Energy & Green Tech

Electric bikes and silent trucks to green goods deliveries

Across Europe's cities, the demand for delivery services is increasing. But these deliveries affect urban life as they add to traffic congestion, noise and pollution and many cities are now trying out alternative modes of ...

Energy & Green Tech

The paints that eat pollutants and heat homes

Applying a coat of paint on the walls of a house may soon help to heat it, saving energy and reducing CO2 emissions. It could also clean the air that we breathe, breaking down chemicals and pollutants, and eliminating harmful ...

Energy & Green Tech

Reducing power plants' thirst

Electricity production is one of the industries that uses the most water in the country each day. Researchers at Sandia National Laboratories are helping the largest power plant in the United States identify the most efficient ...

Energy & Green Tech

Co-combustion of wood and oil-shale reduces carbon emissions

Utilization of fossil fuels, which represents an increasing environmental risk, can be made more environmentally friendly by adding wood—as concluded based on the preliminary results of the year-long study carried out by ...

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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