Even just five years back, not many people knew that you could produce electricity from sunlight. Today, ‘solar’ is pretty much mainstream; most people of the world are sensitised to it. The buzz around solar is loud. You might go so far as to say that ‘solar’ is having its day in the sun.
However, ‘solar’ usually brings to the mind rows and rows of blue-grey panels facing the sky, producing electricity. So fast has been the growth of solar generated electricity that the fact that you can do other things with sunlight has escaped into the darker parts of our consciousness. Yet, once in a while, somebody comes up with something, and the awareness surfaces.
Fertilisers from sunlight
From sunlight, you can produce electricity, you can extract some heat, and you can trap the Sun’s energy in some crops, such as corn, and turn the agricultural produce into biofuels. But did you know that you can produce fertilisers using sunlight?
Ammonia is a key fertiliser — it contains nitrogen. Nitrogen is one of the three major soil nutrients, the other two being Phosphorous and Potassium. Ammonia is the widest-used nitrogenous fertiliser and is a compound of nitrogen and hydrogen.
The vexing thing about making this compound is the money and energy you need to spend in getting nitrogen to overcome its reluctance to join hands with hydrogen. (Or, for that matter, with any other element. Nitrogen is pretty inert and prefers to keep to itself, though not as introverted as the ‘royal gases’ — helium, argon or neon.) Fertiliser companies need to use a lot of heat and pressure, literally, to marry each atom of nitrogen to three of hydrogen.
NREL research
Now, scientists at the National Renewable Energy Laboratory, US, have come up with an easier way to convince the reluctant bride. How? Yes, you guessed it. By using sunlight.
How they do it is pretty technical. (Those who are really eager to know may look up this resource: http://goo.gl/6JACXi). Basically, it involves using nanotechnology to harvest sunlight and using the light energy to improve chemical reactions.
Bacteria take their energy needed to convert nitrogen into ammonia from the energy-storage molecules called ATP (which, by the way, are the molecules in our cells that store the energy we obtain from our foods.) The scientists demonstrated using sunlight to give the reactions a pep.
Ammonia as a store
The bottomline of this discovery is that solar energy can be stored as ammonia or, to put it conversely, using ammonia as a store of energy. (Indeed, the NREL research opens up exciting vistas of science — using sunlight to catalyse chemical reactions and who knows what mind-boggling applications this may lead on to?)
You can do many things with ammonia, even apart from fertilisers. You can, for instance, make explosives — but you can also use ammonia as automotive fuel.
And what is better than making ammonia using only sunlight and some bio-chemicals, a process that is clean and produces no carbon-dioxide, unlike the present method of producing the chemical fertiliser?