Energy & Green Tech

Sustainable biodiesel from neem tree trans-esterification

The neem tree, Azadirachta indica, also known as the Indian Lilac, is well known for its oil extracted from its seed and fruit. It has been used in traditional medicine but has also been investigated for the pest control ...

Energy & Green Tech

Engineers go microbial to store energy, sequester carbon dioxide

By borrowing nature's blueprints for photosynthesis, Cornell University bioengineers have found a way to efficiently absorb and store large-scale, low-cost renewable energy from the sun—while sequestering atmospheric carbon ...

Energy & Green Tech

Benefits of renewable energy vary from place to place

A new study from North Carolina State University finds that the environmental benefits of renewable power generation vary significantly, depending on the nature of the conventional power generation that the renewable energy ...

Energy & Green Tech

Porsche launches effort to make carbon-neutral 'e-gas'

Porsche has no plan to make an electric version of its iconic 911 sports cars. So, how to ensure continued sale of its flagship model far into the future, when governments around the world, including California's, are planning ...

Electronics & Semiconductors

New semiconductor coating may pave way for future green fuels

Hydrogen gas and methanol for fuel cells, or as raw materials for the chemicals industry, for example, could be produced more sustainably using sunlight, a new Uppsala University study shows. In this study, researchers have ...

Energy & Green Tech

Ambitious but controversial: Japan's new hydrogen project

Japan's new 2050 deadline for carbon neutrality has thrown a spotlight on its efforts to find new, greener fuel options, including an ambitious but controversial liquid hydrogen venture.

Energy & Green Tech

A blast of gas for better solar cells

Treating silicon with carbon dioxide gas in plasma processing brings simplicity and control to a key step for making solar cells.

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Carbon dioxide

Carbon dioxide (chemical formula: CO2) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state.

Carbon dioxide is used by plants during photosynthesis to make sugars, which may either be consumed in respiration or used as the raw material to produce other organic compounds needed for plant growth and development. It is produced during respiration by plants, and by all animals, fungi and microorganisms that depend either directly or indirectly on plants for food. It is thus a major component of the carbon cycle. Carbon dioxide is generated as a by-product of the combustion of fossil fuels or the burning of vegetable matter, among other chemical processes. Large amounts of carbon dioxide are emitted from volcanoes and other geothermal processes such as hot springs and geysers and by the dissolution of carbonates in crustal rocks.

As of March 2009[update], carbon dioxide in the Earth's atmosphere is at a concentration of 387 ppm by volume. Atmospheric concentrations of carbon dioxide fluctuate slightly with the change of the seasons, driven primarily by seasonal plant growth in the Northern Hemisphere. Concentrations of carbon dioxide fall during the northern spring and summer as plants consume the gas, and rise during the northern autumn and winter as plants go dormant, die and decay. Carbon dioxide is a greenhouse gas as it transmits visible light but absorbs strongly in the infrared and near-infrared.

Carbon dioxide has no liquid state at pressures below 5.1 atmospheres. At 1 atmosphere (near mean sea level pressure), the gas deposits directly to a solid at temperatures below −78 °C and the solid sublimes directly to a gas above −78 °C. In its solid state, carbon dioxide is commonly called dry ice.

CO2 is an acidic oxide: an aqueous solution turns litmus from blue to pink. It is the anhydride of carbonic acid, an acid which is unstable and is known to exist only in aqueous solution.

CO2 is toxic in higher concentrations: 1% (10,000 ppm) will make some people feel drowsy. Concentrations of 7% to 10% cause dizziness, headache, visual and hearing dysfunction, and unconsciousness within a few minutes to an hour.

This text uses material from Wikipedia, licensed under CC BY-SA