Exploring Hydrocarbon Depletion
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HydroLuver wrote: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%.
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.
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.
But the efficiency is lower. 8% to 10% of energy converted. But the dramatically lower cost makes the lower energy conversion ratio worth it.
...These are being built into things like roof shingles. These companies are selling out of their inventory years in advance
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.
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.
pstarr wrote: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.
davep wrote: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 wrote: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.davep wrote: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.
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.
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.
davep wrote:And rankine engines are hardly at the cutting edge of technology. They may be theoretically less efficient, but they're proven.
attached to a rankine or carnot cycle engine appears a better bet in the long term.
jbeckton wrote:The process can use a rankine cycle (or other cycle), but not at carnot efficiency.
davep wrote: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.
jbeckton wrote: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.
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.
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.
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.jbeckton wrote:pstarr wrote: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?
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.BobWallace wrote: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".
We are in the process of eating up what is left of our free lunch---the petrified salad called petroleum.BobWallace wrote: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.
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.BobWallace wrote: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 wrote: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.
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