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

[Micki]

The question is almost philosophical as we don't know what technological advances there may be.

Secondly, what I have found a bit disappointing is all this talk about cheap solar panels etc being developed, but I just can't seem to find them. So what ever development that aleary has been done, it look tome like it hasn't hit the market.

[cephalotus]

As for solar, I have tried to read about the industry for my investments. I have tried to understand where the costs are heading and whether the industry has a long term future. The current solar panels are made of silicon which requires high tech companies like AMAT to be involved. It is similar to making semiconductor chips. Very energy intensive. The theoretical max efficiency of silicon solar is 30% of eneregy conversion. The real practical limit is about 25%.

yes.

There is a breakthrough I read about that raises the theoretical limit to 70% energy efficiency and practical application are in the 45% to 50% range. But that is a few years away.

no. 70% (or even 50%) is not possible with Si cells and sun light. That's against the know law of physics. (you can not use all of the energy of the photons to create electrons, very simplified...)

The 2nd generation is considered to be the new thin film solar panels made by First Solar (FSLR), Energy Conversion Devices (ENER), etc. These are much cheaper and flexible. They use 1% of the silicon compared to others.

First Solar uses CdTe, not a-Si. I don't know about ENER, I have read their name first here.

But the efficiency is lower. 8% to 10% of energy converted. But the dramatically lower cost makes the lower energy conversion ratio worth it.

It's said, that First Solar has the / one of the most cost efficient production processes at the moment. But you have to add additional cost for the bigger mounting system (aluminium and copper gets more and more expensive) and for their recycling system. They will (have to) take back defective modules because of the Cd.

These are being built into things like roof shingles. These companies are selling out of their inventory years in advance

...
not years. Maybe weeks.

The next generation is companies like NanoSolar. It is not yet public, but the founders of Google are major backers of one. Their technology is taking the efficiency of thin solar to the next level. I forget the details though.

the usual blabla. Use the word "nano" and many people will get crazy. Maybe they will introduce a real product, after taht it is worth to discuss.

So in summary, I do believe that the EROEI is improve dramatically for solar. The capital costs are dropping for building these newer solar panels. If there are lower capital costs, odds are that this translates into less energy consumed to produce the solar panels.

? It's said that production cost shrinks at about -8% to -10% per year at the moment. That's an average amount, of course.

[pstarr]

cephalotus is right. Whenever you see nano or biotech you need to think blah blah blah I am a sucker investor wannabee looser but really I am a looser sheeple who is dumb enough to think I can beat the system. dumb.

Energy Return On Energy Invested is a measure of the net energy produced by a primary energy source. Every power system (other than the sun and plants) must be designed, prototyped, tested, implemented, managed, maintained, sold, installed, operated, produced, and hyped forever. This takes what? ENERGY. unlike plants which just make pollen and reproduce.

give it up. there is no free lunch. the party is over. goodnight.

[jbeckton]

cephalotus is right. Whenever you see nano or biotech you need to think blah blah blah I am a sucker investor wannabee looser but really I am a looser sheeple who is dumb enough to think I can beat the system. dumb.

They used to say the same thing about micro a few years back, I guess your portfolio missed out on that ride?

[whereagles]

I seem to detect a problem with silicon-based solar power.

I dunno how well the world is stocked of silicon ore, but it might happen at some stage that we're going to have problems getting raw silicon.

Since the earth's crust is made basically out of silicon dioxide (SiO2), we could try and split the two elements. But does this operation have EROEI > 1? In other words, does a solar panel produce enough energy during its lifetime to sustain production of another (replacement) panel?

[davep]

I'm not sure if photovoltaics are the best bet for EROEI. Surely thermal solar is better?

And for cheaply (in the energy required sense) producing electricity over a long period of time, solar troughs or parabolic dishes attached to a rankine or carnot cycle engine appears a better bet in the long term.

[jbeckton]

I'm not sure if photovoltaics are the best bet for EROEI. Surely thermal solar is better? And for cheaply (in the energy required sense) producing electricity over a long period of time, solar troughs or parabolic dishes attached to a rankine or carnot cycle engine appears a better bet in the long term.

