Good read: How Hydrogen Can Save America

[silverpig]

Originally posted by: Howard
One acre of sugarcane can yield up to 2200 gallons of ethanol per year

GM crops that make their own nitrogen fertilizer like legumes can make the process considerably cheaper.

How much energy could a 1 acre solar array generate in one year? I imagine it would be able to electrolyse more than the equivalent in hydrogen fuel, and you get a better product.

 

[sandorski]

Originally posted by: etech

Originally posted by: Phuz

Originally posted by: etech

Originally posted by: HeroOfPellinor

Originally posted by: Phuz
Technologies aside, the article points out the factors restricting this type of progress from happening. Of course the technology is possible..

The article offers no insight whatsoever on the issue other than to say we need to dump more money into it.

I have to agree with that. It says that all of the possible problems and there are many can be solved simply by more funding.Sometimes that works and sometimes it doesn't.

The main hurdle is where to get the energy to produce the hydrogen. Windmills and solar just won't do it.

No. The main hurdle is gaining the necessary attention to the fact that we're just going to keep using oil until its gone. Also, being able to actually say your countries source of power is purely domestic would be nice, wouldn't it? I don't see how it can be more beneficial to be dependent on foreign resources.
Hence the analogy of putting the man on the moon. When it was decided that it was a serious priority to (beat the competition) put a man on the moon, America made it happen. The funding was there. It helped that most everyone was for putting a man on the moon, however, most everyone isn't for converting to another source of energy. Oil companies are fairly influential.

How much money? How about the amount spent to put a man on the moon: $100 billion in today's dollars. With that investment, the nation could shift the balance of power from foreign oil producers to US energy consumers within a decade. By 2013, a third of all new cars sold could be hydrogen-powered, 15 percent of the nation's gas stations could pump hydrogen, and the US could get more than half its energy from domestic sources, putting independence within reach. All that's missing is a national commitment to make it happen.

That's nice and all but where will the energy come from to produce the hydrogen?

This is a different situation then putting a man on the moon. That was simply a engineering exercise, an awesome one to be sure but still just engineering. The question of where the energy to proude the hydrogen is coming from is a fundenmtal question that cannot be solved simply by engineering.

Iceland will be using GeoThermal produced electricity to generate the necessary power. The same technology could be employed in Hawaii and at a number of active volcanic sites. Even some inactive volcanic sites, I'm guessing, would be likely sources of GeoThermal power such as Mt St Helens and Mt Ranier. There are also a number of areas where natural Hot Springs occur that would make good GeoThermal sources.

 

[spyordie007]

Originally posted by: silverpig

Originally posted by: Howard
One acre of sugarcane can yield up to 2200 gallons of ethanol per year

GM crops that make their own nitrogen fertilizer like legumes can make the process considerably cheaper.

How much energy could a 1 acre solar array generate in one year? I imagine it would be able to electrolyse more than the equivalent in hydrogen fuel, and you get a better product.

according to this website when the sun is overhead a single acre of land is bathed in about 4,000 HP of energy, it may indeed prove more efficient to go from electricity to the grid and take what is left over into hydrogen with a system such as this.

-Spy

 

[spyordie007]

assuming 25% efficient photovoltaic cells (again like I said you can be even more efficient with Gensets) that is about 745Kw output from a single acre of land. Increase the efficiency of your solar collectors and you could easily get a higher output (you do the math).

-Spy

 

[Howard]

Originally posted by: spyordie007
assuming 25% efficient photovoltaic cells (again like I said you can be even more efficient with Gensets) that is about 745Kw output from a single acre of land. Increase the efficiency of your solar collectors and you could easily get a higher output (you do the math).

-Spy

PV cells can reach roughly 50% efficiency now...

 

[spyordie007]

Originally posted by: Howard

Originally posted by: spyordie007
assuming 25% efficient photovoltaic cells (again like I said you can be even more efficient with Gensets) that is about 745Kw output from a single acre of land. Increase the efficiency of your solar collectors and you could easily get a higher output (you do the math).

-Spy

PV cells can reach roughly 50% efficiency now...

awesome, I had no idea that they had been able to increase efficiency that much over the past few years. Make that 11450Kw+ output from that same acre of land.

-Spy

 

[silverpig]

11450 KW of power = 11450 KJ/s

Let's assume that this particulary area is pretty sunny, so it gets direct sunlight 65% of it's days and 12 hrs a day.

365 x .65 = 237.25 days/yr of direct sunlight

327.25 days/yr x 12 sunlit hours/day = 2847 hr/yr of good sunlight

2847 hr/yr x 3600 sec/hr = 10 249 200 sec/yr of good sunlight

10 249 000 sec/yr x 11450 KJ/s = 117 353 340 000 KJ/year from one acre of sunlit land



This site says that ethanol has about 77000 BTU of energy per gallon.

