Energy Returned on Energy Invested Thread pt 2 (EROEI) (merg

[jbeckton]

So we start with a significant(?) investment of energy to get the process started. Once we've reached production/installation stage the EROEI starts to rise and continues to rise to infinity.

Unlike oil or coal, where the EROEI is descending towards zero.

This statements tells me you do not know what energy return is about. Eroei is a constant measure minimally affected by increases in process efficiency and decreases in energy availability.

Your statement shows that you don't know what energy return is about.

If efficiency doubles, what happens to energy return?

minimally affected by increases in process efficiency

Give me a break.

If it is mass produced (increase in process efficiency) its EI goes way down.

Where do you get off trying to tell people that they don't know what they are talking about when you clearly don't know yourself?

Doomer yourself away its ok with me, just don't start making things up.

[jbeckton]

The cost of collecting solar thermal energy equivalent to one barrel of oil is about US$50 right now (already less than the current world price of oil) and is likely to come down to around US$20 in the future.

Solar thermal and wind are ready ringt now, thin film will be next.
http://europe.theoildrum.com/node/2583

[pstarr]

Your statement shows that you don't know what energy return is about. If efficiency doubles, what happens to energy return?

I said 'minimally' affected not 'not' affected. I question the notion that eroei can 'rise to infinity.' It alway takes energy to harness and direct a primary energy source (whether it be coal, wind, or nuclear) to our industrial infrastructure and there will be a difference between the net energy available to society for productive work and the original gross embodied energy.

Yes, of course efficiency changes the equation but it is also quite apparent that efficiency improvements have run their course and thus entropy in the form of CO2 and global warming have become the pertinent issue of the day.

Where do you get off trying to tell people that they don't know what they are talking about when you clearly don't know yourself?

Doomer yourself away its ok with me, just don't start making things up.

I am only a doomer because I have to deal with self-justified denialists like yourself.

[jbeckton]

I said 'minimally' affected not 'not' affected. I question the notion that eroei can 'rise to infinity.

Rise to infinity? No, rise towards infinity, yes.

Consider it an exponential function when ERoEI is plotted against time.

Explain how a product that goes from small scale testing, to mass production while its efficiency goes from 4%-20% has a "minimally affected ERoEI"

It alway takes energy to harness and direct a primary energy source (whether it be coal, wind, or nuclear) to our industrial infrastructure and there will be a difference between the net energy available to society for productive work and the original gross embodied energy.

Yes, but that energy is invested up front, and being a source that requires virtually no energy investment for fuel delivery, or operation, the return is not hindered by continued energy investment. Which is what he was saying, which you took out of context.

Yes, of course efficiency changes the equation but it is also quite apparent that efficiency improvements have run their course and thus entropy in the form of CO2 and global warming have become the pertinent issue of the day.

Run their course? For the coal power plant rankine cycle, sure. But for a technology in it's infancy, no way!

And don't bring up entropy, I know that you don't understand the concept; you just like to repeat things you have read.

I'm not impressed.

[BobWallace]

Yes, "toward", not "to". Sorry didn't catch that while proofing.

However, anyone with reasonable math skills shouldn't have been bothered by that slip. One should know that the slope would approach, but not reach, infinity.

I suppose this is a case of someone wanting to be right, even when they are wrong, and picking out one small detail to attack.

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There's a problem with folks who use EROEI and Jevons Paradox to predict the end of the world (as we know it).

They aren't looking at the big picture. They take a small concept and try to apply it to the great big world and miss lots of other factors.

They need to get past the idea that energy=oil=energy and on to the appreciation that there is lots and lots of energy available for our use.

Lots more than we can ever use.

And we know how to harness it. We just need to get busy (very busy) making it happen before we deal ourselves too painful a future.

[pstarr]

I said 'minimally' affected not 'not' affected. I question the notion that eroei can 'rise to infinity.

Rise to infinity? No, rise towards infinity, yes.

Consider it an exponential function when ERoEI is plotted against time.

Explain how a product that goes from small scale testing, to mass production while its efficiency goes from 4%-20% has a "minimally affected ERoEI"

Jbecton this is a load of relativistic sooty nonsence and you know it. 20% increase in efficiency from coal or silica-based solar is not going to happen. There will be no more efficiency gains of that level burning fossil fuel, manufacturing solar panels, or utilizing the remaining energy we have.

