required to make 1 Kg of liquid H2?"
Round about 1/3 of the lower heating value.
Posted by: randomdude | Jun 19, 2008 10:23:17 PM
For the military it makes perfect sense as it allows them to put a uav aloft with a 500 kg tank of fuel and get 19 MEGWATT HOURS out of it.. minus a little MINOR power draw to keep it all cool. Thats moew then enough fuel to power a laser cannon and fuel the plane and electronics.
Posted by: wintermane | Jun 19, 2008 10:33:59 PM
Its late Wednesday evening at Sierra Lobo and the guys are tired. It was a long day and they’d all had a little too much beer.
Bill: Man, we gotta get even with them knuckheads at Ballard Power Systems. They sold busses to the Santa Clara Valley TA that cost 32 times as much to run as a diesel. 32 times for crisakes! Our LH system can’t touch that.
Larry: OK how about we say we will use only 80 psi?
Al: What? Lower pressure is cheaper.
Bill: No. No, that means you need expensive insulation to reduce the boil off.
Joe: How expensive can that be – Oh, wait lets put a refrigerator in to eliminate boil off. Hoo Ha
Larry: That’s great; We’ll use an active-cooling loop around the tank, and the Sierra Lobo two-stage pulse tube cryocooler. Even the military said “Are you nuts? Even we can’t afford that thing.”
Al: But won’t the pulse tube cryocooler add some credibility.
Joe: Ohhh, gasp, I can’t laugh and talk. NO, that thing may be the best in the world –but do you know what that means? 12 % HaHaHaH
Larry: We can’t stop there; let’s add a helium, cooling loop circulation blower.
Al; OK - do you realize that we not only have the initial cost so high Kuwait can’t afford it but the cryocooler uses as much energy parked as a diesel truck does when it’s moving?
Bill: Write this up and give it to Cheryl. As soon as she finishes those press releases tomorrow we’ll ask her to help polish it up. We’ll send it to Ballard Power Systems. We’ll tell ‘em we have a buyer. They’ll get a hoot out of it.
Posted by: TopaTom | Jun 19, 2008 11:28:53 PM
it makes sense for an UAV to stay parked at 70,000 ft, with that 500kg tank and solar cells.. also the cooler should be more effective at that altitude since it is colder.
Posted by: Herm | Jun 19, 2008 11:33:48 PM
Don't they USE the boil off to stay at 70,009 ft ?
Posted by: toppaTom | Jun 19, 2008 11:39:58 PM
The main European promoter of hydrogen fuel cells was a scientist who remembered how to do arithmetic and could not work out any way to have hydrogen fuel cells work in cars. So he is promoting something else. Electric cars are far more efficient; ZEBRA batteries need to be kept hot, but they require far less power and only simple resistive heating, and they will not blow up if power fails. The electrical energy in the TH!NK ZEBRA battery could be used to keep it hot for (26000/2400) more than ten days. This would be more than enough time to get to a plug to recharge and does not consider the heat energy available as well.
Electric cars must all be required to be series hybrids with at least a small emergency charging engine generator, so that they can be filled at any gas-station. Ethanol would be the clean fuel of choice, but the use of gasoline in emergencies should be provided for.
Petroleum companies diverted funds away from one researcher who, thirty years ago, promoted methanol from coal as the future locally produced car fuel.
Liquid hydrogen may well be the best fuel for unmanned military aircraft, as it works very well for rockets, but fuel cells are too heavy. But you will have a machine on the ground that will convert diesel to liquid hydrogen with large energy losses.
It would take less space and be cheaper and easier to run a car engine that sequestered CO2 and H2O than the current fuel cells do.
Modern car diesels already have nearly the efficiency of fuel cells and can be run in a combined cycle for even more efficiency.
Posted by: Henry Gibson | Jun 20, 2008 12:12:33 AM
Even in aircraft and rockets, liquid hydrogen is oversold. The problem is its low density. A rocket stage using hydrocarbon fuel will need to have a higher mass ratio to achieve the same velocity at burnout -- but it can achieve the higher mass ratio, since propellant tank mass scales as volume, and rocket engines using dense propellants need smaller and less powerful pumps (since pump power goes as pressure x volume/time), and hence are lighter.
The Lockheed 'skunkworks' worked a few decades ago on a groundbreaking LH2 fueled spyplane called Suntan. They could never get the design to close, since the propellant tanks were so bulky. In commercial aircraft, the fuel would be far too bulky to fit in the wings; large propellant tanks in the fuselage or in a blended body/wing design would be needed. The same problem affects LNG aircraft, if not to the same extent.
The NASP (National Aerospace Plane) foundered in part because of the huge LH2 tanks it would require. Airbreathing hypersonic launchers are probably unworkable in no small part because trading less LOX for more LH2 is a losing game.
There are two main expendable rockets available in the US today, the Delta 4 and Atlas 5. The Atlas, which uses hydrocarbon fuel, is more economical.
Proper use of LH2 in rockets is probably limited to upper stages. The first stage does not benefit much from the higher Isp, so the cheaper and denser hydrocarbon fuels should be prefered. For reusable upper stages that stay in space, refueling in space, preferably from hydrogen derived from materials in space, is probably the way to go long term. For that, you want to be able to store LH2 in space at a depot, and for that, this kind of refrigeration system would be quite useful.