2200 gal x 77000 BTU/gal = 169 400 000 BTU

1 BTU = 1054.8 J

169 400 000 BTU = 178 683 120 000 J per year.

1 KJ = 1000 J

So you get 178 683 120 KJ per year in ethanol per acre of land compared to the 117 353 340 000 KJ per year per acre of land of solar panels.



Doing the division shows that you get ~656x the amount of energy out of 1 acre of land if you cover it with solar panels as opposed to sugar cane.




edit: did the 50% efficience thing twice. fixed now

 

[silverpig]

All that math for nothin'

 

[spyordie007]

Originally posted by: silverpig
All that math for nothin'

I saw it, you rock!

plug
Come join my forums (link below)
/plug

-Spy

 

[Lithium381]

wow that's actually an interesting read! though kinda out there, it IS possible...

 

[ReiAyanami]

oh man, then why does electricity cost so much in cali. they should just build us some sugary solar panels cuz out here is desertz

 

[zephyrprime]

PV cells can reach roughly 50% efficiency now...

I'd like to see proof of that. I searched the web and found no information confirming such a high efficiency cell.

common efficiencies
record holders

I read some talk of multijunction cells that could attain 50%+ but that's all just talk. talk

Common solar cells have about ~10-15% efficiencies. The most cost effective cells are also the least efficient type (no surprise).

I've also read some stuff about a radically different sort of cell that's not a semiconducting device at all but rather a nanoscale array of antennas. That idea is interesting but I've not heard of it successfully being built yet.

 

[Howard]

Bah! I was wrong again!

Research cells using single-crystal Si have reached about 24% instead...

http://www.voltaicpower.com/Solar/photo-thick.htm

 

[BaliBabyDoc]

Your link is not a good read. If America had the semblance of intestinal fortitude when it comes to energy independence there would be fleets of hybrid cars on the road getting 30 - 50 mpg (SUV to compact). Our government (and domestic automakers) spent billions to NOT produce a viable hybrid while Honda/Toyota field multiple vehicles and the Germans aren't far behind.

The most dominant trend in autos over the past 5 years has been MORE horsepower and MORE SUVs . . . Hydrogen won't save America b/c our ethos is NO compromises. We want more for less . . . unless of course you're talking about gas mileage.

 

[spyordie007]

Originally posted by: BaliBabyDoc
Your link is not a good read. If America had the semblance of intestinal fortitude when it comes to energy independence there would be fleets of hybrid cars on the road getting 30 - 50 mpg (SUV to compact). Our government (and domestic automakers) spent billions to NOT produce a viable hybrid while Honda/Toyota field multiple vehicles and the Germans aren't far behind.

The most dominant trend in autos over the past 5 years has been MORE horsepower and MORE SUVs . . . Hydrogen won't save America b/c our ethos is NO compromises. We want more for less . . . unless of course you're talking about gas mileage.

Hydrogen offers just this, a standard gasoline (ICE) engine converted to run on Hydrogen will yield a 10-15% HP gain because Hydrogen burns quicker. Not only that but your engine will last signifigantly longer.

Besides you know how much all those morons driving around in their SUVs with the "God bless America" stickers would love to think that they are fighting terrorism and buying American...

(sarcasm intended if you didnt catch it)

-Spy

 

[KenGr]

All the discussion on PV efficiency and potential yeilds seems not to have mentioned the other critical portion of the equation - intensity of sunlight. Even with the expense of tracking systems, intensity peaks for only a couple of hours a day and, on the average of over half the day, is essentially unavailable. Winter performance, even in the southern US is limited. Right now this remains the stumbling block.

In the US, no one has been able to justify a large PV installation, even with significant subsidies and tax incentives. There have been some steam cycle (reflector/collector) systems that, with tax breaks, have been almost breakeven. However, the largest (SEGS in Southern California) qualified for tax breaks but generates almost half of it's power with oil or gas to offset the excessive capital costs. (It also created an environmental disaster when it caught on fire and dumped large amounts of heat transfer oil in the desert.)

We all wish it was the answer but solar, in any form, isn't ready for prime time. (I know someone is going to say we just need more research but I've been following solar power since I was an undergraduate in Engineering school. There's been plenty of money for all promising technologies and today, as I near retirement, it hasn't made enough progress.) Solar will not become the choice technology because of lower solar costs but only because of major increases in cost of other technologies.

 

[spyordie007]

Originally posted by: KenGr
All the discussion on PV efficiency and potential yeilds seems not to have mentioned the other critical portion of the equation - intensity of sunlight. Even with the expense of tracking systems, intensity peaks for only a couple of hours a day and, on the average of over half the day, is essentially unavailable. Winter performance, even in the southern US is limited. Right now this remains the stumbling block.

