Maybe the hydrogen economy will become reality some time...

Grisu Posted By Grisu, Nov 13, 2012 at 2:54 PM

  1. Grisu

    Grisu
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    As you may know I have been really skeptical about how much longer we can use non-renewable fuels to supply our energy needs. The current renewable energy sources (wind, solar, biomass etc.) are by far not efficient enough to take over once fossils fuels will get scarce. I was wondering whether it would be possible to directly generate hydrogen from water using sunlight and a catalyst. Looks like someone figured out a way:

    http://www.sciencemag.org/content/early/2012/11/07/science.1227775.full

    What is really encouraging is the high quantum yield of ~60% although they use only a narrow light spectrum of ~520 nm. Nevertheless, it is a good place to start.
     
  2. Beerdog

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    I don't think we have an argument, but I bristle when hydrogen is considered a fuel source, and I feel compelled to make the point that like fossil fuel, hydrogen (as created by the research cited) is another form of solar energy. The only energy sources we have on the planet are ultimately derived from our sun and the Earth's internal nuclear reactions. We can't get more energy out of a process than we put into it, so the energy yield of the hydrogen process is limited by the solar input. Ultimately, as our fossil fuels get scarcer and more precious, mankind will have to learn to live in a balanced energy budget.

    My perspective is that petroleum has far more value as a chemical feedstock for the synthetic materials than as a fuel. We are shortsightedly burning our chemical raw materials at the expense of future generations. Further, because of its energy density and relative safety, carbon based fuels are the only practical alternative for much of the transportation sector.

    John
     
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  3. Joe Rampey

    Joe Rampey
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    Really! are you concerned that we will exhaust the energy available from the sun?

    Averaged over the entire surface of the planet, 24 hours per day for a year, each square meter collects the approximate energy equivalent of almost a barrel of oil each year, or 4.2 kilowatt-hours of energy every day.

    quoted from: http://solar.gwu.edu/FAQ/solar_potential.html

    our problem today is harvesting it... and storing it - current photovoltaics are maximum 15 - 18% efficient. I welcome the above experiments - Put a few hydrogen generation farms in the arid region of Africa and let's solve more than 1 problem!
     
  4. Beerdog

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    Obviously, it's not a issue of exhausting the sun's energy, but of harvesting and concentrating its energy into a energy dense material suitable for use in our economy and transportation sector. Hydrogen is not suitable as a transportation fuel because it lacks the energy density to be practical to move airplanes and trucks. As a gas it requires heavy, thick walled containment to handle safely.

    The last statistic I saw... now about 9 years old, reported the United States (alone) uses about 20 MILLION barrels of oil per day with about 65% of that going into the transportation sector. Using your number equivalent barrel per square meter per year figure, we'd need to cover 7.3 Billion square meters (20 million x 365 days and assuming 100% conversion efficiency to useable energy). My questions to challenge your concept are:

    Is your vision feasible?
    Are there globally enough rare earth materials, copper or other necessary raw materials?
    Assuming the raw materials were available, how the infrastructure be built? Who would pay for it? Who's land would be taken? How would the costs (economic, social and environmental) be borne?

    I ask these questions not because I am against your concept, but because I am a doubting Thomas. Although my glass is usually half full, I'm not blinded to the concept that it's also half empty.

    John
     
  5. btuser

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    I don't care if there is enough as long as there is enough for me.
     
  6. woodgeek

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    This is a common concern, but not a major problem. We can 'make' oil-like molecules from biomass by cooking it (pyrolysis). Think of it like this...

    Mass(Oil for energy) > > Mass(Bio) > > Mass(Oil for materials)

    We could switch all our plastics production to run off woody biomass and agricultural waste whenever we need to. As oil settles into a $100 average price, several of these processes are starting to get rolled out.

    If there are still trees in the future, our children will have as much plastic as they need.
     
  7. peakbagger

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    We are switching to a hydrogen economy and a lot of folks dont realize it. The chemical formula for methane (the major ingredient of natural gas) is CH4, the formula for oil varies but let use is approximately C8H18. There is no CO2 produced when hydrogen is burnt so the switch to methane in place of oil is major move to hydrogen combustion.

    The downside to methane is that the density of the methane is far lower than oil and hydrogen is even less dense. For a fixed power plant its not a major issue but for transportation, folks want dense fuel so they can drive long distances and thats where oil excels.
     
  8. Seasoned Oak

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    The price of gas needs to go UP for a variety of reasons least of which is to preserve future availability.
     
  9. Beerdog

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    Petebagger...

    The hydrogen economy you reference is nothing more our society making ever greater use of fossil fuel methane (natural gas) over oil or coal. The main reasons more natural gas is being used now for electricity production, at least in the north east, are because it is much less expensive then fuel oil on a cost/Btu basis, there is a glut of natural gas in the market place, and much of the marginal load shaving is done by natural gas fueled engines/turbines. Coal, a low cost competitor, is considered environmentally dirty and it requires expensive emissions controls to minimize particulate, sulfur dioxide and nitrogen oxide emissions. Coal burning produces more carbon dioxide per Btu than natural gas and is not well suited for intermittent use where a power plant starts up and shuts down on a frequent basis. Coal is suited for base load electrical production because it's boilers can not be cycled on and off as peak load shaving of electrical demand requires.

    For further reading, a very good and thorough article was written by Dr. Robert Uhrig: "Engineering Challenges of the Hydrogen Economy" ... link at www.tbp.org/pubs/Features/Sp04Uhrig.pdf

    John
     
  10. Dune

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    This is a common misconception. As the world population increases, biomass is needed for food stock, not fuel stock. Whereas oil is entirely recycleable (minus vapor loss) the less we burn now, the better the future.

