Greening deserts

On this page:

  1. It’s about small projects to meet local needs
  2. Grand, but not grandiose – not reforesting the Sahara!
  3. Seawater greenhouses: sea + desert = food!
  4. Sahara forest project — lots of Seawater Greenhouses
  5. What about the nutrients?
  6. The Seawater ‘Net-house’ is 10 times cheaper than the Greenhouse!
  7. Protein from deserts?
  8. Water efficient crops: ABC’s Landline says we need hemp!
  9. Other desal methods? The Max Whisson Water Highway.
  10. Not Geoengineering! – the case against reforesting the whole Sahara

1. It’s about small projects to meet local needs

This page is about greening even old natural deserts that have not known regular rainfall for tens of thousands of years – but doing so on a local basis in the desert, especially if they have local access to the ocean. Also, remember that if they have access to the ocean they should also be getting a majority of their protein and fertiliser and even fibre needs from Seaweed and Shellfish farms in coastal waters.

2. Grand, but not grandiose – not reforesting the Sahara!

The local desert greenhouses here are about greening smaller local areas to supply the local village or town or even city with some or all of their needs. But we’re not trying to reforest continent-sized deserts like the African Sahara or Australian Outback. This is about local ‘greening’ to meet local needs, not geoengineering to save the world. As Tim Flannery says, seaweed grows 30 times faster than trees and can be grown vastly cheaper and faster than reforestation schemes to save us from climate change. See point 10. Geoengineering notes below.

Also, reforestation is about reversing the damage we have done, not creating something artificial that requires artificial maintenance. Poor agricultural techniques have expanded deserts across the globe. Let’s reverse that and use the best science to restore these areas to their former glory — not artificial and expensive new glory.  It should return to a natural balance with local rainfall or moisture in the area, and not require artificial intervention to keep going. See my reforest page for more.

3. Seawater greenhouses: 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

4. The Sahara Forest Project

5. What about the nutrients?

Desert city near ocean = Seaweed and Shellfish farms in coastal ocean waters that could already feed them. Then extra seaweed can more than fertilise their land. But wait, there’s more! 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

6. 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

7. 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.

8. Water efficient crops: ABC’s Landline says we need 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

9. 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.

10. Not Geoengineering! – the case against reforesting the whole Sahara

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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