Energy - Royal Society of Chemistry
For this essay’s purposes, the most important ecological understanding is that the Sun provides all of earthly life’s energy, either (all except nuclear-powered electric lights driving photosynthesis in greenhouses, as that energy came from dead stars). Today’s hydrocarbon energy that powers our industrial world comes from captured sunlight. Exciting electrons with photon energy, then stripping off electrons and protons and using their electric potential to power biochemical reactions, is what makes Earth’s ecosystems possible. Too little energy, and reactions will not happen (such as ice ages, enzyme poisoning, the darkness of night, food shortages, and lack of key nutrients that support biological reactions), and too much (such as , ionizing radiation, temperatures too high for enzyme activity), and life is damaged or destroyed. The journey of life on Earth has primarily been about adapting to varying energy conditions and finding levels where life can survive. For the many hypotheses about those ancient events and what really happened, the answers are always primarily in energy terms, such as how it was obtained, how it was preserved, and how it was used. For life scientists, that is always the framework, and they devote themselves to discovering how the energy game was played.
Solar Energy News -- ScienceDaily
Although large amounts of solar energy are irradiated to the earth's surface, the effective energy concentration (energy/unit area) of solar energy at any one point on the earth's surface is small - only about 1 kW/m2 at most, even at noon.
Cyanobacteria and plants use photosynthesis to make their own fuel from nothing more than CO2, water, and the sun's rays. Artificial photosynthesis is therefore any process that attempts to mimic nature by chemically storing solar energy inside of a fuel. Artificial photosynthesis also includes any technologies that attempts to replicate any part of the photosynthetic process. The term is often used to describe a variety of technologies, including the photocatalytic splitting of water into hydrogen fuel and oxygen gas, the use of photosynthetic microorganisms for biofuels, or the complete biomimicry of the photosynthetic reaction process to create chemical fuels.
American Energy Independence and America's Solar Energy Potential
Conventional solar power, , which involves the direct conversion of photons into DC current via the photovoltaic effect, is mired by costly materials, intermittency issues, cloudy weather, and the need to store electricity in a battery. Photosynthesis in nature may just hold the answers to all of these problems. The advantage to creating a fuel is the ability to use existing piping infrastructure, and easily store energy for use when sunlight is unavailable. The protein complexes from photosynthesis could also be used to replace costly rare earth metals used in conventional solar cells, driving costs down.
Plant Energy Transformations-Photosynthesis
By achieving better than one-percent efficiency in “artificial photosynthesis” in the laboratory — a better efficiency than that of plants — scientists could produce significant amounts of clean, renewable energy, but the challenges to overcome are difficult. While plants use chlorophyll to absorb sunlight, scientists use a photo-electrochemical cell to absorb light and to separate charges. The separated charges initiate complex chemical reactions that store the solar energy as fuels such as hydrogen or methanol. Brookhaven chemists are working on finding stable, visible light absorbing materials for the cell’s anode.
What Is Photosynthesis? From Light Energy to Chemical Energy
Catalysts are needed in two separate reactions in artificial photosynthesis to produce solar fuel, such as molecular hydrogen from water. A crucial step in the process is water oxidation — one part of “water splitting,” or breaking water into hydrogen and oxygen. Water splitting requires a large amount of energy from sunlight and effective metal catalysts to activate the very stable water molecules. The process occurs as two separate “half-reactions.” In one, water oxidation produces molecular oxygen along with protons and electrons; in the other, these protons and electrons are combined to make molecular hydrogen.
Chapter 2 - Energy conversion by photosynthetic …
Most Americans, however, use solar energy in its secondhand form: . When sunlight strikes a plant, some of the energy is trapped through photosynthesis and is stored in chemical bonds as the plant grows. Of course we can recover that energy directly months or years later by burning plant products such as wood, which breaks the bonds and releases energy as heat and light. More often, though, we use the stored energy in the much more concentrated forms that result when organic matter, after millions of years of geological and chemical activity underground, turns into , , or . Either way, we’re reclaiming the power of sunlight.