Artificial Photosynthesis to Power the Future
At the launch of the Breakthrough Energy Coalition in November 2015, Bill Gates said, “If it works, it would be magical.”
What sort of “magic” was Bill Gates talking about?
He was talking about harnessing the power of the sun. But not in the way you might think, such as with solar panels. Gates was speaking about the potential for artificial photosynthesis.
Photosynthesis and Energy
We’re all familiar with photosynthesis from our high school science classes. It’s the process in which green plants use sunlight to convert water and carbon dioxide into oxygen and carbohydrates. These carbohydrates are the precursors of sugar and starch.
Humankind already takes advantage of photosynthesis to produce energy – in the form of biofuels.
But natural photosynthesis isn’t energy-efficient, converting only about 1% of sunlight into fuel. After all, the main purpose of natural photosynthesis is to sustain plants, so 1% is enough.
But what if we could make photosynthesis more energy-efficient?
Think about it… We could use water and a greenhouse gas – carbon dioxide – and convert them into the fuels we need. At the same time, we could reduce CO2 levels.
That’s the whole idea behind artificial photosynthesis. It sounds simple enough – use sunlight to split water and carbon dioxide into hydrogen, oxygen, and carbon. Adding a catalyst can then turn them into a fuel, such as methanol.
But the key, of course, is efficiency.
And that has made artificial photosynthesis a tough nut to crack. Scientists have actually been working on this since the 1970s – with little success.
Artificial Photosynthesis Projects
However, a number of recent breakthroughs offer promise.
Scientists at the California Institute of Technology created a lab-scale device that converts 10% of the sunlight received into fuel.
Other researchers at the Lawrence Berkeley National Lab and the University of California at Berkeley say they’ve created a system that can capture carbon dioxide emissions before they’re released into the atmosphere and convert them directly into fuels.
Their system uses an array of tiny silicon and titanium oxide wires studded with a bacteria – sporomusa ovata.
The nanowires capture sunlight and deliver it to the bacteria, which in turn convert CO2 into acetate. Acetate is a key building block for more complex organic molecules.
The efficiency of the system, however, is currently only 3%.
More promising is research from Monash University in Melbourne, Australia that’s focusing on generating hydrogen for fuel cells.
Their process closely mimics natural photosynthesis, using solar energy to convert water into hydrogen and oxygen. One key difference between them and the others, however, is that instead of using expensive precious metals as a catalyst, their method uses common (and cheap) nickel.
And energy efficiency came in at an impressive 22.4%. The prior record was 18% efficiency.
The Future of Artificial Photosynthesis
The drawback in my eyes about the Monash system and other similar projects is that the world just isn’t set up for a hydrogen economy yet.
The researchers – such as at Berkeley – who are adding in CO2 may be on the right path. Creating liquid non-hydrocarbon fuels to replace polluting hydrocarbon fuels seems to be the way to go. An added benefit is that this may create a market for captured CO2 from power plants and industrial operations.
The Joint Center for Artificial Photosynthesis – a collaboration between five California research institutions – is switching its focus to fuels.
But who knows what twists and turns science may take. Both paths should be pursued.
The good news is that the research and experimentation is rigorous at the moment.
Even the oil companies are getting involved. Both Total S.A. (TOT) and Royal Dutch Shell Plc (RDS-A) are part of the Solar Fuels Institute at Northwestern University. And industrial powerhouse Siemens AG (SIEGY) is working with universities in Germany and Switzerland to find the perfect catalyst to produce fuels.
Let’s wish them luck and hope at least one of them produces “magic.”