Solar cells: Artificial photosynthesis - A solution to the energy problem?

From exploring swarm dynamics in insects to inform the design of intelligence and communication systems, to observing how a fish swim to develop robotics; humans can learn a lot of things from nature. Most notably, rapid technological developments in the field of biomimetics seek to imitate nature to solve many problems, including the energy problem (Gross, 2014).

What is a solar cell?

Solar cell technologies (e.g. photovoltaics etc.), seek to harness energy from the sun. It is basically an electronic device, which directly converts solar energy into electricity. Light shining on the solar cell produces both a current and a voltage to generate electric power (REDARC Solar, 2014).

For more click here >>> http://pveducation.org/pvcdrom/solar-cell-operation/solar-cell-structure <<<

We know about solar PV already (from my last post), so what's the thinking all about then? 

http://cheme.nl/ce/people/jara.html

Of course, you might have guessed already….let’s use solar energy to make fuels! The whole idea seems like a dream but great news, we're on the right on track already. This is what the solar cell and more specifically, artificial leaf technology aims to do. 

Think like a leaf! 

Plants transform light energy into chemical energy. By drawing energy from the sun, natural photosynthesis proceeds through a series of important chemical reactions, such as the oxidation of water to molecular oxygen and the decomposition of carbon dioxide into the form of sugar or fuel (Marshall, 2014).

Artificial photosynthesis is an exciting research area that focuses on mimicking the process of photosynthesis. 

However, the leaf is a complex system and cannot be replicated exactly. Instead, researchers are using leaves as inspiration to develop something new.

Let me explain.

The Artificial Leaf

The artificial leaf is the product of Daniel Nocera's, a professor at the Massachusetts Institute of Technology, goal of achieving a practical energy source (Nocera, D.G., 2011).

http://www.nanotechetc.com/2013/06/artificial-leaf-uses-photosynthesis-to-supply-energy/10131.html

An artificial leaf is a light-driven stand-alone device, with H2 and O2 catalysts, that takes up water and splits it into protons and electrons to generate hydrogen (Joya et al, 2013, Nocera, 2011). 

  Van Noorden et al (2011) - Nocera

http://www.nature.com/news/2011/110929/full/news.2011.564.html

http://www.dailytech.com/Researchers+Manage+to+Store+Solar+Energy+as+Hydrogen++But+Only+1/article34141.htm

Through the artificial photosynthesis process, scientists aim to harvest sunlight to chemically convert H2O and CO2 into two solar fuels namely, hydrogen fuel and carbon-based fuel e.g. methanol (Hammarstrom and Hammes-Schiffer, 2009).

The solar-to-fuel conversion is conducted by water splitting. This is viewed as an attractive and accessible way to proceed for a solar-driven water splitting, using an artificial leaf to produce renewable fuels (Joya and Groot, 2013). 

What's pretty cool is that hydrogen can be combined with a suitable CO2 reduction module to generate liquid fuels, e.g. formic acid or methanol (Joya et al, 2013).

[YOUTUBE] - 

The Artificial Leaf - Renewable Energy - Horizons

https://www.youtube.com/watch?v=J556uXwrjII

Impressive eh?

 Michael Gross reported in a recent article that, “advances in photosynthesis research may help to find new ways of reconverting carbon dioxide into fuel, which would solve several global problems at once.” Welcome to the artificial leaf project! 

One example of recent efforts is the Joint Center for artificial photosynthesis (JCAP), which is most famous for its work on artificial solar-fuel generation technology. The center is one of many centers tackling the main challenge of finding the most cost-effective method to produce fuels from sunlight, water and carbon dioxide.

Artificial photosynthesis: A solution to the energy problem??

The most promising aspect to artificial photosynthesis is the prospect of making hydrogen and other renewable fuels from this technology.

 Nocera was one of the first to make an unsupported device that could split water from sunlight and produce hydrogen and oxygen.

“Sunlight has the greatest potential of any power source to solve the world’s energy problems, in one hour, enough sunlight strikes the Earth to provide the entire planet’s energy needs for one year” said Daniel Nocera, a chemist at the Massachusetts Institute of Technology, cited by Ojo and Thomas (n.d.).

There are drawbacks though! 

A major obstacle to pursuing a solar-to-fuel- conversion water-splitting device is the development of a robust and long-living water-oxidation catalyst (Joya et al, 2013) .

Materials used in the artificial photosynthesis corrode in the presence of water, making them less stable over long periods of time (Listori et al, 2009).

Many catalysts often degrade quickly or they don’t produce the same output as a more organic catalyst (Ojo and Thomas, n.d.). 