    I can't even imagine what your point is in making this argument. ( actually I can but don't want to go there).
     
  11. woodgeek

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    I think we agree that biomass, food or otherwise, is not going to replace FF to a significant measure. I guess we disagree on the much smaller problem of using woody material to make plastic feedstocks....

    Problems:
    --Climate Change
    --Energy
    --Food/Water
    --loss of biodiversity

    Not a problem: (IMO)
    --Earth abundant elements (Al, Fe, Si)
    --Plastics
    --Landfill Space

    The challenges before us need to be prioritized, lest we indulge in 'feel good' solutions to minor problems (recycling??), or add a litany of problems for dramatic effect (no plastics in the future).
     
  12. Dune

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    If you think replacing ten percent of the nations gasoline with corn ethanol is insignificant, then yes.
    Since 20% ethanol could be mandated tomorrow, using food stock for fuel is a serious and genuine concern.

    Consider that food as a cost of an average person's wages increased from 10% of salary (for the entire previous century) to 33% from the implementation of 10% ethanol alone. Starvation rates around the world leapt as a result. The corresponding loss of disposable income has caused an enduring anemic economy.
    How much further down this trail do you think we can go?


    You can make all the bakelite you want from wood, but someday, the tree farms will be needed for food farms.
    It's not a problem at all until the population is that large.
    I advocate the use of woody material to make liguid fuel NOW, and save the oil and coal stock for their vast advantages in manufacturing (especialy oil) Burning oil should be criminal. One oil is made into a plastic good, the mass of it can be re-used almost indefinitely. This is NOT about re-cycling, it is about preserving mass. Once the oil is used as energy, it will never be mass again. We can get all the energy we need without burning oil. We have just been incredibly lazy and greedy until now.
    Burning oil and coal are major contributors to climate change.
    We have an over-abundance of energy available to use. We do not yet have the political will to use it.
    Our true problems, which trump all others. The reason using food stock for fuel is so very wrong.
    Don't forget lithium. We have all the lithium we will ever need.
    The uses for plastics are manifold and increase exponentially. As we speak, the Chinese are manufacturing housing units from recycled plastic.

    Food, then fuel. We would not have significant resources of anything for long without recycling, and ease of manufacturing (cost) is certainly a dramatic effect of any future human venture.

    Iron is the most recycled commodity on earth, followed closely by Al, then Si, to be perfectly clear.
     
  13. woodgeek

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    Dune, I would be happy to wind down the corn ethanol project tomorrow (but might feel differently if I were a farmer). Studies have shown that if we had mandated just a 1-2 point higher mpg in 2002, we would saved more gasoline than ethanol has displaced since then without the food price shocks or the environmental impacts of corn growing. 1 or 2 mpg. Coulda shoulda woulda.

    As for cellulose to oil. Cellulose pyrolysis to gas/oil is easy, and the resulting stuff can be readily converted to feedstocks for plastics and other fine chemicals. Shell has been making biomass pyrolysis oils at some of their petroleum refineries, as it often has a higher H content than heavy FF, and allows them to make lighter products out of heavy oil. (This is as opposed to using NG derived H for this purpose)

    Personally, I am not too worried about running out of cellulose. The terrestrial biosphere pretty much just makes cellulose, and us habitual seed eating primates can't digest the stuff. Might as well use it to build houses, produce plastics and maybe heat some nice passive houses.

    And while we're at it....can we stop labeling socks made from rayon as 'bamboo socks'?
     
  14. begreen

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    I'm not in favor of using corn for ethanol for a lot of reasons. Using switchgrass and landfill waste to create fuel is fine with me. The sooner the better.
     
  15. Seasoned Oak

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    Indeed BG Corn is a High impact crop.Needing a lot of everything to grow,space, water, fertilizer,pesticides. If not done correctly it can also contribute to land erosion. NO way should we be using it for a fuel feedstock.
    Only enough ethanol to offset the lead for octane purposes should be allowed.
     
  16. Dune

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    Why not methanol Randy? Why use any ethanol at all?
     
  17. Beerdog

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    Whether or not corn derived ethanol results in a net systematic Btu gain or loss is highly dependent on where boundaries are drawn around the process. Some economists say the process has a net gain in Btu and some say not. Whatever the analysis, creating ethanol from corn is socially irresponsible in that it decreases food production resulting in higher costs for corn, other grains and animal feed. Grain formerly shipped off to feed the starving peoples of the world was instead diverted for use as a chemical feed stock. Further compounding the immorality, the ethanol economy subsidized by tax dollars.

    The main reason ethanol is used is because of political pressure by a green lobby that retains gasoline oxygenate mandates and minimum amounts of bio-derived fuels in gasoline. Oxygenates are unnecessary due to vehicle's computer control over the fuel/oxygen mixture, but the ban of inexpensive MTBE (methyl-t-butyl ether) opened the door for an ethanol industry sucking the lifeblood out of us due to subsidies and mandates. A lot of new tractors sales were made the switchover took place and John Deere stock was a high flyer.

    I worked doing emissions research and our data was used to petition EPA to eliminate the oxygenate mandate but too many vested interests prevailed, and we're still paying for the outdated oxygenate mandate and subsidized ethanol.
     
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  18. Bret Chase

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    Methanol is a difficult animal.... it requires a stainless tank because it is much more corrosive than ethanol... and methanol can burn in a confined space (i.e. a gas tank)... and burns with a colorless flame....
     

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