Urban agriculture: Another Win-Win for China?

china-ghos-town-half-built-structures-ayres

 

Report from China: Robert Ayres

In my last post I explained why (private) investment the automobile industry was a huge win-win for the US in the early years of the 20th century, for reasons that do not apply to 21st century China. In fact, there are strong arguments that the overall impact of still more cars (and highways) in China will be more nearly a lose-lose proposition, the only winners being the foreign auto manufacturers.

However, I think there is another investment opportunity, still in its infancy, that – if pursued intelligently – can be a true “win-win”.

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On EROI: Commentary by Professor Charles Hall

See “On EROI, as a measure of what’s left in the barrel” at http://wp.me/p55vqx-95

charles-a-s-hall-2Happy to see a website devoted to the (mostly) good ideas of Robert Ayres. As the originator of the term if not the concept of EROI I would like to clarify a few things from my own perspective. The energy invested is usually and appropriately considered the energy diverted from society to get energy to society. Thus natural gas used to pressurize an oil/gas field or energy used in society to make a drill bit or oil rig or fertilizer for corn-based ethanol would be considered part of the investment. Geological energy to make radioactive uranium or oil would not.

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On EROI, as a measure of what’s left in the barrel

RUA EROI

Source; Mason Inman. Scientific American. April. 2013. http://goo.gl/n57ZKG

This paper makes several points about the use of EROI as an indicator of future potential.

First, for comparability it is important to limit comparisons to specific end-use a products, such as gasoline for cars or electricity for the grid, or perhaps hydrogen for fuel cells. Comparisons between different end-uses are very dubious.

Second, it is important to avoid comparing EROIs for fossil fuels stored by geochemical processes in the Earth’s crust vs nuclear power (based on a single element, uranium) vs technologies based on energy directly or indirectly from the sun.

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