Greening deserts

On this page:

  1. What’s the difference between this and reforestation?
  2. Seawater greenhouses make sea + desert = food!
  3. Sahara forest project video
  4. What about the nutrients?
  5. The Seawater ‘net-house’ is 10 times cheaper!
  6. Protein from deserts?
  7. Water efficient crops: ABC’s Landline says Australia needs Hemp food!
  8. Geoengineering: can desal green the Sahara & Outback? At what price?
  9. Who pays to desal the Sahara and Outback?
  10. Other desal methods? The Max Whisson Water Highway.

1. What’s the difference between this and reforestation?

Reforestation is about reversing the damage we have done to grasslands and forests that sees deserts marching across the globe. (See the page). Reforestation focuses on trying to restore what was originally there before we chopped it down. It should be in natural balance with local rainfall or moisture in the area, and not require artificial intervention to keep going.  But this page is about greening even old natural deserts that have not known regular rainfall for tens of thousands of years.

2. Seawater greenhouses make sea + desert = food!

As I understand it, this seawater greenhouse is about trying to economically grow food in deserts where there is a low population. In other words, this desert scenario is not like Israel’s where large populations in small areas make treating sewage economical for agriculture.

Sundrop are already doing this!

  • Sundrop technology can convert any desert within a few hundred kilometres of the ocean into a food bowl.
  • They pipe seawater inland into a solar-powered glasshouse
  • Solar thermal technology desalinates the seawater into freshwater
  • This freshwater irrigates hydroponic fruit and vegetables growing in the climate controlled glasshouse
  • Dripping cool seawater down cardboard sheets cools the greenhouse cheaply
  • The ABC’s Catalyst (below) demonstrates seawater greenhouse fruit and veg
  • The Guardian (Nov 2012) reports that they are making money, and coupled with algae technology, could grow fish and chicken.
  • “Academic agriculturalists, mainstream politicians and green activists are falling over each other to champion Sundrop. And the company’s scientists, entrepreneurs and investors are about to start building an £8m, 20-acre greenhouse – 40 times bigger than the current one – which will produce 2.8m kg of tomatoes and 1.2m kg of peppers a year for supermarkets now clamouring for an exclusive contract.”
  • Surplus salty brine can grow algae ponds outside for fish and chicken stock
  • The image below:
    1. Concentrated Solar Power;
    2. Saltwater greenhouses;
    3. Outside vegetation and evaporative hedges;
    4. Photovoltaic Solar Power;
    5. Salt production;
    6. Halophytes;
    7. Algae production


3. The Sahara Forest Project

4. What about the nutrients?

As Next Big future reports:

  • seawater  has many nutrients that can grow algae
  • algae can feed fish (see below) and chicken
  • excess water can grow hedges and eventually trees to shade outside crops in the desert
  • salty brine is then dried to sell salt
  • it’s about maximising profit, about both economic and ecological viability.
  • trees outside the greenhouses will create their own leaves and compost and build soil
  • trees companion plant other food producing trees and shrubs
  • with careful use of extra water and by using permaculture principles, we really can ‘Green the Desert’
  • towns can provide recycled sewage nutrients back onto farmlands. See Israel shows us the way.

Agriwastes like rice husks and straw can be processed through biochar to increase soil nutrients. With biochar and permaculture schemes, we can grow soil many times faster than nature can. Imagine them combined with the following more traditional permaculture system in this “Greening the desert” video: a classic 5 minute piece on growing food in deserts with a tiny trickle of drip irrigation

5. The Seawater ‘net-house’ is 10 times cheaper!

Business Green reports that simply replacing the glasshouse with netting for a much cheaper building: 10 times cheaper!

After three years of work, the company had designed a version of their system that was modular, and ten times cheaper than before. It still uses desalination and evaporative cooling, but it has nets rather than a traditional greenhouse. It was completed in October last year, and this week they harvested their first crop.

