Desert Farming Experiment Yields Good Initial Results

Taco Cowboy writes "For the past year or so, a tiny scale farming experiment in has been carried out in the desert field of Qatar, using only sunlight and seawater. From the article: 'A pilot plant built by the Sahara Forest Project (SFP) produced 75 kilograms of vegetables per square meter in three crops annually (or 25 kilograms per square meter, per crop)' If the yield level can be maintained, a farm of the size of 60 hectares would be enough to supply the nation of Qatar with all the cucumbers, tomatoes, peppers, and egglants that it needs. 'The project will proceed to the next stage with an expansion to 20 hectares, to test its viability into commercial operation.'"

Comments

Economics

[captainpanic]

I am very curious about the economics of this type of farming. (Note, I am not necessarily a skeptic). The cost of the water is obviously a driver to make sure the maximum amount of water is recycled. I wonder if they use hydroponics?

Greenhouses are used at large scale elsewhere with a lot of success. The Netherlands has a large area of greenhouses to produce tomatoes and peppers (and a lot more). There, the water is not a bottleneck, but sunlight is. So, lamps are used. I guess that is just as costly, showing that the economics of a greenhouse are not necessarily a problem.

Re:Economics

[thegarbz]

The arab countries never really worried about energy efficiency in the past. The problem there is every drop of drinking water is effectively sourced from desalination. The town water in Qatar tastes absolutely crap and even the hotels typically provide 2L bottled water bottles in the rooms (can't wait to hear the complains from the upcoming world cup).

This creates a very interesting problem for farming in the desert which looks absolutely fascinating on Google Maps

Check out the green irrigation circles dotted all over the place.

Compared to that this is almost more of a traditional farming method.

Re:Economics

[Anonymous Coward]

Fact. Supposition. One guy's theory. Supposition.

The BBC just ran a piece on how population growth is slowing, global inequality has been reduced from a stark binary proposition to a continuum, and rates of global literacy are skyrocketing, just for a bit of contrast there.

I've been toying with Solar desal for awhile.

[upuv]

It's really good to see some one follow through on this. This is excellent.

I've been toying and drawing up plans for very low maintenance solar desal for years. All the same basic components as this. But they have taken a few steps further than I was thinking. I had not worked in humid air as a means of watering plants. It really solves a lot of issues with condensing the water.

Problems like biomass build ups and the effort to clean it. Now that effort is productive as it is harvesting food not just cleaning sludge off the walls.

I really like it.

I had wind to pump salt and fresh water up hill. So that I would have a reserve of each at all times. That way wind could be used to build kinetic energy and store it as raise water mass. Salt water of course to feed the evaporators and to flush waste back out to sea. Fresh for obvious uses.

Something I have struggled with is a solar tracker that would allow a mirror to stayed focused on a water pipe to heat it to near steam to accelerate the evaporation. Something that does not actually require elctro-mechanical input.

Re:I've been toying with Solar desal for awhile.

[upuv]

I have considered the trough. But there is so much lost solar radiation this way if you don't have some tracking in place.

Basically I get more solar heat transfer if I just have a glass cover over a shallow pond that is painted black. I just don't get the temperature high enough to create a more efficient evaporation. It's just ends up being slower at a lower temp. Which then results in more biomass growth. I'd like to have close to boiling to hinder algae and such in the solar collector system.

So I'm stuck with a lot of labour with either method. However the construction costs are much lower with the black pond method.

I have been tossing around some ideas on how to automatically adjust the angle using struts that expand and contract with heat. Just need to find the right balance of expansion and contraction I hope to cause the system to angle itself as the sun passes overhead. My current thinking is something like a shock absorber filled with gas. A gas shock could cause contraction or expansion of a joint when cooled. So somehow tying the heated sea water into the system to control it's own angle.

Re:I've been toying with Solar desal for awhile.

[Coppit]

I had some kids in a class I was teaching invent an umbrella that used a closed system of two connected canisters, one on each end. The liquid inside (I forget which) was chosen so that when heated it became *more* dense, causing the sun-ward side to be heavier, turning the umbrella toward the sun. It seems that sort of passive system is possible, if you wanted to go down the invention road. :)

That yield seems very high.

[Anonymous Coward]

I work in agricultural research (cropping) and I'm a bit curious about those yields. Working on a single crop, that's 250 ton/hectare. For most crops in heavy clay soils the best you can hope to achieve is 8 - 12 (maybe 15 if you're *really* lucky). Now again, that's for crops, not vegetables, but I find it hard to believe that vegetables could yield over 20 times as much. Is this right? Is the weight mostly water? Are they able to grow year round with all the heat? I still find it hard to believe as even if you could get 5 harvests a year (and I'd be surprised if they got more than 3) that's still 50t/ha/harvest.

Re:fertilizer?

[biodata]

There isn't a worry here about salination of the soil because the salts end up in the evaporation columns. I saw a lo-tech version of this described a couple of years ago at the UK Plant Sci conference, and this project sounds like an outgrowth from that - they also described the effect on the land outside the greenhouse, with spontaneous growth of native desert flora due to the increased external humidity. The experimenters used a greenhouse with a cardboard wall on the upwind side - the sea water soaks up the wall and is evaporated into the greenhouse by the wind, leaving the salts in the cardboard. After a few years the cardboard wall is a very rigid mineral-rich material that you can use for building structures like sheds.

Re:Why those vegetables?

[taiwanjohn]

Although I fully support and applaud this effort, this is not the only way to get the job done. Permaculture design can achieve similar results with much smaller inputs, as described in this video.

The most important concept of permaculture is water management. If you only get 8" of rain per year and it all comes within a 3-week window, you'd better have your land "sculpted" to optimize retention of water on the surface for as long as possible. Such improvements last for generations, and continually add fertility and biodiversity to the land.

If we seriously applied these principles worldwide, we could make the entire globe flood-proof and drought-proof in less than a decade. Seriously.

For example, check the before & after photos in Green Gold or in this TED Talk by Allan Savory. These amazing transformations happen in just a few years. Imagine what would be possible over the long term.