Venus' runaway greenhouse effect a warning for Earth

Venus was transformed from a haven for water to a fiery hell by an runaway greenhouse effect, concludes the European Space Agency (ESA), after studying data from the Venus Express, which has been orbiting Venus since April 2006.

Venus today is a hellish place with surface temperatures of over 400°C (752°Fahrenheit), winds blowing at speeds of over 100 m/s (224 mph) and pressure a hundred times that on Earth, a pressure equivalent, on Earth, to being one km (0.62 miles) under the sea. 

Hakan Svedhem, ESA scientist and lead author of one of eight studies published on Wednesday in the British journal Nature, says that Earth and Venus have nearly the same mass, size and density, and have about the same amount of carbon dioxide (CO2). In the past, Venus was much more Earth-like and was partially covered with water, like oceans, the ESA scientists believe. 

How could a world so similar to Earth have turned into such a noxious and inhospitable place? The answer is planetary warming. At some point, atmospheric carbon triggered a runaway warming on Venus that boiled away the oceans. As water vapour is a greenhouse gas, this further trapped solar heat, causing the planet to heat up even more. So, more surface water evaporated, and eventually dissipated into space. It was a "positive feedback" -- a vicious circle of self-reinforcing warming which slowly dessicated the planet. 

"Eventually the oceans began to boil," said David Grinspoon, a Venus Express interdisciplinary scientist from the Denver Museum of Nature and Science, Colorado, USA. "You wound up with what we call a runaway greenhouse effect," Hakan Svedhem says. Venus Express found hydrogen and oxygen ions escaping in a two to one ratio, meaning that water vapour in the atmosphere — the little that is left of what they believe were once oceans — is still disappearing. 

While most of Earth's carbon store remained locked up in the soil, rocks and oceans, on Venus it went into the atmosphere, resulting in Venus' atmosphere now consisting of about 95% carbon dioxide. 

“Earth is moving along the curve that connects it to Venus,” warns Dmitry Titov, science coordinator of the Venus Express mission. 

References: 

Venus Express - European Space Agency (ESA) 

http://www.esa.int/SPECIALS/Venus_Express/SEMGK373R8F_0.html 

Venus inferno due to 'runaway greenhouse effect', say scientists 

http://www.physorg.com/news115477239.html 

Probe likens young Venus to Earth 

http://physicsworld.com/cws/article/news/32018 

European mission reports from Venus 

http://www.nature.com/nature/journal/v437/n7062/full/4371071a.html

Combat Global Warming with Evaporative Cooling

Combat Global Warming with Evaporative Cooling - by Sam Carana

To combat global warming, wind turbines along the coastline could be used for the dual purposes of generating electricity at times when there is wind and evaporating water at times when there is no wind. Just a small breeze over the water can give the top water molecules enough kinetic energy to overcome their mutual attraction, resulting in evaporation of water and associated cooling of both water and air.

Such dual use of wind turbines can be implemented at many places where turbines overlook water; evaporation will work most effectively in hot and dry areas, such as where deserts or dry areas meet the sea or lakes. Evaporative cooling will add humidity to the air, which can also cause some extra rain and thus increase fertility of such dry areas as a beneficial side effect.

The energy needed to run the turbines can be obtained and stored in a number of clean, safe and renewable ways. ]

At times when there is plenty of wind, surplus energy from the turbines could be used to convert Water into hydrogen by means of electrolysis. Alternatively, bio-waste could be burned by means of pyrolysis to create both hydrogen and agrichar, which could be used to enrich soils. The hydrogen could be kept stored either in either compressed or liquid form, ready to power fuel cells that can drive the turbines at any time, day or night.

Another alternative is to run the turbines on electricity from concentrated solar thermal power plants in the desert. A desert area of 254 km² would theoretically suffice to meet the entire 2004 global demand for electricity. Ausra offers a solar thermal technology that uses the sun's heat to generate steam, which can then be stored for up to 20 hours, thus providing electricity on demand, day and night. Ausra points out that just 92 square miles of solar thermal power facilities could provide enough electricity to satisfy all current US demand.

Finally, there are some environmental concerns about wind turbines. There are concerns about carbon dioxide being released into the atmosphere in the process of making the concrete for the turbines. To overcome this, turbines could be made using alternative manufacturing processes, which can be carbon-negative. Furthermore, a recently completed Danish study using infrared monitoring found that seabirds steer clear of offshore wind turbines and are remarkably adept at avoiding the rotors.

In conclusion, wind turbines have a tremendous potential. They can potentially generate 72 TW, or over fifteen times the world's current energy use and 40 times the world's current electricity use. Offshore and near-shore turbines can make seawater evaporate and thus cool the planet, at times when they are not used to generate electricity.

References:

Ausra
http://ausra.com/

Wind power - Wikipedia 

http://en.wikipedia.org/wiki/Wind_power

Evaluation of global wind power 

http://www.stanford.edu/group/efmh/winds/global_winds.html

Solar power and electric cars, a winning combination! 

http://www.gather.com/viewArticle.jsp?articleId=281474977115548

Agrichar 

http://www.gather.com/viewArticle.jsp?articleId=281474977139103

Alternative method of manufacturing concrete 

http://www.tececo.com/

Massive Offshore Wind Turbines Safe for Birds 

http://www.technologyreview.com/Energy/18167/


Footnote: This article was written by Sam Carana; it can be freely copied and published elsewhere, as long as the autor's name is retained in the article.

Polar ejection of carbon dioxide

Dr. Alfred Wong of the University of California, Los Angeles, proposes to send carbon dioxide into outer space using lasers and radio waves at the arctic.

See A stairway to heaven? in The Economist

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