Greening deserts

On this page:

  1. Desert + sea = FOOD!
  2. Sahara forest project
  3. What about the nutrients?
  4. The Seawater ‘Net-house’ is 10 times cheaper than the Greenhouse!
  5. Protein from deserts?
  6. Water efficient crops: ABC’s Landline says we should try hemp!
  7. This is NOT geoengineering. Ethical questions about ‘reforesting the Sahara’ (as if we could!)

1. Desert + sea = FOOD!

Seawater dripping down cardboard cools – primitive but cheap tech

They pipe seawater from the coast into a solar-powered greenhouse. Solar thermal technology desalinates the seawater into freshwater. They drip cool seawater down cardboard sheets to cool the greenhouse cheaply. The freshwater runs the hydroponics in this climate controlled greenhouse in the desert.

Sundrop are already doing this – and can convert desert within a few hundred kilometres of the ocean into a food bowl.

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


2. The Sahara Forest Project

3. 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.

Also, let’s not forget that any desert city on the ocean can also use that ocean to have 3d seaweed and shellfish farms to be food independent, even food exporters! They could also harvest abundant seaweed as fertiliser for their greenhouses and local soils. Local agriwastes can then be biocharred to give the soil and even greater boost.

4. 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

5. 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.

6. Water efficient crops: ABC’s Landline says we should try hemp!

  • 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

7. This is NOT geoengineering. Ethical questions about ‘reforesting the Sahara’ (as if we could!)

Geo-engineering ALL our vast deserts into forests might at first sound like a great idea, but it could be dangerous and will definitely cost too much in today’s economy.
Dangerous: What other effects would reforesting the entire Sahara and Australian outback have? What desert biology and ecosystems would we snuff out? Unique life forms should be protected at all cost. The biodiversity crisis is one of the great challenges we face this century, and simplistic application of super-sized geoengineering schemes could wipe out whole categories of species that have their own intrinsic value and might even have commercial value. Evolution and biodiversity and unique ecosystems are special things where nature has answered questions we don’t even know how to ask yet! We destroy them at our peril.
Cost: deserts into forests is ridiculously expensive. The idea sounds great — desalinate enough seawater and grow new forests to solve global warming. Who can be against solving global warming and more trees, right? But we’re talking about truly vast areas, the Sahara and Outback! It’s just too costly. $3.5 trillion dollars a year!

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!

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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