Energy & Green Tech

Carbon-neutral fuels from air and green power

Several challenges associated with the energy transition can be managed by coupling the sectors of electric power and mobility. Green power could be stored in the long term, fuels of high energy density could be used in a ...

Engineering

Clearing up the 'dark side' of artificial leaves

While artificial leaves hold promise as a way to take carbon dioxide—a potent greenhouse gas—out of the atmosphere, there is a "dark side to artificial leaves that has gone overlooked for more than a decade," according ...

Energy & Green Tech

Leaner, cleaner diesel engines

Diesel engines are widely used in transport the world over. Regulatory and legal efforts are afoot to reduce their use in some countries because of concerns about pollution. However, they are likely to remain a mainstay of ...

Energy & Green Tech

Solar energy becomes biofuel without solar cells

Soon we will be able to replace fossil fuels with a carbon-neutral product created from solar energy, carbon dioxide and water. Researchers at Uppsala University have successfully produced microorganisms that can efficiently ...

Energy & Green Tech

UK reaches jolly good milestone in days without coal

The UK has gone more than five days without burning coal, the longest streak without burning the fuel since the Industrial Revolution, said Bloomberg. It breaks the previous record from earlier this year, a total of 90 hours.

Energy & Green Tech

Eighteen countries showing the way to carbon zero

Eighteen countries from developed economies have had declining carbon dioxide emissions from fossil fuels for at least a decade. While every nation is unique, they share some common themes that can show Australia, and the ...

Engineering

Making cement sustainable

Cement production accounts for up to nine percent of global anthropogenic carbon dioxide emissions, according to the World Business Council for Sustainable Development. Sabbie Miller, assistant professor in the Department ...

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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