complex, perhaps emergent properties of enzymes and figuring out how to take advantage of those in the energy applications.

James Liao agreed that isolating enzymes from one organism and inserting into a foreign organism is a solved problem for the most part. He said that there is plenty of evidence of this in the current literature. However, he said that most people only demonstrate that the insertion produces a few micrograms or milligrams and call that a success. He said a microgram or milligram quantity is not going to burn in someone’s engine. The real challenge is not to just show an enzyme can be made, but that it can be done in a high-flux way. There needs to be a goal of more than discovering enzymes and expressing them in different organisms. Consideration also needs to be given to throughput and scale.

Photosynthesis and Energy Storage

Photosynthesis was discussed as the main source of sustainable energy for the future. Judy Wall said that there are three main issues with photosynthesis: harvesting the energy, storing the energy, and converting the energy. For harvesting, photosynthesis works well for nature’s purposes, but it is not as efficient as it could be for engineering devices for human needs. This is because Earth is not limited in light, for the most part, so it does not have to be particularly efficient. Thus, there is room to improve efficiency of the system.

Photosynthesis also presents a biological contribution to energy storage. The primary approach to energy storage is batteries. One problem is that current battery technology depends a lot on rare earth elements. James Liao added that the battery is also not a highly efficient storage material because the energy density is low. However, he said that it appears that chemical bonds are the most efficient way to store energy. For example, carbon-carbon bond or carbon-hydrogen bond would probably be the most practical energy storage in the near future. To store energy in liquid fuel, particularly biologically derived liquid fuel, the carbon-carbon bond formation ability provided by biological systems is probably the most unique aspect of biology’s contribution to this energy problem.

One concern brought up by a participant is the energy density in biological products is also low, and will limit some of the applications. Also there are energy losses at every step away from the initial harvesting of light or energy. That has to be taken into consideration when looking to biology for inspiration for energy solutions.

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