New Process Promises Ammonia From Air, Water, and Sunlight

The synthesis of ammonia is one of the globe's most significant industrial applications of chemistry. PhysOrg reports the publication in the August issue of Science (sadly, article is paywalled) the description of a low-energy process to syntheize ammonia for fertilizer using just air, water, and sunlight, by zapping with electricity water bubbling through a matrix of iron oxide, and sodium and potassium hyroxide. Electricity isn't free, though — "Low energy" in this case means two-thirds the energy cost of the long-in-use Haber-Bosch process. Researcher Stuart Licht is getting some of the energy to run this reaction from a high-efficiency solar cell he's created, which creates hydrogen as a byproduct. Along with the elimination of the need to produce hydrogen from natural gas, the overall emissions are reduced quite significantly. The whole process also takes place at milder conditions, not requiring 450C and 200 times atmospheric pressure as the Haber-Bosch process does. ... But even with Licht's method, [University of Bristol electrochemistry professor David] Fermin points out that we are far away from being able to replicate nature's efficiency at converting nitrogen from the air to useful chemicals, which is done by nitrogen-fixing bacteria. "What is truly remarkable is that nature does it incredibly efficiently at low-temperature," Fermin added. And yet, if something more efficient can replace the Haber-Bosch process, it would lower the energy input of the production of one of the worlds most important chemicals and lead to a notable reduction in global CO2 emissions.

Re:This could be great

[Anonymous Coward]

with the Haber process needing 450C temperatures and and 200 ATM pressure, I think your teacher was over-reacting. Anyone with the facilities to do that didn't need your teacher to help them

Re:Some background

[mdsolar]

"it would mean that the world could sustain its food production at current levels indefinitely" Sort of. We still need to get the effects of the faster nitrogen cycle under control. Right now, more corn means fewer shrimp as a huge dead zone develops in the Gulf of Mexico. The corn then feeds pigs in Pennsylvania and the nitrogen in the manure wrecks the oyster and crab harvest in the Chesapeake. All this can be fixed, but since one form of food production is stealing from another, the sustainability is in question for now.