Whydrogen = why hydrogen?

<div class='quotetop'>QUOTE(hyo silver @ Sep 21 2007, 11:38 PM) [snapback]516092[/snapback]</div>

Fuel Cells aren't a farce. That's a bit much. I agree that in vehicular applications they face some VERY difficult challenges, however, those are not the only applications of fuel cells. Stationary power generation is an area where Fuel Cells are already proving their worth in real world applications. They are more efficient than turbine systems at creating electricity and can consume a wide variety of hydrogen rich feed stocks (methane, gasoline, ethanol, diesel, ...) The best part is that they don't require exotic storage/delivery systems to work well.

 

<div class='quotetop'>QUOTE(tripp @ Sep 24 2007, 04:07 PM) [snapback]517026[/snapback]</div>

I think fuel cells shouldn't be the focus here. Let's focus on the fact that hydrogen is not an energy source . There are no hydrogen mines. Hydrogen is merely a very inneficient means of storing and transporting energy.

I believe the "Hydrogen Dream" is an obfuscation program by the energy industry to distract progresively minded folks from focusing on alternative energy production. Let's stop those lies!

 

Why hydrogen?? Because it is 'green'. Really, I agree, hydrogen is a farce, and quite a ridiculous one. I do wonder if hydrogen as an energy storage system doesn't hold promise - could it be used as a means to even out electricity power from wind and solar sources so that there is a reliable base energy supply?? For clarification, when the wind is blowing and the sun shining, electrolysis could split water to produce hydrogen and oxygen, and when the sky is calm and cloudy, the hydrogen can be burned back into water and produce energy. It wouldn't be efficient or cheap (as is), but it might be a solution to solving the uneaviness of supply of renewable energy sources.

 

Hydrogen is strictly an energy transport medium, as is electricity. The only 'why' to it is as a competitor to batteries for energy storage. I think a high pressure composite tank of hydrogen still beats the best batteries for energy density by an awful lot. A tank of hydrogen is a much simpler energy storage medium than any battery I know of, and I could easily see batteries never outpacing materials technology (safe tank pressure) to the point that changes.

But hydrogen is not an energy source, just as electricity is not an energy source.

 

Wow. Some great responses all over the map. I think we can safely assume that hyo's original comment was in regard to H2 FC's as a vehicle energy carrier/source. And I think most here agree that the whole idea of FCV's as a viable propulsion alternative to technology we had 10 years ago... is a farce.

<div class='quotetop'>QUOTE(tripp @ Sep 24 2007, 01:07 PM) [snapback]517026[/snapback]</div>

Right-o. Fuel Cells have their place. In the family sedan is not currently one of them.

<div class='quotetop'>QUOTE(MarkMN @ Sep 24 2007, 01:37 PM) [snapback]517050[/snapback]</div>

This is sort of like saying that lifting a brick over your head is "green." You drop it and you can recover energy from it. And I guess in a sense you could think of these things as "green" but it doesn't make all that much sense! You use H2, or the brick, to store energy. How GREEN the energy is, is totally determined by how it was produced, not how it was stored. If you produce X amount of energy, but can only store/reuse X/4 of that energy, then you've certainly lost some green points no matter how it was produced.

<div class='quotetop'>QUOTE(jweale @ Sep 24 2007, 01:53 PM) [snapback]517059[/snapback]</div>

Uh... yes, but that isn't the point. You can make H2 really dense. But at a HUGE efficiency cost. You must take into consideration ALL of the energy inputs into the storage system. If you charge a battery and lose 10% of the energy to heat, you have storage of 90% of your energy. If you try to shove H2 into a high pressure tank, you will lose 25%... 50%... and more (depending on what pressure you shoot for) of your original energy in the effort of compressing the gas to this wonderul "energy denseness." Yes, you can store H2 more densely... but at what energy cost?

Storing H2 in tanks is about as efficient to pump water up a hill and letting it run down later. And that's lots cheaper and more reliable than dealing with H2.

 

Greenkeeper is right in that H2 is not an energy source, but a storage medium.

The only real problem with H2 now is that it costs more in energy to produce than it outs outs when used. However, when used H2 is completely pollution free. (unless you consider water a pollutant)

I think that soon H2 production will be cheaper, just as Aluminium used to be more valuable than gold! until a new process was discovered for refinement.

A combination of battery tech improvement and H2 hybrids offer the best chance for a pollution free weengin from fossil fuels.

Heck, even now you could produce H2 from only green sources if you wanted too. I think wave and solr powered supertankers at see would make the best production facilities. Plenty of raw materials and free energy and away from popullation centers!

 

<div class='quotetop'>QUOTE(darelldd @ Sep 24 2007, 05:10 PM) [snapback]517065[/snapback]</div>

The pressurization work could be partially recovered when the gas is expanded with a simple turbine, but there is certainly loss compressing gas. I'm drawing my efficiency box around the mobile vehicle, with an eye to maximizing range or minimizing weight. There, savings would come from the reduced weight being carried about. On the global scale, hydrogen storage might also have a much lower embodied energy than batteries, depending on just how much platinum the mythical PEM fuel cell ends up containing.

