Solar plant yields water and crops.
Posted by: kaizenlog in Kaizenlog, tags: Solar plant yields water and crops.I believe we can do something similar in Malta as well.
http://www.guardian.co.uk/environment/2008/sep/03/alternativeenergy.renewableenergy
Environment: Solar plant yields water and crops from the desert
���· Green energy glasshouses may transform arid areas
���· Fresh water will end need to dig wells, say architects
Alok Jha, green technology correspondent
Wednesday September 3 2008
The Guardian
Vast greenhouses that use sea water for crop cultivation could be
combined with solar power plants to provide food, fresh water and
clean energy in deserts, under an ambitious proposal from a team of
architects and engineers.
The Sahara Forest Project, which is already running demonstration
plants in Tenerife, Oman and the United Arab Emirates, envisages
huge greenhouses with concentrated solar power (CSP), a technology
that uses mirrors to focus the sun’s rays, creating steam to drive
turbines to generate electricity.
The installations would turn deserts into lush patches of
vegetation, according to its designers, and do away with the need to
dig wells for fresh water, an activity that has depleted aquifers
across the world.
Charlie Paton, a member of the team, and the inventor of the
Seawater Greenhouse, said the scheme was a proven way to transform
arid environments. “Plants need light for growth but they don’t like
heat beyond a certain point,” he said.
Above certain temperatures the amount of water lost through leaves’
stomata rises so much plants stop their photosynthesis and do not
grow. The solar farm planned by the project runs seawater
evaporators, pumping damp, cool air through the greenhouses. This
reduces the warmth inside by about 15C, compared with the
temperature outside.
At the other end of the greenhouse from the evaporators, water
vapour is condensed. Some of this fresh water is used to water the
crops, some for cleaning the solar mirrors.
“So we’ve got conditions in the greenhouse of high humidity and
lower temperature,” said Paton. “The crops sitting in this slightly
steamy, humid condition can grow fantastically well.”
The designers said that virtually any vegetables could be grown in
the greenhouses. The demonstration plants already produce lettuces,
peppers, cucumbers and tomatoes. The nutrients to grow the plants
could come from local seaweed or be extracted from the seawater.
Michael Pawlyn, of Exploration Architecture, based in London, worked
on the Eden Project for seven years and is now part of the Sahara
Forest team. He said that the Seawater Greenhouse and CSP provided
substantial synergies for each other. “Both technologies work
extremely well in hot, dry, desert locations. CSP produces a lot of
waste heat and we’d be able to use that to evaporate more seawater
from the greenhouse. And CSP needs a supply of clean, de-mineralised
water in order for the [electricity generating] turbines to function
and to keep the mirrors at peak output. It just so happens the
Seawater Greenhouse produces large quantities of this.”
Paton said the greenhouse produced more than five times the fresh
water needed to water the plants inside, so some of the water could
be released to the outside, creating a microclimate for hardier
plants such as jatropha, a crop that can be turned into biofuel.
The cost of the Sahara Forest Project could be relatively low as
both CSP and Seawater Greenhouses are proven technologies. The
designers estimate that building 20 hectares (nearly 50 acres) of
greenhouses combined with a 10MW CSP scheme would cost about
���� 80m (���£65m).
Paton said groups in countries across the Middle East, including in
UAE, Oman, Bahrain, Qatar and Kuwait, have expressed interest in
possibly funding demonstration projects.
He said use of Seawater Greenhouses could reverse the environmental
damage done by the glasshouses already built in places such as the
desert region of Almeria, southern Spain, where, constructed over
the past 20 years to grow salad crops, they now covered more than
40,000 hectares.
Paton said: “They take water out of the ground something like five
times faster than it comes in, so the water table drops and becomes
more saline. The whole of Spain is being sucked dry. If one were to
convert them all to the Seawater Greenhouse concept it would turn an
unsustainable solution into a more sustainable one.”
Pawlyn said: “In places like Oman they’ve effectively sterilised
large areas of land by using groundwater that’s become increasingly
saline. The beauty of the Sahara Forest scheme is that you can
reverse that process and turn barren land into biologically
productive land.”
Neil Crumpton, an energy specialist at Friends of the Earth, said
the potential of these desert technologies was huge. “Concentrated
solar power mirror arrays covering just 1% of the Earth’s deserts
could supply a fifth of all current global energy consumption. And 1
million tonnes of sea water could be evaporated every day from just
20,000ha of greenhouses.”
Governments should invest in the technologies and “not be distracted
by lobbyists promoting dangerous nuclear power or nuclear-powered
desalination schemes”, Crumpton added.
The International Energy Agency estimates that the world needs to
invest more than $45 trillion (���£22.5 trillion) in new energy
systems over the next 30 years.
Copyright Guardian Newspapers Limited 2008
If you have any questions about this email, please contact the
guardian.co.uk user help desk: userhelp [Email address: userhelp #AT# guardian.co.uk - replace #AT# with @ ].
Welcome back to Kaizenlog.com, you may want to subscribe to my RSS feed , Twitter You can contact us by using the contact form or submitting a comment. You can also share this post with your friends by clicking on the 'ShareThis' button above. Thanks for visiting!
Print This Post
Entries (RSS)