by kublikhan » Sun 27 Dec 2015, 11:47:15
$this->bbcode_second_pass_quote('Plantagenet', 'I') agree that the EROEI of renewables is currently too low---but things are changing quickly for the better on this front. The EROEI is not a static number---its getting better and better for renewables.
+1
Also renewables, like FF, have many different EROEI values depending on the specific renewable or FF you are talking about. Hydro, the largest renewable with the best
EROEI of renewables, has an EROEI better than the best EROEI FF: coal. Wind, the 2nd largest renewable, has an EROEI better than the oil and gas currently have. While solar's EROEI has been getting better at an exponential rate. Some of these renewables have a better EROEI than the fossil fuels used to make them.
$this->bbcode_second_pass_quote('', 'I')f current rates of improvement hold, solar power will be incredibly cheap by the time it’s a substantial fraction of the world’s electricity supply. Electricity cost is from now coupled to the ever-decreasing price of technology. That is profoundly deflationary and disruptive. It’s now fairly common knowledge that the
cost of solar modules is dropping exponentially. I helped publicize that fact in a 2011 Scientific American blog post asking
“Does Moore’s Law Apply to Solar Cells?” The answer is that something like Moore’s law, an exponential learning curve (albeit slower than in computing) applies.
The IEA (International Energy Agency), in one of its scenarios, projects
4 cent per kwh solar by mid century. Fraunhofer ISE, the German research institute, goes farther, predicting
solar as cheap as 2 euro cents per kwh in the sunniest parts of Europe by 2050. If this holds, solar will cost less than half what new coal or natural gas electricity cost, even without factoring in the cost of air pollution and carbon pollution emitted by fossil fuel power plants.
$this->bbcode_second_pass_quote('', 'I')f the Input energy is fossil fuel based the EROEI analysis will tell you how efficient the energy extraction process is with respect to energy use, and therefore how much energy ultimately can be extracted. If, however, the input energy is renewable even if the energy conversion process is seemingly inefficient in at the end of the process one has in total more energy than one started, which is quite the opposite from when the input was fossil fuel based.
Once you move from an entropic system (where energy flows from a highly concentrated state to a less concentrated state) to a negative entropy system (where you capture some form of diffuse solar energy and concentrate it) everything changes. Instead of running down finite energy sources you are now adding to the quantity of energy available. There will be other limits, but not energy per se. In a system relying on non-renewable energy, no matter what your EROEI is eventually you'll run out of fuel.
If humanity wants to continue to exist in a form recognizable to us making the switch from an entropic energy supply to a negative entropy energy supply is unavoidable. Without making that switch the game will be over at some point. We are starting to feel the first hints of limits to growth along a number of vectors, both on the input side as well as the output side of economic activity. Specifically, what you're seeing now is that there is a tension between a financial system which requires growth to exist and a natural system (resources) which naturally deplete and which have an extraction rate which at some point can no longer be increased. Switching to a negative entropy energy system would be an important step towards dealing with this problem.