In my current thinking, the global efficiency is a moot point when talking massive hydrogen use. Hydrogen only really makes sense if electricity become 'too cheap to meter' through some real future-future advance - fusion, orbital solar, paint on nano solar cells, genetically modified algae, etc. If hydrogen can be mass produced economically after the CH4 runs out, I bet that paying Mr Entropy when crunching it down will be a small price to optimize transportation range.

I can imagine hydrogen powered passenger jets (not dirigibles!) before I die, but battery* powered? (OK, alcohol is the obvious replacement for JET-A but the tenuous point stands)

*I'm not considering a fuel cell to be a battery, although a good argument can be made that it is.

 

I do not know about fuel cells, but there was a special on the Weather Channel about environmental advances. There was some guy who had a solar farm at his house. He had 2 acres of land so on one section he had enough solar panels to run his house and make hydrogen which was stored in 10 large propane looking tanks (each one the size of a car). That was supposedly enough energy for his house for the year. He used it at night or when the solar panels dropped in production and to power his car. He is an engineer and converted his car to hydrogen. I do not recall what the range was. His investment was $500k but I am sure the price drops as more are built.

He opened up one tank and it sounded like a balloon deflating. Although under pressure he said it was not anymore dangerous than having propane tanks there instead, if not safer.

If one guy could do that I think there are a lot of places which could do the same. Not enough to replace coal or oil but enough to reduce our dependence.

No it may not be the most efficient but it is the easiest for power storage. We do not have the technology to store a year's worth of power in batteries yet and you do not have to worry about replacing cells after so many charges.

 

<div class='quotetop'>QUOTE(hyo silver @ Sep 24 2007, 05:10 PM) [snapback]517118[/snapback]</div>

Yes. However, if Hydrogen were a cheap way to store excess energy (that would otherwise be lost) then it would be worth it. Right now that's a rather big if.

The waste heat from Solid Oxide Fuel Cells (SOFCs) could be used to heat water to steam and drive a turbine. The waste heat from that process could be used to heat water for domestic use or space heating. SOFCs run HOT, wicked HOT (800C or higher). I think the molten carbonate cells are hotter still. For home use, you're probably right, though Honda has been playing around with a home fuel cell (SOFC I think) have powers the house off of NG. The excess heat is used for water heating and perhaps space heating (don't know about that part). This process would (I think) be considerably more efficient than have electricity and NG delivered to the house in the traditional fashion assuming a typical electricity source.

It seems like pyrolysis of biomass would be a lot cheaper than a new hydrogen infrastructure. Of course the hydrogen would be cleaner at the point of use.

 

<div class='quotetop'>QUOTE(hyo silver @ Sep 24 2007, 07:10 PM) [snapback]517118[/snapback]</div>

Geothermal heat pumps run into problems in unbalanced climates. They don't really pull much heat out of the ground, rather they let you store heat in the summer and draw it out in the winter. Unless you have high water movement, you have to put about as many btus in as you pull out or your loop temperatures (and heating COP) slowly drop over the years. It is easiest to think of a geothermal heat pump as a huge thermal storage tank that lets you average out the annual temperature. If your annual temperature is something like 40F, it's not gonna do the job (homes get around this by using electric resistance supplemental heaters when required).

As far as money goes, the little natural gas fired Capstone turbines can pay back in commercial buildings (I spec'd one for a lab in Nevada with high makeup air heat loads recently). In CA, 1 kWh of electricity is assumed to cost 3 kWh of natural gas to generate and get to the site. So, if you can burn 3 kWh of natural gas to get 1 kWh of electricity (33% efficiency), any waste heat you recover is all gravy.

The PAFC fuel cell option currently commercially 'available' is sexy, but not really economical. Actual fuel cells available commercially today use natural gas as the feedstock, not straight H2. The microturbines or even optimized V-8s are where things are actually happening.

 

<div class='quotetop'>QUOTE(Tadashi @ Sep 24 2007, 06:51 PM) [snapback]517204[/snapback]</div>

Easiest? Not by any metric I'm aware of. Pretty far from the easiest. Very far from the most efficient. And even farther from the cheapest.

I'm not sure what "a years's worth of power" really means here. How long did it take him to make enough "power for a year" in H2 from his solar panels? If he were storing the energy in batteries, he'd only need 1/4 of the solar power from the PV array to begin with. And you don't need power for a year... you need enough to get you through the night, and to the next sunny day. Storing "enough for a year" is a big ol' waste of resources... and like I said, I'm not really sure what that means or how long it takes to create that much energy via the PV array. It takes me about a year to produce the power I need for a year... and that's used directly - with insignificant frictional losses.