دانلود رایگان مقاله انگلیسی سوخت های خورشیدی و القاء برگرفته از فتوسنتز - الزویر 2018

Abstract

The generation of renewable electricity is becoming increasingly cost-effective and efficient so that a different set of challenges have arisen that need to be overcome. The most pressing of these is the development of viable, ‘green’ ways to store this energy as carbon-carbon bonds. Natural photosynthesis provides a ready blue print for the conversion of solar energy into carbohydrate, i.e., a fuel composed of carbon-carbon bonds. Natural photosynthesis is too complicated and its components too fragile ever to be copied in an artificial context. Natural photosynthesis, however, does provide many templates that can be mimicked in any future bioinspired version of artificial photosynthesis, such as the oxygen evolving complex and the enzyme RuBisCO. Many options will need to be explored to find the best ways to achieve artificial photosynthesis and to achieve it will require a large-scale, coordinated international effort. There is simply no time left to continue in the way we are now. Climate change needs to be stopped as soon as possible and the clock is ticking for us to make clean, renewable solar fuels. We must all now work together!

3. Going forward

Recently Dan Nocera has used his understanding of both chemistry and biology to build a novel system that can use solar energy to drive the synthesis of a carbon-based fuel [42]. His prototype system starts with the splitting of water by electrolysis, powered by a solar cell and facilitated by catalytic, cobalt/phosphate electrodes for the oxygen evolution, and NiMoZn electrodes for hydrogen evolution. These electrodes reduce the over-potential required to drive the water splitting reactions and the cobalt/phosphate electrodes are self-healing. The hydrogen that is produced is then provided to the anaerobic bacterium Ralstonia eutropha where hydrogenases use it as a source of energy to drive the incorporation of CO2 into polyhydroxybutyric acid (PHB), a carbon storage product [43]. The overall energy efficiency for the incorporation of CO2 powered by the hydrogen is approximately 50%. This is an interesting system as it combines both the use of a solar cell to initially harvest solar energy with enhanced efficiency and the power of biology in the form of the enzymes to carry out the conversion of CO2 into PHB. With the advent of synthetic biology the ‘biological module’ in this set up can be changed and/or optimized to provide not just PHB but a wide range of other products. This example is also useful to illustrate what can be achieved in this area when different scientific disciplines (chemistry, physics and synthetic biology) are brought together to tackle the problem. Unfortunately, it seems clear that a lot of research under the umbrella of ‘artificial photosynthesis’ is rather fragmented, with too many people just doing what they always have done but now badging it as artificial photosynthesis. Researchers in this area need to come together, decide on an integrated approach and begin to work together across many disciplines, in a much more coordinated way, if we are to achieve an efficient, functional and applied form of artificial photosynthesis in time. There are a few current initiatives where this is taking place; UNICAT in Berlin, the CIFAR program on Solar Fuels in Canada and the Swedish Artificial Photosynthesis Consortium in Uppsala are good examples. However, the clock is ticking towards irreversible global warming and that means time is of the essence.