a spectacular scientific achievement

by swapna Sat Sep 24, 2016 11:18 am

finally, artificial photosynthesis!

http://www.scientificamerican.com/article/bionic-leaf-makes-fuel-from-sunlight-water-and-air1/

daniel nocera, a chemist, had been working on the invention for six to ten years, first at m.I.t., then at harvard. three years ago, his lab at m.i.t. was able to generate hydrogen electrochemically from sunlight and water, using a special catalyst, a.f.a.i.k., without additional energy inputs.

after moving to harvard about three years ago, nocera has collaborated with pamela silver, a biologist at harvard medical school. her lab invented the second-stage biological process in which specially-synthesized microbes combine the hydrogen with atmospheric co2 to form liquid fuels like isopropyl alcohol.

the resulting "bionic leaf," outwardly, mostly a glass jar (with valuable "stuff" - electrodes, catalyst - immersed in the water held in it), I think, achieves an (energy?) efficiency of 10%, whereas the natural leaf achieves only a 1% efficiency!

(I don't know how that efficiency is defined. it could be the heat of combustion of the liquid fuels formed divided by the amount of solar energy falling on the apparatus.)

this is a triumph of the synergy of electrochochemistry and microbiology, a paradigm for twenty-first century science.

it will probably take ten years of engineering development to turn this invention into reliable equipment and plant for routine use. the potential is enormous.

there should be at least one nobel prize in the work leading to the nocera-silver bionic leaf.

by MaxEntropy_Man Sat Sep 24, 2016 11:35 am

mimicking photosynthesis at higher efficiencies than nature is indeed very exciting. thanks for posting this. efficiency is certainly very important. the bottle neck in such processes however is usually the rate, which is at present is impractically small compared to state-of-the-art electrolyzers or industrial processes such as steam-methane reformation. and the reason is the usual arrhenius bottleneck -- you have thermodynamics working in your favor, but the kinetic barrier known in chemical kinetics as the activation energy barrier is too large to be overcome using room temperature thermal energy. a possible solution is to try and do this at higher temperatures, but unfortunately the bacteria will probably not survive higher temperatures.

by garam_kuta Sat Sep 24, 2016 1:04 pm

MaxEntropy_Man wrote:mimicking photosynthesis at higher efficiencies than nature is indeed very exciting. thanks for posting this. efficiency is certainly very important. the bottle neck in such processes however is usually the rate, which is at present is impractically small compared to state-of-the-art electrolyzers or industrial processes such as steam-methane reformation. and the reason is the usual arrhenius bottleneck -- you have thermodynamics working in your favor, but the kinetic barrier known in chemical kinetics as the activation energy barrier is too large to be overcome using room temperature thermal energy. a possible solution is to try and do this at higher temperatures, but unfortunately the bacteria will probably not survive higher temperatures.

can't the thermophilic ones of the yellowstone variety survive?

by Vakavaka Pakapaka Mon Sep 26, 2016 12:08 am

Just imagine what would have happened if such an experiment was attempted during the time of Da Vinci, Galileo or Copernicus. Then gowns would have hunted them down.......

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