What is a carnot cycle engine? It's hard to put any weight into current EROEI of a developing technology because production costs are high for new technology which makes your Energy Invested run high, and the efficiencies are low which lowers your Energy return run low.

You end up with a distorted number. You need to look at what the EROEI would be after the technology is fully developed. Hence, the title of the thread.

[davep]

I'm not sure if photovoltaics are the best bet for EROEI. Surely thermal solar is better? And for cheaply (in the energy required sense) producing electricity over a long period of time, solar troughs or parabolic dishes attached to a rankine or carnot cycle engine appears a better bet in the long term.

What is a carnot cycle engine? It's hard to put any weight into current EROEI of a developing technology because production costs are high for new technology which makes your Energy Invested run high, and the efficiencies are low which lowers your Energy return run low.
You end up with a distorted number. You need to look at what the EROEI would be after the technology is fully developed. Hence, the title of the thread.

From Wiki:

The Carnot cycle is a special type of thermodynamic cycle. It is special because it is the most efficient cycle possible for converting a given amount of thermal energy into work or, conversely, for using a given amount of work for refrigeration purposes.

The engine that can best approach the theoretical carnot limit is the stirling engine, that uses a "regenerator" between the hot and cold heat exchangers, in order to reuse some of the heat/cold before getting back to the heat exchanger. And rankine engines are hardly at the cutting edge of technology. They may be theoretically less efficient, but they're proven.

[jbeckton]

And rankine engines are hardly at the cutting edge of technology. They may be theoretically less efficient, but they're proven.

I usually think of carnot as the max efficiency between 2 temps but the way you worded it:

attached to a rankine or carnot cycle engine appears a better bet in the long term.

implied that rankine and carnot were 2 types of engines rather than one being the "perfect' version of the other. I have never heard of a carnot cycle engine. It is impossible to achieve so it is only used as a standard with which we can compare actual engines. The process can use a rankine cycle (or other cycle), but not at carnot efficiency.

[davep]

The process can use a rankine cycle (or other cycle), but not at carnot efficiency.

I see. I guess I should have said Rankine or Stirling cycle. Although the latter is potentially the best embodiment of real-life carnot efficiency, it doesn't strictly use a carnot cycle.

[jbeckton]

The engine that can best approach the theoretical carnot limit is the stirling engine, that uses a "regenerator" between the hot and cold heat exchangers, in order to reuse some of the heat/cold before getting back to the heat exchanger.

A rankine cycle can also use a regenerator. A coal power plant bleeds off steam from the turbines to heat the water up before it gets to the boiler.

We also use cogeneration, where we take steam from the boiler and use it to power turbine driven boiler feed pumps.

[davep]

A rankine cycle can also use a regenerator. A coal power plant bleeds off steam from the turbines to heat the water up before it gets to the boiler. We also use cogeneration, where we take steam from the boiler and use it to power turbine driven boiler feed pumps.

Fair enough. But overall, the Stirling cycle has the most potential, theoretically:

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. However technical issues limit its efficiency when applied - for instance a simpler mechanism may be favored over attaining a close fit to the theoretical cycle.

[BobWallace]

Energy Return On Energy Invested is a measure of the net energy produced by a primary energy source. Every power system (other than the sun and plants) must be designed, prototyped, tested, implemented, managed, maintained, sold, installed, operated, produced, and hyped forever. This takes what? ENERGY. unlike plants which just make pollen and reproduce.

give it up. there is no free lunch. the party is over. goodnight.

There is energy invested in the creation of the "first set" of PV panels. The "first set" is the number of panels required to power future panel creation. Enough panel power to scoop up the sand, extract the silicon and aluminum, ....

We use some of our existing oil/hydro/coal/whatever to make those panels. That's our energy investment. Or "EI".

Once we've made enough panels to power the extraction, fabrication, transportation, installation, and maintenance of future panels we have moved into free-lunch-land. From that point on all our energy out, or "EO" requires no further investment.

