Questions about a Hydrogen Economy; Scientific American

In summary, The conversation discussed the potential of a "hydrogen economy" and the role of hydrogen as an energy carrier. While there are concerns about the energy cost of producing hydrogen, there are various approaches and resources being explored to make it a viable option. The article mentioned in the Science American magazine provides a snapshot of the current state-of-the-art and there are ongoing initiatives and discussions about the use of hydrogen as an energy source. It is seen as a potential solution to our dependence on fossil fuels.
  • #351
President George W. Bush has talked of a hydrogen economy, in which abundant energy would be extracted from water and the tailpipes of cars would be clean. But extracting hydrogen from water requires energy -- fossil fuels or nuclear power, for example.
How much hydrogen could be produced by a Large (1MW) wind turbine in a year??
 
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  • #352
One can find some information here.

Hydrogen Fuel Cells and Infrastructure Technology.
http://www.eere.energy.gov/hydrogenandfuelcells/analysis/cost.html

Technological Feasibility and Cost Analysis
http://www.nrel.gov/docs/fy04osti/36734.pdf

Based on 3.1557 E7 sec/yr and 1 E6 J/s = 3.1557 E13 J/yr (for 1 MW windmill),

and simply using heat of formation of water - 285.83 kJ/mol,

then one obtains about 1.1E8 gmoles of H2 or 2.2 E8 g/H2 per year, but that assumes 100% efficiency.

For some bascis on electrolysis and fuel cells, see - http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/electrol.html#c1

The numbers from DOE's Energy Efficiency and Renewable Energy (EERE) are more realistic.
 
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  • #353
220,000 kg of hydrogen from one wind turbine , thanks.. :smile:
 
  • #354
willib said:
220,000 kg of hydrogen from one wind turbine , thanks.. :smile:
It will most likely be less than that depending on the efficiency of the electrolytic cell. I assumed ideal conditions, not accounting for recombination and other effects.

The EERE reports should give better information.
 
  • #355
Astronuc said:
It will most likely be less than that depending on the efficiency of the electrolytic cell. I assumed ideal conditions, not accounting for recombination and other effects.

The EERE reports should give better information.
i understand , i was looking for a ballpark figure.. :smile:
Thats a lot of Hydrogen , no ?
 
  • #356
The chicken and egg problem

Note that there may be partial solutions to two key challenges to a hydrogen economy.

First of all, biofuels from algae appears to offer an efficient and practical solution to solar energy conversion. In effect, by farming algae for the production of biofuels, one grows the solar collector. Test crops have produced the fuel equivalent of about 925KW-Hrs per acre-day. Also, whereas alternate sources of biodiesel feedstock typically result in a return on invested energy of a little more than 300%, algae developers are claiming returns of up to 1000%.

Next, it occurs to me that the use of algae for biofuels - in particular, for biodiesel - offers a partial solution to what is known as the "chicken and egg problem" of a hydrogen economy. Since algae can be farmed for the production of biodiesel, an immediate economic justification and motive to farm algae exists. This is presently an infant industry. The biodiesel industry itself is growing quickly with many sources of feedstock including used cooking oil, and raw canola, soybean, palm, and rapeseed oil, to name a few.

As demand for hydrogen comes into play, since algae can be used to produce biodiesel, ethanol, or hydrogen, algae farms geered towards biodiesel production could likely convert to an algae that is well suited for hydrogen production. Much of the farming and processing requirements remain a constant.

In effect, we may have our source of hydrogen as well as a transition technology.
 
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  • #357
You read my mind, Ivan. That is exactly the series of events I'm hoping to see happen. (I'm currently attending college with an eye towards working in the "alternative fools" industry.)
 
  • #358
Cool! :approve:

I hope to be knee deep in pond scum in a couple of years.

The yeild per acre per day for farmed algae is mind boggling. Even with a three-acre test plot, I should expect a little less than a ton of dry algae per day. [eh, more like 1300 Lbs]. This then should yield no less than 40% as much oil.
 