In the US, no one has been able to justify a large PV installation, even with significant subsidies and tax incentives. There have been some steam cycle (reflector/collector) systems that, with tax breaks, have been almost breakeven. However, the largest (SEGS in Southern California) qualified for tax breaks but generates almost half of it's power with oil or gas to offset the excessive capital costs. (It also created an environmental disaster when it caught on fire and dumped large amounts of heat transfer oil in the desert.)

We all wish it was the answer but solar, in any form, isn't ready for prime time. (I know someone is going to say we just need more research but I've been following solar power since I was an undergraduate in Engineering school. There's been plenty of money for all promising technologies and today, as I near retirement, it hasn't made enough progress.) Solar will not become the choice technology because of lower solar costs but only because of major increases in cost of other technologies.

You are absolutly right in that many places on the earth just dont get enough light to make it worth the investment, however as the technology of "solar energy harvesting" increases and the cost decreases it will become more practical. Another important thing to note is that there are plenty of places on earth that get enough light to make it worth their while now, think about all the costal regions of Africa and Mexico that get plenty of sunlight and have easy access to plenty of water. A company could easily setup a system down there to run off of solar power (think gensets and not PV since gensets are currently the most efficient and cost far less than PV), they could than sell the pure Hydrogen for immediate energy usage and the pure oxygen for a number of commercial applications (right now oxygen gas sells for considerably higher prices than hydrogen). Those regions could become the next middle east!

-Spy

 

[Mallow]

thx

 

[Mani]

Interesting thread. I am very confident that there are perfectly viable alternative energy sources but they just require a large investment of time and money, and the only entity capable of driving to a new energy standard (our government) is not interested in doing so for a number of reasons.

 

[MercenaryForHire]

Hydrogen can save America by being packed into bombs and sent Express Courier Via B-2 to Iraq.



- M4H

 

[Armitage]

Originally posted by: silverpig
11450 KW of power = 11450 KJ/s

Let's assume that this particulary area is pretty sunny, so it gets direct sunlight 65% of it's days and 12 hrs a day.

Even if you have your arrays tracking the sun, you won't get anywhere near 100% for 12 hours a day, even at the equator. At mid latitudes, even less, especially in the winter. And mechanical trackers will add considerably to your up front & recurring costs.

365 x .65 = 237.25 days/yr of direct sunlight

327.25 days/yr x 12 sunlit hours/day = 2847 hr/yr of good sunlight

2847 hr/yr x 3600 sec/hr = 10 249 200 sec/yr of good sunlight

10 249 000 sec/yr x 11450 KJ/s = 117 353 340 000 KJ/year from one acre of sunlit land

Ok, I must be missing something here. what is you conversion factor between "seconds of good sunlight/acre" and Kilojoules/year???

A decent estimate of solar irradiance on orbit is about 1358 W/m^2 (Space Mission Analysis & Design, 2nd Ed.). Of this, IIRC, roughly 50% is available @ sea level at noon (need to confirm this). So, a plate perpendicular to the sun at noon at sea level would bring in about 679 W/m^2 or 679 J/m^2/s If you don't track the sun, this number is proportional to the cosine of the angle between teh collector normal on the sun.

1 acre = 4046.8726 m^2

So, 1 acre receives roughly 2748 KJ/s

Now, apply a reasonable figure for PV efficiency, say 24%

2748 KJ/acre/s * 0.24 = 660 KJ/acre/s

Efficiency of electrolysis of water is roughly 60% IIRC from previous ATOT debates on this subject. So the energy content of the hydrogen that this acre could produce is roughly:

660 KJ/acre/s * 0.6 = 396 KJ/acre/s

Let's use you highly optomistic time numbers above:

396 KJ/acre/s*10249000s = 4,100,000,000 KJ/acre/yr Still considerably better better then the ethanol numbers, but not nearly what you had come up with.

Now, 1 gallon of gas has an energy content of 115,000 btu/hr

1 btu = 1.0551 KJ

1 gallon gas = 121,331 KJ

So, 1 acre could potentially produce the energy equivalent of 33450 gallons of gas per year.

I found a consumer price for PV arrays of roughly $500/m^2, so 1 acre of PV arrays would be about $2.1 million + cost for tracking mounts, electrolysis system, & all the other infrastructure. Economies of scale will bring the PV cost down, so lets be optomistic and call it $2.1 million total capital investment/acre + some ongoing operating & maintenance cost.

So, not counting the ongoing cost, it would have to produce the equivalent of 1.25 million gallons of gas @ $2/gallon to recoup the capital costs. At 33450 gallons/year that would take roughly 31 years to recoup the capital investment, if you could turn it on and walk away ... ie. no operating costs at all. Of course this is a complete WAG, but it's probably in the ballpark.

Good luck finding investors.

By contrast, the infrastructure cost for ethanol is likely to be quite a bit lower, particularly because you don't need to replace all the infrastructure we didn't even consider here ... vehicles, distribution system, etc.

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