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This is one of those grand myths that the public just can't shake. Photovoltaic's have a very good energy return on investment (EROI).

The energy payback peroid for various PV cell types are:
Crystal Silicon: 3.3 years
Multicrystal Si: 0.8 years
CIS: 0.4 years

To put that is perspective of EROI:
Photovoltaics (Si): 60:1 - 10:1 (based on above)
Wind: 60:1
Coal(US average): 9:1
Nuclear (light water): 4:1
Oil (mid-east): 10:1 - 30:1
Oil (US): 3:1 or less

And that is keeping in mind that the lifespan of PV is calculated at 30 years, an arbitrary number picked to equalize it with the life of a coal or nuclear power plant, however are panel warranties are 20-30 years alone. There is no reason to believe that the average lifespan of a PV panel won't be 40-60 years or more.

This is one of those grand myths that the public just can't shake. Photovoltaic's have a very good energy return on investment (EROI).

The energy payback peroid for various PV cell types are:
Crystal Silicon: 3.3 years
Multicrystal Si: 0.8 years
CIS: 0.4 years

To put that is perspective of EROI:
Photovoltaics (Si): 60:1 - 10:1 (based on above)
Wind: 60:1
Coal(US average): 9:1
Nuclear (light water): 4:1
Oil (mid-east): 10:1 - 30:1
Oil (US): 3:1 or less

And that is keeping in mind that the lifespan of PV is calculated at 30 years, an arbitrary number picked to equalize it with the life of a coal or nuclear power plant, however are panel warranties are 20-30 years alone. There is no reason to believe that the average lifespan of a PV panel won't be 40-60 years or more.

This is one of those grand myths that the public just can't shake. Photovoltaic's have a very good energy return on investment (EROI).

The energy payback peroid for various PV cell types are:
Crystal Silicon: 3.3 years
Multicrystal Si: 0.8 years
CIS: 0.4 years

To put that is perspective of EROI:
Photovoltaics (Si): 60:1 - 10:1 (based on above)
Wind: 60:1
Coal(US average): 9:1
Nuclear (light water): 4:1
Oil (mid-east): 10:1 - 30:1
Oil (US): 3:1 or less

And that is keeping in mind that the lifespan of PV is calculated at 30 years, an arbitrary number picked to equalize it with the life of a coal or nuclear power plant, however are panel warranties are 20-30 years alone. There is no reason to believe that the average lifespan of a PV panel won't be 40-60 years or more.

I recommend Seed as well.

A few more are World Science and EROEI.com and Physorg.

Cells will fail and will need replacing from time to time, and will be expensive to do.

Most manufacturers Guarantee their panels for 20-30 years, so that is minimum life. Of course on average they will last longer. Longer than most power plants, and yes, virtually maintenance free.

home energy usage is pretty much the exact inverse of when the most solar radiation is available

In fact, the average electricity demand on the grid typically follows the sun cycles, especially in summer when electricity use peaks. The peak grid loads are typically ~40% higher at midday than the nighttime minimum. Even in the winter, when the day peaking is less pronounced (and shifted towards morning/evening), solar could address as much as 35-40% the national electricity demand even without storage. See http://currentenergy.lbl.gov/pjm/index.php for an example of demand curves.

Of course storage on the grid is important, and needs work, but we could address a HUGE amount of US electrical need without it.

However, for serious microgeneration, at the current time the only halfway practical and affordable renewable energy source is wind, which is vastly cheaper

Wind is very cheap, not halfway practical cheap, but cheap as coal cheap. Hydro is very cheap as in cheaper than coal cheap, and photovoltaics are the cheapest thing going when you don't have a 100 year old subsidized grid infrastructure. Because of that, photovoltaics is the only option in many places in the developing world, because the cost of the lines is 10 times more expensive than the coal plant that make the power. But more importantly, PV is getting exponentially cheaper to manufacture by the decade, and new low cost technologies are just starting to leak out of the lab into a marketplace near you. (However, note that demand has outstripped supply by 30% with 40%/year growth in the market for several years, even if the manufacturing is getting cheaper, it is not currently seen in the market because of high demand).

Bottom line, renewables are the cheapest things going, even without addressing the huge subsidy imbalance going to traditional fuel sources (oil, coal, nuclear, etc)

The energy to make a typical wind turbine is generated by the turbine over a period of six months - it's more like 6 years for solar.

Photovoltaics cells have an energy pay-back period ranging from 3 months for newer technologies (e.g. CIS, CdTe) to 3 years for traditional crystalline silicon. Even mainstream multi-crystal silicon has a payback period of 0.8 years. And these numbers don't even address the newer, and lower embodied energy low cost multi-junction concentrators or low temp printable cells.