Posted by: Paul F. Dietz | Jun 20, 2008 4:32:10 AM
There's also another danger using liquid hydrogen: it is EXTREMELY explosive.
Imagine if you're driving a vehicle fuelled from an LH2 tank and you get into an accident--if the LH2 tank even has a very tiny leak it will literally become a powerful bomb.
Posted by: Raymond | Jun 20, 2008 4:53:01 AM
The pulse tube cryocooler is capable of lifting 4 W at 20 K, at the second stage,...
Approximately 600 W of electrical input power will be required to drive the compressor...
Heat will be rejected at the aftercooler flange at 300 K using the vehicle on-board water cooling system.
So the cooling efficiency is 1/150... :-(
And this is 12% of the Carnot theoretical limit ? Hmm, let's do the maths : 1/((300/20)-1) = 1/14, this is Carnot. So we end up with less than 10% if the figures are right.
Let's summarize :
- cooling is TERRIBLY inefficient even in the ideal case because of thermodynamics, when the cold temperature is extremely cold ;
- adding reality gives you another terrible factor.
If this was supposed to demonstrate the nonsense of such a test, it has been achieved beyond any expectation.
Posted by: François | Jun 20, 2008 5:00:39 AM
Am I the only one to notice that the 600W is the nominal power of the cooler, which will probably switch on only if the temperature rises, like a refrigerator. I think it is not true, as some suggest, that it needs a 600W to keep the H2 liquid.
@wintermane:
Whether it makes sense depends on how much boil off you prevent. It is no use adding a 10 kg compressor to prevent a boil off of 5 kg H2.
Posted by: Anne | Jun 20, 2008 5:35:19 AM
@ Henry Gibson ~> "Electric cars must all be required to be series hybrids with at least a small emergency charging engine generator, so that they can be filled at any gas-station."
That sort of plan keeps everyone tied to the old dirty liquid fuel market that is causing global warming, inner city pollution and high costs.
Actually there is another option. A far better option.
Placing "pay-for-plugs" in all major shopping centers, theaters, restaurants etc, lets drivers recharge while getting lunch, using a rest room, or while shopping. This "destination-recharge" ability makes Electric cars into first choice transportation.
Posted by: John Taylor | Jun 20, 2008 6:44:20 AM
Have to agree with JT here. We need to get away from this one vehicle fits all paradigm(8 passenger 4WD SUVs, and extended cab pickups come to mind.) Small all-electric cars (even with limited range) would suit most people's daily commuting needs. PHEV's, HEVs and diesels could provide for the rest of our needs.
Posted by: Bob Bastard | Jun 20, 2008 7:16:25 AM
Is this one of the craziest things you ever did see?
Use bio diesel or some other form of energy. This is a technology desperately looking for a purpose.
Did the taxpayers spend money to make this?
Posted by: BobT | Jun 20, 2008 7:34:02 AM
A LH2 tank is not explosive at all !.
the boiling of liquid H2 is an ENDOTHERMIC process, thus it will certainly not be an explosive event. very fast, it will freeze its surroundings, and then the rest becomes vapor rather slowly. The gaseous H2 off course is flamable, but not more than natural gas. BUT, since gaseous H2 is very light, it will rise to the stratosphere very quickly, making a real big explosion relatively unprobable, compared to natural gas, which is relative heavy. A big leak of natural gas can lead to very very very big explosions if there is no wind and the detonation occurs hours after the leak is created. with hydrogen, there would never be a big build-up to cause such explosions.
A natural gas leak will crawl over the surface until it encounters a spark...boom
A hydrogen gas leak will immediately go to the skies, making a detonation unprobable.
Posted by: Alain | Jun 20, 2008 7:58:42 AM
The Hydrogen Emperor has no clothes.
(Hasn't somebody said this yet?)
Criminally stupid waste of research dollars. Shouldn't the DOD be spending this money on more flak jackets or bomb-proof Hum Vees?
If you simply have to use a cryogenic, synthetic, liquid fuel, then use liquefied methane. Much easier to handle and more energy dense (even when using an ICE over a fuel cell; it's STILL a denser fuel.) Methane can be produced synthetically from hydrogen by reacting H2 with CO2 in a Sabatier reactor.
Posted by: Jim | Jun 20, 2008 9:36:45 AM
THanks, Anne, for the astute observation that the 600W compressor will only run intermittently.
However, even if it only runs 1/2 of the time, 300 W of power consumption 24/7 will still be too much of wasted energy.
But the bigger problem for widespread deployment of LH2 is the use of helium as refrigerant, since LH2 is so cold that no other substance (?) will stay at gaseous state at the condensation temperature of H2. Helium is in very limited supply.
Posted by: Roger Pham | Jun 20, 2008 1:21:38 PM
We don't know the duty cycle of the chiller because we haven't been told the heat leakage rate into the tank. However, it wouldn't make much sense to oversize the cooler by much; it's not needed when the engine is running [1] and overcooling the tank wouldn't help all that much.
[1] When H2 is being drawn, the tank is chilled by boil-off and the LN2-temp heat shield can be cooled to nearly LH2 temps using the off-gas.
Posted by: Engineer-Poet | Jun 21, 2008 8:14:14 PM
I hope they have a relief valve on this contraption in case of an electrical power failure.
Or am I missing something?
Posted by: Mannstein | Aug 6, 2008 7:38:33 PM