At the moment the 1 hectare farm sits in the middle of a barren patch of drylands. As it grows and develops, the fresh water being created by the solar desalination plant will begin to improve conditions beyond the greenhouse itself, creating an ‘oasis effect’. There are plans to grow beans, melons and other crops outside, and eventually re-green the area

6. Protein from deserts?

Anywhere large biomass is being grown and processed will have some waste. We can turn that into biochar to help the soil, but also dump a ton of biomass per day into a 4m by 4m insect farm that will convert it into protein for chickens, or with the right bug choice, protein for us directly! These desert oasis towns can grow their own protein, and the cities they feed can even turn restaurant scraps into more insect protein. It’s about whats the most economical and environmentally efficient way to feed the planet.

7. Water efficient crops: ABC’s Landline says Australia needs Hemp food!

  • Use some of that excess water to plant out a hemp-field outside the greenhouse
  • Hemp is an ideal desert crop an only uses a third the water it takes to grow lucen
  • Hempcrete soaks up CO2 as it dries and petrifies
  • Aboriginals are building hemp housing
  • Was the world’s most common fabric material until the cotton gin was invented.
  • Decorticator machine should fix hemp compared to cotton as it separates fibre from the bark more efficiently
  • More fibre per hectare, and better fibre than cotton!
  • Hemp oil & foods extremely nutritious: ice cream, bread, spaghetti, salad dressing, Omega oils like fish oils, even soap
  • Hemp is low THC (doesn’t get you high like it’s naughty cousin)
  • Economics fantastic!
  • Watch landline: 15 minutes below

8. Geoengineering: going huge and drying to irrigate the entire Sahara and Outback!

The projects above have been about local food production in the desert that is fastidiously managed and attached to the global food industry. But the approach below is probably more about government funded mass geo-engineering desalination to grow enough trees to store the world’s carbon. It’s huge, and expensive, and I’m not sure how many times over it would swamp the world’s need for building timbers and other longer term forest products. And at what cost? Tim Flannery’s Kelp mass kelp-farming dream seems more realistic, as at least that huge industry would produce synthetic oil! (See point 6 here: Kelp farming could fix climate change!)

Geo-engineering the Desert is quite depressingly expensive. The idea sounds great! We could, theoretically, desalinate enough seawater and grow enough forests to solve global warming. But we’re talking about desalinating so much water that we convert most of the Sahara and Outback into forest. And what other effects would that have? How much desert would we need to conserve for the various desert life forms that would otherwise lose their habitat and probably die out? What about the vast amounts of dust that blow off the Sahara and fertilise the oceans? What would the effect on our oceans be? Are there other ways to solve these problems?

Imagine the Sahara and Outback and Gobi deserts all green, growing vast forestry and fruit and medical products. Would all the associated growth industries eventually pay back the carbon-tax it took to desalinate that much water? There would be so much timber and food and fuel and fibre that the industries springing from them would be vast.

Now the price tag. This is just an intellectual exercise about sequestering ALL our CO2. I’m not suggesting we should: but that we should prevent that CO2 being released in the first place. Based on the paper below, I see it as costing $3.5 trillion dollars a year to fix global warming by sequestering all human CO2 emissions! (See Footnote 1 below). But if we put that money into nuclear power and recharging our cars, we’d prevent warming, and could then put a smaller government subsidy into reforestation schemes in areas kinder to trees that would gradually bring down global CO2 levels. Global GDP is $70 trillion. $3.5 trillion is a significant percent of global GDP dedicated to ‘mopping up’ carbon emissions.

9. Who pays to desal the Sahara and Outback?

Considering that the global agricultural output is worth 6.2% of world GDP, or $4.2 trillion a year, and this can only grow as our world’s population grows and demands more food, fuel, and fibre, we can see a potentially huge marketplace for desert grown food (and forests for fibre and fuel). Not only this, but sadly many of our best farmlands are deteriorating under poor management, and I’m all for bringing them back and storing more carbon in their soils. (See Replenish the soil). But this may not be enough! An extra 2 billion people will want food to eat, timber to build and fibre to clothe themselves. This is going to have to come from new farmlands, but there aren’t any! We’ve used all the good arable land, and the rest are mostly vulnerable ecosystems we should protect. So what’s the answer?