It alway takes energy to harness and direct a primary energy source (whether it be coal, wind, or nuclear) to our industrial infrastructure and there will be a difference between the net energy available to society for productive work and the original gross embodied energy.

Yes, but that energy is invested up front, and being a source that requires virtually no energy investment for fuel delivery, or operation, the return is not hindered by continued energy investment. Which is what he was saying, which you took out of context.

But solar panels require immense amounts of energy to crystalize silica and the material we are using now is subsidized by the computer industry. And new transmission lines. How do you expect to operate our suburban infrastructure on 8:1 electric eroei?

Yes, of course efficiency changes the equation but it is also quite apparent that efficiency improvements have run their course and thus entropy in the form of CO2 and global warming have become the pertinent issue of the day.

Run their course? For the coal power plant rankine cycle, sure. But for a technology in it's infancy, no way!

And don't bring up entropy, I know that you don't understand the concept; you just like to repeat things you have read.

I'm not impressed.

You sound like the biofuel techtopians around here. Solar is not new. I have solar on my house that is barely more efficient than solar panels made 20 years ago.

Entropy? Def: we have worn out our options. Anyone for clean coal?

[pstarr]

There's a problem with folks who use EROEI and Jevons Paradox to predict the end of the world (as we know it).

They aren't looking at the big picture. They take a small concept and try to apply it to the great big world and miss lots of other factors.

They need to get past the idea that energy=oil=energy and on to the appreciation that there is lots and lots of energy available for our use.

Lots more than we can ever use.

And we know how to harness it. We just need to get busy (very busy) making it happen before we deal ourselves too painful a future.

I am in agreement with you up to a point. We had an opportunity 30 years ago to create a sustainable, renewable electric infrastructure. I wish we had a national network of trolleys, light rail, and trains as existed in Pennsylvania until the 1950's that we could electrify. I read Jeremy Rifkin, dreamed of the 'hydrogen economy.' I 've had solar panels on my roof for years and my new home will be covered with them. However this is as much a defensive as optimistic move, as I have few hopes for the grid.

It would have taken a national commitment and we had an opportunity under with Jimmy Carter. It was damaged by Reagan and ruined by GW. Now peak is upon us and we are truly screwed. Call me doomer.

[Dezakin]

At that point the EROEI number tells us that we should walk away from that well.

It doesn't even tell us that. If we have cheap energy from another source that happens to make bad fuel (say nuclear power or wind), we'll convert the cheap energy into good fuel at a loss and still make a profit. We might conceivably have windpowered stripper wells someday if we dont allready.

Energy return is a useless concept that confuses people without actually shedding any light. Its important when utilizing a new source of primary energy that its positive. Thats it. The rest is better determined by money or labor than energy accounting.

[pstarr]

At that point the EROEI number tells us that we should walk away from that well.

It doesn't even tell us that. If we have cheap energy from another source that happens to make bad fuel (say nuclear power or wind), we'll convert the cheap energy into good fuel at a loss and still make a profit. We might conceivably have windpowered stripper wells someday if we dont allready.

Energy return is a useless concept that confuses people without actually shedding any light. Its important when utilizing a new source of primary energy that its positive. Thats it. The rest is better determined by money or labor than energy accounting.

You have built your argument on a ridiculous hypothetical.You said "if we have a cheap energy from another source . . . " Well we don't. Petroleum was that cheap energy that every other energy is dependent upon. Coal and uranium depends on trucks and railroads for transport. etc. No other fuel will propel this society. Maybe a different one. But not the one built and refined over the last 150 years.

[BobWallace]

A bunch of points. Let's see what I can remember.... ;o)

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Panel efficiency. The panels that you (and I) bought several years ago were about 8% efficient. There are two proven methods of building panels that are ~40% efficient.

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Panels don't need to get more efficient (for normal use). They just need to get less expensive per watt produced. We've got loads of rooftops available to stick panels.

Panels need to get more efficient for specialized use such as satellites where it costs large amounts of money to get the panels into orbit.

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Thin film panels are now shipping at less than $1.50 per watt - wholesale. That bring solar into competition with new nuclear.

Apparently a new company will begin shipping thin film for $1 per watt in the next few months.

