The Sahara Forest Project  

Posted by Big Gav in , , , , , , ,

I've posted plenty of stories about solar thermal power in the Sahara, a scheme long ago dubbed deserts of gold, with most of them talking about large scale CSP plants in North Africa supplying clean energy to Europe. The Guardian has a new twist on this vision, with desert CSP plants being twinned with "seawater greenhouses" that grow crops using desalinated water produced using waste heat from the power plant - Environment: Solar plant yields water and crops from the desert.

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.


hey dude.. very good blog.. informative and interesting.. keep up the good work.. nice to see your vivid and unique interest! :) my best wishes :)

Enjoying your blog.

I hope now is finally the time when technological capabilities, economic realities, and social awareness leads us to clean power sources such as solar. I have a question about the greening of the Sahara, however... It seems whenever we humans tinker with the environment, we get unintended consequences. Is greening the Sahara any less destabilizing than burning off the Amazon rain forest? I ask out of ignorance, not out of spite. Thanks, MooseGoose

Thanks guys.

MG - yes - if we actually succeeded in "ggreening" whole desert there would undoubtedly be unintended consequences.

However - it (and other deserts in the middle east and elsewhere) are vast, so I struggle to imagine these sorts of facilities would ever cover anything more than small percentage of the available land.

As they rely on seawater, they need to be fairly close to the coast for starters.

Comparing the two articles on Africa... this one and the microbial fuel cells... I think the MFC is much more likely to succeed. This one seems more of a "World Bank" style mega project more for the benefit of non Africans.

The MFC project uses simple easily disseminated technology with an immediate benefit to the people - recharging mobile phones thus maintaining communications.

Although many people seem to think that the "third world" will suffer most from oil depletion (maybe), I sometimes wonder if these nations will be the first to adopt usable "low tech" appropriately scaled technologies while "the West" turns up its collective nose because that won't power the plasma TV!

Thus driving the "myth" that "our society" can only run on prodigious amounts of power (read nuclear).

"I've posted plenty of stories about solar thermal power in the Sahara, a scheme long ago dubbed deserts of gold, with most of them talking about large scale CSP plants in North Africa supplying clean energy to Europe."

Don't the North Africans need clean energy? Or if they don't use much electricity now, surely after years of producing heaps they'll start using it?

I wonder if in future we'll end up with an Export Land Model for renewable energy...

It's very interesting to me because I am on the tourism industry. Thanks

Tim Auld   says 3:21 PM

No doubt CSP is a good alternative to traditional fossil fuel powered electricity generation, and growing food in a greenhouse is better than importing it from afar. What would encourage me more, however, is a realisation that these kinds of projects will not make places like Dubai sustainable. If we are not willing to make many small sacrifices that lead us to a simpler way of life then one thing or another will become scarce, overdrawn or over-polluted. It seems that doing those steps first would be prudent. We could then use the resources saved to build an appropriate amount of renewable capacity. Unfortunately the progress myth makes us believe we do not have to give up anything or change our ways.

dr huda   says 9:56 PM

great effort indeed......the whole idea is favouring humnaity.

great effort indeed......the whole idea of project is in favour of humanity

SP - my long held view is that it isn't an either/or choice - both solutions are good - its a question of what is appropriate - economically, environmentally, culturally etc - in each location.

MFCs are great in undeveloped, off-grid villages and remote areas. CSP plants (and other facilities hanging off them) are great in deserts.

Its not a matter of choosing one or the other.

kiashu - I'm not implying that the electricity gets sent offshore to Europe exclusively - with power generation the basic premise is that it is available on the local grid as a starting point, and the surplus is exported through one or more interconnectors.

Taking the ELM model into account is an interesting idea, but its worth referring to that map of north africa in my solar thermal post which shows how much area is required to satisfy global energy demand.

Given that there is far more energy available than we will ever need, and that it is completely renewable and appears again every day, it isn't really appropriate to apply a peak / depletion model and an ELM overlay.

If we need more power, then add more CSP plants...

Tim - can you explain why you think these sorts of facilities couldn't make cities in the deserts sustainable ?

Granted Dubai's current level of excess isn't sustainable, but why couldn't the city be transformed to one that relies on power and fresh water generated by the sun ?

Even more so for places like Masdar that are designed to be sustainable in the first place.

(I still believe in the myth of progress, I might add, in spite of the general lack of it that we see in many places)

This is a classic of mixed statistics. The article mentions that 20 hectares will cost 80 million euros and that if we had 1% of available desert we'd have 20% of the worlds energy covered. 1% of the worlds desert is the equivalent of 49 million hectares. So if 20 hecatares cost 80M euros then 49 million hectares will cost 196 TRILLION Euros.

All of these ideas are great but people need to be able to write credible business cases to get people to invest. Using spurious figures like "only 1% of the earths deserts" is not helpful.

Sorry, made a mistake, it's 64 Trillion Euros to cover 1% of the earths deserts.

mark spencer   says 8:05 PM

Why is it that any good ,long term green project is always torn apart as unrealistic and grossly overpriced.The nuclear industry,always grossly over budget,never very efficient,extremely dangerous,highly polluting and a very limited resource, there is not that much Uranium on Earth,is hardly a good sustainable sustitute. mark spencer.

mark spencer   says 8:19 PM

An important consideration about costs of such projects as csp, are that once started the costs of expansion come from the profits of the earlier set up, it's called reinvestment. C.S.P. is also very efficient at providing the energy required to smelt metals and glass from ores and so dramatically cut it's own costs and pollutants.Could you imagine how far the oil industry would have got if someone suggested setting up thousands of oil rigs all over the world and how much all that super structure would cost. (ignoring the profits for reinvestment !) The nuclear industry was set up wiyhout even knowing if it could be safely decommissioned, let alone how much it would cost!

You certainly won't see me suggesting the nuclear industry is a cheap or viable alternative.

A lot of green megaprojects are expensive - but so is pretty much every other megaproject.

Sean H   says 10:13 AM

This project could be a great way to create jobs and investment in the depression economy we're in. The European union, private investors, and possibly Obama could put up the billions of dollars needed. On that scale, enough jobs, electricity, and food would be created to turn around this economic downturn.
On another note I have noticed that green technology doesn't replace black (coal, oil) or orange (nuclear) energy. It just adds the amount of energy available. Green energy will only replace other forms when they either run out, cost too much, or get shut down by the government.

If all the world were a garden then we would have nothing to fight about. (hopefully)

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