So when you look at a 30 year life span, that gives PV an Energy return on investment of 10:1 for Crystal Si, 37:1 for multi-Crystal Si, and 100:1 with CIS. Compare that to typical fuels: Coal (9:1), nuclear (4:1), US oil (3:1), Mid-east oil (10:1-30:1).

Unless photo voltaic solar becomes vastly cheaper, it's simply a non-contender except for novelty value, even if you live in the desert.

A desert is not needed as solar insolation is relatively uniform throughout the US (and world). The best location in Arizona is only twice as good as the worst place in the Washington rainforest, with the majority of the US within 80% insolation of the best location in Arizona!

Even with today's "high" PV prices, PV is unique in that it is deployable on any rooftop, parking lot, or yard at the point of use. With net-metering or battery storage that means PV competes with retail energy not w

A look at a small table of energy return on energy invested figures gives ethanol from corn a 1.3, ethanol from sugarcane something like 0.8 to 1.7 (meaning it could possibly be a net energy loser!), and ethanol from corn residues 0.7 to 1.8. Compare that with petroleum's EROEI, which is today something of the order of 23, and had once been higher than 100. Even at the maximum efficiency level, it would probably take dedicating all of the arable land in the United States to grow corn for conversion to ethanol to allow business as usual. Also, mechanized farming techniques are so heavily dependent on petroleum-based (and natural gas based) fertilizers and pesticides. Here's a good article on how to properly evaluate these schemes for alternative energy, and ethanol doesn't fare very well.

No, the only real solution to the energy crisis is to abandon the grossly wasteful American way of life, and take steps towards serious conservation efforts.

It depends how and from what you make your ethanol. And how you farm your feedstock of course...

Brazil does just fine with it's sugarcane:

http://www.eroei.com/articles/16_jun_05_brazil_fue l_p.html

Lithium requires a lot of energy and sophisticated and highly energetic processes:

http://www.nccp.ru/EN/Li/

and tantalum requires enormous energy to dig up, melt the rock and process it to get the tantalum.

I realise that the experiment was more a "proof of concept" and not an energy producing victory, BUT:

Any cold fusion process is going to have to kick out a FUCKLOAD of energy to merit attention, given the energy intensiveness of the process of just assembling the parts. Otherwise, it fails the EROEI test.

http://www.eroei.com/

RS

The EROEI is largely irrelevant. It is (very) difficult to quantify and the EROEI comparisons do not give us much meaningful information. Some forms of energy are more useful than others.

Even if the EROEI ratio on using sunlight to make hydrogen is very low (compared to for instance pumping oil), the process is still useful, since no car runs on sunlight. It matters more if the result is useful and if the process is profitable. Oil companies don't care about EROEI and never will.

First, of course it matters whether or not the 'overall (land) efficiency' is 10-40%. It matters by a factor of four. It turns your estimate of 7% of texas (which is IMO too low) to about 28% of texas, just for collection.

Your whole argument is based on the fact that 'we can use solar without the further use of land' - if we need to cover the equivalent of texas/alaska with solar cells, of course this simply isn't true.

Second, look at the entech doc that you gave me, specifically figure 4:

PVUSA long term performance data:

Array DC efficiency (ranges from 2% to 14%)

So, the '30% efficient cell' becomes 14% DC efficiency, before any storage costs are considered, and before DC => AC costs are considered, and hence you need to at least double your land estimates.

Third, look at the EROEI document that you gave me, and look under 'solar':

eroei

Note that Odum has given a value of .41 (as in less than one) to solar voltaics. Cleveland gives 1.7 (improvable to 5.1) to 10.1 (improvable to 30.1).

Now, why are the numbers different? It depends on *methodology*. Your paper - the one that cites the EROEIs of 30-75 - is fairly limited in scope when it comes to energy and environmental impact. It even says so in the LCA scope: that they are only going to be dealing with *production* energy costs (its not clear about whether mining costs are included).

Hence, the EROEIs that you give are tailor made to be more rosy than the overall numbers. Cleveland tends to be out in lala land, because he doesn't base his analysis on economic study rather than scientific study(?) which inherently makes upcoming new technologies more rosy than they actually are (ie: all that hype surrounding them). It also didn't help that the study you cited was done right in the middle of a economic bubble, further distorting it.

Which is why I favor Odum's numbers (from 'Environmental Accounting'), which include:

1) design installation
2) collector materials cost
3) collector cost
4) administrative cost
5) operation and maintenance
6) concrete and other building materials
7) structural aluminum and other supporting
materials
8) rebar costs
9) wiring costs
10) operational facilities

And is where he gets the overall EROEI of .41.