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The amount of energy required to produce panels has greatly declined over time. The payback for a new panel placed in a solar-rich environment such as Arizona is measured in weeks.

(Seems like the number is in the 7-8 week range.)

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If one looks at the "OMG We're Running Out of Oil!!!" charts that the doomers put up it shows that we should have about as much oil in 2020 as we had in 2000.

What does that mean? That if we conserve (and prices will force us to conserve) then we can squeak along. Past 2020 things will tighten more but that gives us way more than a decade to tweak our technologies.

We could car pool our way back to 2000 consumption levels.

Chevy is coming out with a new 'partial-electric' in 2010. Think about how much progress can be made in the subsequent 10 years if we are dedicated. (And we now are moving in the dedicated direction.)

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OK, memory fails me at this point. I'll go back and see what I missed.

[BobWallace]

At that point the EROEI number tells us that we should walk away from that well.

It doesn't even tell us that. If we have cheap energy from another source that happens to make bad fuel (say nuclear power or wind), we'll convert the cheap energy into good fuel at a loss and still make a profit. We might conceivably have windpowered stripper wells someday if we dont allready.

Energy return is a useless concept that confuses people without actually shedding any light. Its important when utilizing a new source of primary energy that its positive. Thats it. The rest is better determined by money or labor than energy accounting.

Good point. There are things that are best done with petroleum (at least at this point in our manufacturing processes). We might find it advantageous to use wind/solar to recover oil that wasn't feasible using oil for the extraction.

The whole EROEI thing makes sense if we're discussing whether it's worthwhile using oil to extract oil but it gets confounded when less expensive energy enters the market.

[BobWallace]

[You have built your argument on a ridiculous hypothetical. You said "if we have a cheap energy from another source . . . " Well we don't. Petroleum was that cheap energy that every other energy is dependent upon. Coal and uranium depends on trucks and railroads for transport. etc. No other fuel will propel this society. Maybe a different one. But not the one built and refined over the last 150 years.

Underground mining is basically all electric now. There is no reason why we couldn't surface mine with a combination of electric and biofuel. And raise the biofuel with electric tractors.

Railroads can be electrified. Some already are. Solar will be cheap. Solar can be used to create solar panels. All stages of solar production can be done using exclusively electric power. (Wind and tide will also be cheap.)

[pstarr]

Underground mining is basically all electric now.

and pneumatic as electric could ignite methane. But above ground is only partially electric and all mining delivers via truck or train which is diesel.

There is no reason why we couldn't surface mine with a combination of electric and biofuel. And raise the biofuel with electric tractors.

Railroads can be electrified. Some already are.

Solar will be cheap. Solar can be used to create solar panels. All stages of solar production can be done using exclusively electric power. (Wind and tide will also be cheap.)

I wish this were true but we are at the 11th hour and 59th minute and none of this has come to pass.

[whereagles]

]The idealised or "text book" Stirling cycle is a thermodynamic cycle with two isochores (constant volume)and two isotherms (constant temperature). It is the most efficient thermodynamic cycle capable of practical implementation in an engine - its theoretical efficiency equaling that of the hypothetical Carnot cycle.

That cannot be true. The Stirling cycle use isochores instead of adiabatics and therefore deviates from the ideal Carnot cycle.

http://en.wikipedia.org/wiki/Stirling_cycle

[davep]

As you can probably tell, I'm no engineer...

I've read that the Stirling cycle theoretically approaches the Carnot cycle more than any other real-world cycle, e.g. here

The differences between Stirling and the theoretical Carnot cycle elude me. If you could explain nice and slowly I may just get the gist

This link explains why Stirling is less efficient that Carnot "The reduction in efficiency results from the isochoric process where heat goes in but no work gets done.". It also states that Stirling is more efficient than Carnot as a heat pump, but less so as a refrigerator. I couldn't possibly verify the equations though.

[davep]

Anyway, getting back to EROEI, I was looking at various stirling patents (such as Dean Kamen's for the Segway), trying to get inspiration for an expedient stirling engine with lower costs, less exotic materials but decent design.

When looking at one of the patents for the segway stirling, I noticed that a lot of time was spent trying to improve the design of the hot end heat exchanger (this was an alpha stirling configuration btw). It suddenly came to me that they always have the heat exchanger as part of the cyclinder, thus increasing complexity and manufacturing difficulty.

