Biofuels: solar energy transfer station

At the first CS3 conference, Dr. James Barber of the Imperial College in London described plants as "macro-reaction vessels" that were driven by photosynthesis for 2.5 billion years. Plants in nature convert solar energy into biomass energy and can be further transformed into biofuels for easy use by people. But scientists have suggested that if biofuels are to be widely promoted, they must develop chemical methods that can create more biomass, and catalytic processes that improve the efficiency of biomass conversion.
Opening the Regional Application Space According to the white paper “Use Sunshine to Drive the World”, biomass is not the fundamental solution to the global energy challenge. As Barb explained, the application of biomass is limited by two factors. First, the photosynthetic efficiency in the natural world is not high. Most plants can convert up to 4.5% of the solar energy absorbed into carbohydrate fuels. They need to improve their efficiency through technologies such as genetic or biochemical engineering. Second, the conversion of solar energy to biomass energy. The speed is not high, and large-scale cultivation of fuel biomass requires a lot of land. He believes that it is unrealistic to expect that by 2050 the use of one third of the earth's land for planting biofuel biomass will be unrealistic.
Despite this, CS3 participants emphasized that biofuels can be used as local or regional energy solutions. For example, Brazil has successfully converted sugar cane into fuel ethanol in the past few decades, thereby satisfying about one-third of the energy supply. U.S. biofuels meet 3% of energy demand, and there is huge room for development. At present, the global fuel ethanol production still maintains its growth momentum.
Scientists believe that while the argument that biofuels can largely meet the world's energy needs is somewhat exaggerated, it does not obliterate the unique role of biofuels. Dr. Mark Davies of the National Renewable Energy Laboratory in Colorado, United States, said that photovoltaic cells, one of the solar technologies, have advantages in power production, but there is little possibility of producing liquid fuels. Dr. Ferdy Schutt of the Carbon Institute of the German Mapuistic Society mentioned that the future energy system will still be based on materials, and biomass is the most readily available material-based fuel.
Improve competitiveness from the whole process How to optimize the production of biofuels so that the scale of production can compete with fossil fuels? Barb believes that the most important thing is to make fuel biomass not compete with food crops, change the production of biofuels from food-based to fiber-based, and develop "energy cereals" for non-food plants and corresponding agricultural production technologies. . For example, many chemists are studying the use of a highly productive forage Miscanthus as a biofuel source.
The white paper points out that chemists also need to develop more suitable catalysts to convert hard-to-degrade cellulose into simply structured sugars and further convert them into fuel products. It is gratifying that some chemists' research results are close to solving this problem. They examined the natural enzymes secreted by termites and tested whether these enzymes could be used in energy conversion systems.
Davis agrees that a good catalyst can reduce the amount of energy needed to break and build chemical bonds. Experts believe that to reduce the cost of biofuels, different types of biomass feedstock should be used, better harvesting techniques should be developed, and certain chemical process steps should be changed so that biofuels can be more competitive with petrochemical fuels.
Focus on Life Cycle Research Davies' view on reducing the cost of biofuel production has led to a discussion of the whole life cycle study from biomass production to biofuel conversion. Scientists raised a series of questions: How much energy is needed to produce biofuels? Which reaction step has the largest energy loss? What aspects can be effectively improved? In fact, even in Brazil, where fuel ethanol has been widely used for decades, its full life cycle remains unclear.
CS3 participants believe that not only biofuels need to consider the entire life cycle, all solar energy technologies also need to consider the entire life cycle of the energy conversion process. For example, for artificial light synthesis technology, it is important not only to consider the energy output, but also to consider the energy needed to build the device and perform it. However, Davies stressed that the analysis and assessment of the life cycle and system level of solar energy conversion technology need to be very careful, because the results depend on the factors considered and the assumptions of the analysis.
According to Dr. Walter Ratner of the German Institute for Technology and Macromolecular Chemistry in Aachen, biomass can be used not only as a fuel source, but also as a raw material for high value-added downstream products. In fact, biomass can produce products that no other material can produce, such as lubricants and high electrolyte oils in the pharmaceutical industry. He appealed that "third generation" biomass conversion pathways should be considered. These include the research being conducted by the Institute to convert biomass into products with high added value, such as fuels, as well as chemicals, lubricants, drugs, and products that cannot be produced using other technologies.