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.

[pstarr]

cephalotus is right. Whenever you see nano or biotech you need to think blah blah blah I am a sucker investor wannabee looser but really I am a looser sheeple who is dumb enough to think I can beat the system. dumb.

They used to say the same thing about micro a few years back, I guess your portfolio missed out on that ride?

Actually Jbecton I am referring to specifically to energy (and to a lesser degree agriculture systems.) Neither nano nor biotech will play any role in avoiding or mitigating PO. Thinking otherwise is techtopian nonsence.

While it is true that biotech fermentation systems have a place in the pharmaceutical factory, biotech is agriculturally suspect, probably a complete failure, most certainly nothing but an insignificant band aide. While Bt and herbicide-resistant crops make some big company money, they are merely a symptom of petroleum-agriculture decline. Bt corn plants are poisonous from the root to the tassle and herbide-resistant crop are already loosing resistance.

As for nano, the definition needs to be ironed out before you can call any application a success unless you believe solid-state circuits and buckyball graphite lubricants will be fashioned into petroleum.

[pstarr]

There is energy invested in the creation of the "first set" of PV panels. The "first set" is the number of panels required to power future panel creation. Enough panel power to scoop up the sand, extract the silicon and aluminum, ....

We use some of our existing oil/hydro/coal/whatever to make those panels. That's our energy investment. Or "EI".

No. this is not 'EI.' What you describe is the one-time petroleum subsidy we may perhaps use to transition to a steady-state solar economy. It has nothing to do with industrial life-cycle energy analysis that leads to EROEI measures.

Once we've made enough panels to power the extraction, fabrication, transportation, installation, and maintenance of future panels we have moved into free-lunch-land. From that point on all our energy out, or "EO" requires no further investment.

We are in the process of eating up what is left of our free lunch---the petrified salad called petroleum.

You seem certain that we will build enough solar panels and wind mills to mine ever-decreasing quantities and qualities of essential ores. How many windmills will it take to to mine, crush, and smelt iron? I am not even confident that solar energy systems have a positive energy return. I see numbers bandied about like 8:1 but I have never seen the studies.

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. It will always take xxx units of electricity to build a windmill that will gather yyy units of wind. If there is a positive eroei then we can eventually manufacture more and more windmills but the propagation remains the same, though the rate of increase could be described as exponential.

[jbeckton]

As for nano, the definition needs to be ironed out before you can call any application a success unless you believe solid-state circuits and buckyball graphite lubricants will be fashioned into petroleum.

I know your view of this alchemy , just wanted to stir your pot.

I hope you are around when nano starts to take off.

It will be good fun to hear why it won't matter, rather than it is not possible...

[BobWallace]

When the concept of "energy invested" is used it is in terms of the energy sources that we have readily at hand at the moment.

The problem of retrieving more oil from "played out" wells is that as we extract more and more oil from those wells it takes more "oil supplied" energy to get that oil. We go from "easy oil" where we might get four barrels via the use of one barrel to the point where it can take more than a barrel of energy to extract a single barrel.

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

The same concept applies to coal and hydro. We reach a point where we have to expend more energy than we get.

Not so with solar panels. Energy from the sun is readily available and essentially unlimited in time frame. (I'm not going to worry about what folks are going to do 5 billion years from now. Call me callous if you will....)

What holds for solar holds for wind, wave, and tidal as well. Once we create enough ability to harvest the "free" energy sitting there we are no longer investing "energy" in the sense that the term is used. Oil/coal gets us the startup and after that the devices provide the additional power for (essentially) nothing.

--

Will we create new harvesting devices rapidly enough?

Obviously not. We should have had these technologies up and going long ago.

If we had we wouldn't be experiencing the global warming, pollution, and political/war problems that are now harming us.

Will we create new harvesting devices rapidly enough to prevent further misery?

Probably not. People at the bottom of the economic ladder are going to get hurt.

Will civilization crash and burn?

Don't be silly.