Photosynthesis is a biological process used by many cellular organisms to convert light energy into chemical energy, which is stored in organic compounds that can later be metabolized through cellular respiration to fuel the organism's activities. The term usually refers to oxygenic photosynthesis, where oxygen is produced as a byproduct and some of the chemical energy produced is stored in carbohydrate molecules such as sugars, starch, glycogen and cellulose, which are synthesized from endergonic reaction of carbon dioxide with water. Most plants, algae and cyanobacteria perform photosynthesis; such organisms are called photoautotrophs. Photosynthesis is largely responsible for producing and maintaining the oxygen content of the Earth's atmosphere, and supplies most of the biological energy necessary for complex life on Earth.
In botany, a stoma, also called a stomate, is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange. The pore is bordered by a pair of specialized parenchyma cells known as guard cells that regulate the size of the stomatal opening.
The green sulfur bacteria are a phylum, Chlorobiota, of obligately anaerobic photoautotrophic bacteria that metabolize sulfur.
Biological carbon fixation or сarbon assimilation is the process by which inorganic carbon is converted to organic compounds by living organisms. The compounds are then used to store energy and as structure for other biomolecules. Carbon is primarily fixed through photosynthesis, but some organisms use a process called chemosynthesis in the absence of sunlight.
Phototrophs are organisms that carry out photon capture to produce complex organic compounds and acquire energy. They use the energy from light to carry out various cellular metabolic processes. It is a common misconception that phototrophs are obligatorily photosynthetic. Many, but not all, phototrophs often photosynthesize: they anabolically convert carbon dioxide into organic material to be utilized structurally, functionally, or as a source for later catabolic processes. All phototrophs either use electron transport chains or direct proton pumping to establish an electrochemical gradient which is utilized by ATP synthase, to provide the molecular energy currency for the cell. Phototrophs can be either autotrophs or heterotrophs. If their electron and hydrogen donors are inorganic compounds they can be also called lithotrophs, and so, some photoautotrophs are also called photolithoautotrophs. Examples of phototroph organisms are Rhodobacter capsulatus, Chromatium, and Chlorobium.
Artificial photosynthesis is a chemical process that biomimics the natural process of photosynthesis to convert sunlight, water, and carbon dioxide into carbohydrates and oxygen. The term artificial photosynthesis is commonly used to refer to any scheme for capturing and storing the energy from sunlight in the chemical bonds of a fuel. Photocatalytic water splitting converts water into hydrogen and oxygen and is a major research topic of artificial photosynthesis. Light-driven carbon dioxide reduction is another process studied that replicates natural carbon fixation.
Water splitting is the chemical reaction in which water is broken down into oxygen and hydrogen:
The methanol economy is a suggested future economy in which methanol and dimethyl ether replace fossil fuels as a means of energy storage, ground transportation fuel, and raw material for synthetic hydrocarbons and their products. It offers an alternative to the proposed hydrogen economy or ethanol economy, although these concepts are not exclusive. Methanol can be produced from a variety of sources including fossil fuels as well as agricultural products and municipal waste, wood and varied biomass. It can also be made from chemical recycling of carbon dioxide.
The photosynthetic efficiency is the fraction of light energy converted into chemical energy during photosynthesis in green plants and algae. Photosynthesis can be described by the simplified chemical reaction
Microbial metabolism is the means by which a microbe obtains the energy and nutrients it needs to live and reproduce. Microbes use many different types of metabolic strategies and species can often be differentiated from each other based on metabolic characteristics. The specific metabolic properties of a microbe are the major factors in determining that microbe's ecological niche, and often allow for that microbe to be useful in industrial processes or responsible for biogeochemical cycles.
Hydrogen gas is produced by several industrial methods. Fossil fuels are the dominant source of hydrogen. As of 2020, the majority of hydrogen (~95%) is produced by steam reforming of natural gas and other light hydrocarbons, and partial oxidation of heavier hydrocarbons. Other methods of hydrogen production include biomass gasification and methane pyrolysis. Methane pyrolysis and water electrolysis can use any source of electricity including renewable energy.
Daniel George Nocera is an American chemist, currently the Patterson Rockwood Professor of Energy in the Department of Chemistry and Chemical Biology at Harvard University. He is a member of the National Academy of Sciences and the American Academy of Arts and Sciences. In 2006 he was described as a "major force in the field of inorganic photochemistry and photophysics". Time magazine included him in its 2009 list of the 100 most influential people.
Rhodopseudomonas palustris is a rod-shaped, Gram-negative purple nonsulfur bacterium, notable for its ability to switch between four different modes of metabolism.
An autotroph is an organism that produces complex organic compounds using carbon from simple substances such as carbon dioxide, generally using energy from light (photosynthesis) or inorganic chemical reactions (chemosynthesis). They convert an abiotic source of energy into energy stored in organic compounds, which can be used by other organisms. Autotrophs do not need a living source of carbon or energy and are the producers in a food chain, such as plants on land or algae in water. Autotrophs can reduce carbon dioxide to make organic compounds for biosynthesis and as stored chemical fuel. Most autotrophs use water as the reducing agent, but some can use other hydrogen compounds such as hydrogen sulfide.
Photosynthesis systems are electronic scientific instruments designed for non-destructive measurement of photosynthetic rates in the field. Photosynthesis systems are commonly used in agronomic and environmental research, as well as studies of the global carbon cycle.
A solar fuel is a synthetic chemical fuel produced from solar energy. Solar fuels can be produced through photochemical, photobiological, and electrochemical reactions.
Carbon-neutral fuel is fuel which produces no net-greenhouse gas emissions or carbon footprint. In practice, this usually means fuels that are made using carbon dioxide (CO2) as a feedstock. Proposed carbon-neutral fuels can broadly be grouped into synthetic fuels, which are made by chemically hydrogenating carbon dioxide, and biofuels, which are produced using natural CO2-consuming processes like photosynthesis.
The Hill reaction is the light-driven transfer of electrons from water to Hill reagents in a direction against the chemical potential gradient as part of photosynthesis. Robin Hill discovered the reaction in 1937. He demonstrated that the process by which plants produce oxygen is separate from the process that converts carbon dioxide to sugars.
Carbon capture and utilization (CCU) is the process of capturing carbon dioxide (CO2) from industrial processes and transporting it via pipelines to where one intends to use it in industrial processes.
Stafford W. Sheehan is an American scientist and entrepreneur, a co-founder and chief technology officer of Air Company. He developed a heterogeneous catalysis process to convert carbon dioxide into ethanol that his company has used to produce vodka and other consumer products as well as jet fuel.