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  • #359
Just caught this in the news.

BMW is the only major carmaker to bring a car with a hydrogen-combustion engine beyond the prototype stage.

The automaker's approach is markedly different than the more familiar concept of hydrogen-powered fuel cells, where energy is stored before it is converted into electricity. By contrast, BMW's Hydrogen 7 is powered by pumping hydrogen into a combustion engine and igniting it. The engine can burn both hydrogen and gasoline, and switches between the two at the flick of a switch.

Burning hydrogen is more efficient than converting it into electricity, making it the more practical choice for hydrogen-fueled cars now, according to BMW.[continued]
http://www.wired.com/news/technology/autotech/0,72100-0.html?tw=wn_index_1
 
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  • #360
Burning hydrogen is more efficient than converting it into electricity, making it the more practical choice for hydrogen-fueled cars now, according to BMW

I'm prety sure they're just flat-out wrong about that one. Fuel cells are much more efficient than internal combustion.
 
  • #361
I'm not sure what the basis is for their claim, but I imagine that they are talking about the hidden energy costs in the materials used and the construction of fuel cells. Presumably this hidden energy is indirectly related to price. I just checked and found a price of about $10,000 per KW for hydrogen fuel cell stacks. http://www.fuelcellstore.com/cgi-bin/fuelweb/view=Item/cat=31/product=869

The BMW is rated at 260HP which is about 194KW.

How much of the relatively high cost of fuel cells is ultimately representative of the hidden energy of production? Also, what is the lifetime of the fuel cells and how are they recycled?
 
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  • #362
The world's hydrogen fueling stations
http://www.fuelcells.org/info/charts/h2fuelingstations.pdf
 
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  • #363
First Analysis of the Water Requirements of a Hydrogen Economy

...Each of the energy choices we can make, in terms of fuels and technologies, has its own tradeoffs associated with it,” Webber said. “Hydrogen, just like ethanol, wind, solar, or other alternative choices, has many merits, but also has some important impacts to keep in mind, as this paper tries to suggest. I would encourage the continuation of research into hydrogen production as part of a comprehensive basket of approaches that are considered for managing the transition into the green energy era. But, because of some of the unexpected impacts—for example on water resources—it seems premature to determine that hydrogen is the answer we should pursue at the exclusion of other options.” [continued]
http://www.physorg.com/news111926048.html

The point missed is that electrolysis is likely not the path to a hydrogen economy.
 
  • #364
And why can't we use seawater?
 
  • #365
Yes, seawater is plenty enough. edit: Perhaps the salt concentrations are too high and the resulting in maintenance issues make it cost prohibitive?

Also, I was thinking that this is a legitimate concern if using hydrogen from biomass that derives its hydrogen from fresh water. So, given that fresh water resources will grow [and are quickly growing] increasingly valuable, saltwater based biomass may be the best option for sourcing hydrogen; and for ethanol or biodiesel that is for distributed use, for that matter. In closed systems the water can be recovered after combustion.
 
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  • #366
Woohoo! Today when I proposed a hydrogen powered system as a solution to a unique industrial problem, by the time that the owners realized that I was serious and that we really can do this, they were bouncing off the walls.

Yay! I get to design my first hydrogen powered system.
 
  • #367
The hydrogen economy is the goal. The cheapest source of the energy to produce hydrogen from water is nuclear. Some engineer should be trying to figure out how to crack water from the heat generated by this energy source. Electrical generation of H2 and back to mechanical energy is use is too inefficient. The problem with H2 is it carries too little energy per unit wt.

Until this can be solved, we should be looking to make methane from hydrogen and CO2 with the energy from the nuclear energy source.

One idea that nobody seems to mention is getting rid of nuclear waste by jettison to the sun. I know we entered a treaty to ban delivery to the moon, but the sun certainly won't suffer.
 

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