Furthermore, they are based on a real, voltaic power installation in Texas, which operated throughout the 1990s, and are based on an audit performed by the operational manager. (he's done a couple more audits like these, and they've all come out about the same - things are slowly improving, but institutional efficiency always lags)

*Thats* where the EROEI comes down - when you take in account all the supporting infrastructure that surrounds the collection source. After all, if you only look at the EROEI of the wellheads, whilst forgetting the refineries, pipelines, and so forth, oil's 'EROEI' comes out to over 200, too.

So when you say that the EROEI of Solar is 75 versus the EROEI of oil being 10-30 and light-water nuclear being 4, that's exceedingly misleading. You really are comparing apples to pears here.

What is more fair is if you do the same analysis for each source of power in the same way, like Odum has done. And in this case, solar comes out fairly poorly (which of course is *why* its .1% of our energy source, even after 130 years of research).

Now - that's not to say I completely agree with Odum. The EROEI he gives - .41 - was on an installation that was intent on providing baseline power (which solar does horribly unwell), and installations that are directly on top of houses for local power supply will probably perform much better (even if there is still the question of storage penalty).

But all this really points to is that solar has its nic

Alsema is a leading expert on this field on study (you'll see his name on many in-depth studies) and shows the energy pay back period to be:
Multicrystal Si: 0.8 years (EROEI 37.5 @30y, 62.5 @yr)
CIS: 0.4 years (EROEI 75 @30y, 125 @50y)
CdTe: 0.6 years (EROEI 50 @ 30y, 83 @ 50y)
Crystal Si: 3.3 years (EROEI 9 @30y, 15 @50y)

I should note that these studies are again becoming 5-10 years old again and don't reflect the improvements in efficiency. CIS for example in this study was modeled at 12% efficiency, but the best efficiency (2003) is now 19.2%. Same with crystal Si, efficiency have edged up about 3-4%. I wasn't able to find info on concentrators, but because of low materials-to-power ratio I expect they will be at least as good.

I calculated the numbers for both 30 years and 50 years. Comparisons are usually done on a 30 year basis since this is the build life of other power plants and is a typical load period. However it is a bogus, made up number for easy comparison. Many PV manufacturers are guarantying their panels for 25 years, with no or little power degradation from the specs. No reason to artificially cut their life short.

The numbers I used were the base case, not best. Of course its possible to package them with material having more embodied energy (as in the case of the silicon numbers which has a significant amount of aluminum in the frame). Now these don't include infrastructural embodied energy such as inverters, mounting systems etc, which would decrease the EROEI to about 30 @ 30 years with current techniques. But neither do the EROEIs for traditional fuels contain the externalities of generation plant embodied energy. Other energy sources are:
Coal: 9 EROEI
Oil (middle east): 10-30 EROEI
Oil (US): 3 EROEI
Light water Nuclear: 4 EROEI current (12 with improvements)
Ethanol: Likely zero EROEI, maybe negative

Now you might quibble with some of the numbers, however I think it shows that PV is at worst good, and at best really good.

Alsema is a leading expert on this field on study (you'll see his name on many in-depth studies) and shows the energy pay back period to be:
Multicrystal Si: 0.8 years (EROEI 37.5 @30y, 62.5 @yr)
CIS: 0.4 years (EROEI 75 @30y, 125 @50y)
CdTe: 0.6 years (EROEI 50 @ 30y, 83 @ 50y)
Crystal Si: 3.3 years (EROEI 9 @30y, 15 @50y)

I should note that these studies are again becoming 5-10 years old again and don't reflect the improvements in efficiency. CIS for example in this study was modeled at 12% efficiency, but the best efficiency (2003) is now 19.2%. Same with crystal Si, efficiency have edged up about 3-4%. I wasn't able to find info on concentrators, but because of low materials-to-power ratio I expect they will be at least as good.

I calculated the numbers for both 30 years and 50 years. Comparisons are usually done on a 30 year basis since this is the build life of other power plants and is a typical load period. However it is a bogus, made up number for easy comparison. Many PV manufacturers are guarantying their panels for 25 years, with no or little power degradation from the specs. No reason to artificially cut their life short.

The numbers I used were the base case, not best. Of course its possible to package them with material having more embodied energy (as in the case of the silicon numbers which has a significant amount of aluminum in the frame). Now these don't include infrastructural embodied energy such as inverters, mounting systems etc, which would decrease the EROEI to about 30 @ 30 years with current techniques. But neither do the EROEIs for traditional fuels contain the externalities of generation plant embodied energy. Other energy sources are:
Coal: 9 EROEI
Oil (middle east): 10-30 EROEI
Oil (US): 3 EROEI
Light water Nuclear: 4 EROEI current (12 with improvements)
Ethanol: Likely zero EROEI, maybe negative

Now you might quibble with some of the numbers, however I think it shows that PV is at worst good, and at best really good.