For a solar stirling, it would be ideal to have both heat exchangers as separate entities from their respective cylinders, enabling a flat surface for solar collection, and simplifying the design of both the cylinders and the heat exchangers to boot.



So, in the above image, the heat exchangers would be either side of the regenerator.

The only downside appears to be that there would be a possible increase in dead gas volume, but given the potential decreased cost and higher efficiency of the heat exchangers, this seems a minor consideration.

This seems a simple and useful design concept, but I've never seen it in stirling engine design. Given that the gas doesn't need to expand in the cylinder itself, but on its way there, I don't see any theoretical reason why it couldn't improve cost and longevity of stirling engines in the solar market. The design would especially improve scalability of engine design, as the heat exchanger efficiency would not drop as the cylinder size increases.

[jbeckton]

20% increase in efficiency from coal or silica-based solar is not going to happen. There will be no more efficiency gains of that level burning fossil fuel, manufacturing solar panels, or utilizing the remaining energy we have.

Why?

Average efficiency today is only ~12%. Are you saying that it won’t reach 14.4% (20%gain)? Where are your references?

Each of the subcells can capture a different wavelength range of light, enabling each subcell to efficiently convert that light into electricity. With their conversion efficiency measured at 40.7%, the metamorphic multijunction concentrator cells surpass the theoretical limit of 37% of single-junction cells at 1000 suns, due to their multijunction structure.

Citation: King, R. R., Law, D. C., Edmondson, K. M., Fetzer, C. M., Kinsey, G. S., Yoon, H., Sherif, R. A., and Karam, N. H. “40% efficient metamorphic GaInP/GaInAs/Ge multijunction solar cells.” Applied Physics Letters 90, 183516 (2007). http://www.physorg.com/news99904887.html

Solar panels that cost less than $1 per watt to produce are on their way, as Colorado State University's new method for low-cost, high-efficiency solar panels looks set to begin mass production. The panels will be made by AVA Solar, and production should start towards the end of next year at a huge factory employing 500 people.

The cost reduction comes from the new, continuous manufacturing process which uses cadmium telluride thin film rather than the more expensive crystalline silicon. Once manufactured, the cost to buyers could be brought down to $2 per watt, which is roughly half the current cost of solar panels. http://www.treehugger.com/files/2007/09 ... y_week.php

So, the production costs and energy investment have dropped significantly, and the efficiency will increase ~300%. Please show me how this "minimally affects ERoEI".

[whereagles]

davep, don't worry about the equations. The bottom line is the Stirling engine has a nice and efficient cycle, though not as good as the ideal, Carnot, cycle.

[BobWallace]

Underground mining is basically all electric now.

and pneumatic as electric could ignite methane. But above ground is only partially electric and all mining delivers via truck or train which is diesel.

And the pneumatic power (air compression) is provided by electricity.

There is no reason why we couldn't surface mine with a combination of electric and biofuel. And raise the biofuel with electric tractors.

Railroads can be electrified. Some already are.

Solar will be cheap. Solar can be used to create solar panels. All stages of solar production can be done using exclusively electric power. (Wind and tide will also be cheap.)

I wish this were true but we are at the 11th hour and 59th minute and none of this has come to pass.

This "11th hour and 59th minute" stuff is just plain horse hockey.

If you're that paranoid or insecure please seek professional help.

We have waited longer than we should have. We will experience some hurt because we have waited so long. But get real.

Only a small percentage of our electricity is produced from petroleum. Oil could disappear and we could continue to play with our GameBoys (those of you who do) and the only hardship we would experience is having to change out our incandescents with CFS.

Twelve years from now (best prediction available) we will have as much oil as we had seven years ago. That means that over the next 12 years we will have to cut back a small percentage in our gas usage. Hybrids, smaller cars, and carpooling will get us there.

If you want to worry about something then worry about how people in dry parts of the world are going to get by as their summer surface water disappears along with the glaciers and winter snow packs. Think about where they might have to migrate.l

[slinky]

When I was in thin-film r&d, no two panels had the same efficiency, and efficiency decreased rather quickly. Different locations on just one panel yielded diffrent out put and efficiency degredation. The thin film you install today probably won't be as efficient in just a few years from date of install. Unless there has been some eureka/miracle improvement in thin film panel manufacturing.

Jeff