Also, catalysts (e.g. platinum) are expensive and in order to make the technology cost-effective, scientists are searching for alternatives. 

Other concerns include:

- The quality of the fuel cell itself 

- Materials 

- Stability 

- Solar-to-hydrogen conversion efficiency

 The artificial leaf is still in its infancy and therefore, it is not yet applied at the commercial-scale. 

I think the concept of biomimetic photosynthesis (i.e. artificial leaf) is a creative proposal for energising the future, but to make a significant contribution to the energy sector, the technology has to become more efficient in terms of solar-to-hydrogen conversion and also, more economical. 

So, I come to some questions: 

Do we need a global artificial photosynthesis project? 

Do we need to invest in this technology? 

It is unlikely that we will see this technology disseminated into the commercial sphere any time soon. So, you could argue that it would not be a viable solution to the energy problem. 

There are those who argue the opposite, that artificial photosynthesis is actually an appealing strategy for producing sustainable fuels. 

I think this is dependent on whether we can find the right materials to make the technology work efficiently (Faunce, 2012).

In fact, there is rapid development towards a low-cost solar cell. 

Fast improvements in efficiency in the solar-to-hydrogen conversion is demonstrated by several recent studies. For example, a recent study by Luo et al (2014) claimed to have achieved water photolysis at 12.3% efficiency via perovskite photovolataics and other earth abundant catalysts. For more, click here.  

This is a massive improvement from Liao et al (2013) where solar water-splitting using a nanocrystalline Cobalt(II) oxide (CoO) photocatalyst had a solar-to-hydrogen efficiency of ~ 5%.  

CHECK THIS OUT: >>> http://www.youtube.com/watch?v=hkGAqk-TXw8 <<<

Is it worth investing? Provided that we find the best materials, which can only come about with research and development (R&D) investments, the artificial leaf shows particular promise as an inexpensive source of electricity for homes in developing countries. It is however still in the research/pilot phase and only a global project would fulfil the vision of powering homes from the sun in remote regions. 

“We are at the peak of the oil age but the beginning of the hydrogen age. Anything else is an interim solution. The transition will be very messy, and will take many technological paths .....but the future will be hydrogen fuel cells.”

Herman Kuipers, Manager of Exploratory Research

Royal Dutch Shell

I think that there is a lot happening in solar fuel technology, but the setbacks are the material costs. 

The technology is still in the early phase of development, so implementation soon looks highly unlikely, unless it is made into a global project. There are also issues relating to the cost-effectiveness and how long the technology lasts for. Making the technology commercially competitive remains a major challenge.

In essence, this demonstrates that the energy problem is truly a real-time experiment. 

For those in London, you don’t have to look far for an artificial leaf project. There’s one at Imperial College London, and some solar fuel cell work at University College London.

“Do we need a global project on artificial photosynthesis?” What do you think? If we do not know the impacts of artificial photosynthesis and efficacy in terms of substantially reducing CO2 emissions, is it better to invest in something else instead?

This has been debated already: https://royalsociety.org/events/2014/artificial-photosynthesis-global-project/

Let's wait and see. 

Lots of stuff here: 

Tachibana, Y., Vayssieres, L., & Durrant, J. R. (2012). Artificial photosynthesis for solar water-splitting. Nature Photonics, 6(8), 511-518.

Ojo, A., & Thomas, K.  (N.d.) ARTIFICIAL PHOTOSYNTHESIS: THE SOLUTION TO AN ENGERY PROBLEM.

Joya et al (2013) Water-Splitting Catalysis and Solar Fuel Devices: Artificial Leaves on the Move

Chuan and Hoque (2014) Engineering and Biomimetics: Harnessing Light Energy for Sustainability

necessity of harnessing alternative renewable sources of energy that focuses on sustainability and efficiency

Hammarstrom L, Hammes-Schiffer S (2009) Artificial photosynthesis and solar fuels, Accounts of chemical research 42: 1859-1860.

Nocera, D.G. (2011) The Artificial Leaf. [pdf]. Available at: http://www.nokemi.se/wp-content/uploads/2013/02/WendtOla_Nocera-l%C3%B6v.pdf (Accessed: 30 December 2013)

http://www3.imperial.ac.uk/energyfutureslab/research/grandchallenges/artificialleaf

http://www.nature.com/polopoly_fs/1.15341!/menu/main/topColumns/topLeftColumn/pdf/510022a.pdf

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3627107/

http://www.degruyter.com/view/j/green.2013.3.issue-1/green-2013-0007/green-2013-0007.xml

Faunce, T. (2012). Nanotechnology for a Sustainable World: Global Artificial Photosynthesis as Nanotechnology's Moral Culmination. Edward Elgar Publishing.