10. Other desal methods? The Max Whisson Water Highway.


A quick aside, another desal concept I’d love to see properly analysed is the  ‘Water Highway’ by Max Whisson. As far as I know this has not been commercially evaluated and might be far cheaper than the traditional means quoted elsewhere.

Dr Max Whisson, an inventor from Perth, Western Australia, believes that he has discovered a way to produce 200,000 litres of fresh water a day in a dry land. Max’s idea is to build a 1,000 km long 10 metre wide water producing freeway running a long distance inland from the sea then returning back to the sea again.

Max explained on the ABC’s Australian Story that the ocean contained an endless supply of fresh water that could easily be extracted by using thermal solar energy. Max’s scheme is to run a number of large parallel black pipes carrying sea water along this large scale water producing freeway. The 10 metre wide series of pipes would be covered by a transparent perspex cover. Daytime solar heat will cause the water in the pipes to heat up and 70% to 80% of the fresh water will evaporate off in a series of hot ponds in the circuit. Max Whisson said that hot air from the pond surfaces will be ducted up to condensation sheds where cooler atmospheric air causes distillation of the fresh water. At the end of the water road, the salty brine is returned to the sea or it could be used to produce sea salt, Dr Whisson said.

Max Whisson Water Road is a plan for abundant cheap desalination from pumping vast quantities of salt water along vast black pipes. Solar heat and carefully managed evaporative containers do the rest of the work. I would love to see the CSIRO or some corporation take this on board and at least build one at scale to see how economically this could produce vast quantities of water.  The cheaper the water, the more that can be done.

But who knows? If Sundrop and friends really have cracked a formula for food, fibre, and a little biofuel from our deserts and seawater, maybe one day the economic incentive will be so great, and the corporations involved so wealthy, that the penny will drop on some totally new method of desalinating seawater. Or they’ll try Max’s Water Road idea.


Footnote 1

My price tag for the desalinated water comes from page 416 of the PDF below.
It would cost $43 per ‘barrel’ of Carbon. A ‘barrel’ is 0.11 Ton C (Carbon, or 110kg Carbon). Humans emit 9 billion tons C a year.
9 billion / barrels (0.11 Tons C) = 81.818,181,818 ‘barrels’ of Carbon a year.
At $43 / barrel, that’s $3.5 trillion a year!
But as an energy source, this biomass could somewhat offset the price by selling liquid fuels, as long as the source regions are not depleted of their NPK nutrients. The forests should be biochar regenerated for maximal carbon sequestration and soil health, which all helps the longer term sustainability of the bio-oil industry.


4 Responses to Greening deserts

  1. Forrest is growing so are you sure you need 3,5 trillion every year or is this a one time investment , with possible profits after .

  2. Eclipse Now says:

    Trees in deserts need a continual supply of water to grow, and the cost is desalinating the water.

  3. singletonengineer says:

    They also need N,P and K or they don’t thrive. Where’s that coming from?.

  4. Eclipse Now says:

    Generally, the rocks and ground in the desert. We’re not growing *crops* here, but forests, so regular fertiliser isn’t required. Seawater greenhouses might order in some fertilisers, but they also get some of their nutrients form the seawater. But forests? If we’re talking about biocharing some of the produce from an earlier forest growth, and spreading that around, that’s a lot of NPK right there given the way the microbes can suck nitrogen out of the air and fix it in the soil as they die and reproduce. Soil life breaks down rocky ground and extracts nutrients. Insects return, birds hunt them and bring in nutrients in their droppings, animals return, and whole ecosystems come back to life. All with a little reliable water from us. This will be a gradual thing, and the new project can probably be boosted along from the previous one through biochar and various composting exercises.
    Watch this one to see how one project took *fairly* arid conditions, added water, and concentrated the *little* leaves and twigs in the area to form compost for the trees they were planting. Once that area came back to life, they could hypothetically spread out from there with minimal fertiliser input.

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