Motor vehicles are a major contributor to Climate Change. In the UK alone over 30 billion litres of petrol and diesel are consumed every year. It would be incredible if some day we could phase out combustion engines entirely and rely only on electrical vehicles, but aside from technological limitations, high costs, and cultural and political factors, there is another major issue that makes such a shift unfeasible in the short and mid term: our entire infrastructure is designed to accommodate gasoline guzzling and fume spewing cars. The requirements and the attributes of a system built around electric vehicles would be very different from what we currently have.
This doesn’t mean we should give up the noble goal of going all-electric in the future, or that we shouldn’t work on making the changes to our infrastructure that a post-petrol world will demand, but such a major shift on a global scale will likely take decades to accomplish and in the meantime we will need other solutions to help with the transition. One of these could be solar fuels, the resulting product of artificial photosynthesis.
What is artificial photosynthesis?
The sun blasts our planet with a quasi-unimaginable amount of energy every day, and we have only just begun to harness its potential. The reason fossil fuels are so convenient is that they are physical mediums that store energy in solid, gaseous or liquid form. This allows us to transport them, store them and transform them into other useful resources. In contrast, the electricity we generate with solar panels, windmills or hydro turbines is not as malleable. It is transferred from producers to consumers via the grid, but there are limitations to distance due to efficiency and our ability to store it effectively is limited. Energy storage is somewhat of a hot topic right now, with a myriad of companies promising to bring efficient electric storage to the home very soon, but what if we could actually capture the energy in sunlight in a physical form?
Replicating photosynthesis, the process by which plants use sunlight to transform carbon dioxide and water into energy, has long been a goal for scientists. Plants, algae and some forms of bacteria have been doing this for billions of years, and this process originates virtually all the energy that is consumed by living organisms on Earth. In a sense, the chain that ends with a steak and a salad on your table actually begins with the Sun.
In very simple terms, photosynthesis takes place when the chlorophyll located in plants’ chloroplasts captures sunlight and uses it to break down water and carbon dioxide, producing oxygen and glucose. The oxygen is released back into the air (this is the reason we have a breathable atmosphere) and the glucose is used by plants as nourishment, as well as by all the other organisms in the food chain. Now, scientists want to use the same process to produce biochemical fuels that we can use to substitute gasoline and other petroleum derived products.
Solar fuel: green methanol
One end product that has many potential applications is solar-driven methanol. Using energy from the sun we can split carbon dioxide and water into carbon, oxygen and hydrogen. These three elements can then be combined to produce green methanol.
In traditional terms, methanol is one type of alcohol fuel that can be used as alternative fuel in gasoline combustion engines. If it is used as low blend in gasoline, very little or even no modifications of the engine are needed. However, the whole point of having a clean methanol economy would be to create a greener society, so no syngas must come from fossil fuels. When methanol is produced by utilizing renewable sources such as solar the product is called green methanol or renewable methanol. A big advantage of green methanol over hydrogen is that is very safe (is not explosive).
The issue facing us now is how to manufacture it through artificial photosynthesis in a cost-efficient manner. The photosynthetic process renders all the base elements needed to produce methanol fuel, but it doesn’t do the work of combining them. The biggest challenge researchers are working on is finding a way to integrate these two processes, so as to be able to manufacture this fuel in an efficient and environmentally friendly way.
While green methanol burning vehicles will still produce pollution, there is a lot of potential in the technology because instead of burning fossil fuels and releasing the carbon within them causing a net carbon gain in the atmosphere, artificial photosynthesis could be coupled with carbon capture technologies to reverse that process – extracting harmful carbon from the air and using it to make fuel. This would mean that instead of constantly adding fresh carbon to our atmosphere we could reuse the carbon that’s already there and transform it into fuel.
Replicating plants with artificial leaves
The Joint Center for Artificial Photosynthesis (JCAP) is at the forefront of research in the discovery and development of artificial photosynthesis technologies. It is a collaborative enterprise between various universities, with its primary facility located at Caltech in California.
Just a few months ago JCAP published a paper detailing their first successes in producing what they have termed ‘artificial leaves’, an electrical conductive film that replicates the process plants perform in photosynthesis, transforming water and carbon dioxide into the elements of oxygen, hydrogen and carbon, which can be used to produce green methanol.
So far the lab results for this technology have been very positive, and now the challenge facing researchers is finding ways to scale it to a level where it is efficient and economically viable as an energy source for our societies.