Does "unused" land mean land which is currently covered in rainforest? If so, clearing it for palm oil production has obvious ecological drawbacks.

While I happen to think that liquid biofuels can contribute significantly towards our short- and medium-term efforts to reduce our petroleum consumption, I also think that we need to be very mindful of the ecological consequences of increased farming activity. The increased energy consumption that goes alone with increased farming activity is only part of that story, and the other elements must not be ignored.

Planting farms for biodiesel is silly when algae has a much higher yield. Any excess food produced can be used but it makes little sense to not chose the most efficient feedstock for the primary source.

As for water, they are situated in a wet/dry monsoon climate.
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___The problem I see is how to forestall a) the further destruction of the rain forests b) contamination of algae production by algae consuming fish/microorganisms.

Intensive algae farming to save rainforest acreage would be laudable, but it does require a source of CO2 to enrich the pools. The original NREL study suggested using scrubbed flue gases from coal-fired power stations, with some 90% dissolving in the water.

Note that carbonating water will make it more acidic. The NREL research involved bioprospecting for species that deliver the desired lipids (in that case, the objective was biodiesel) but can also tolerate highly acidic pH conditions. Those would pretty much put paid to Allen's concern about little fishies coming to eat the algae.

Robert: that how we prepare a land in M'sia, not too sure about Thailand. We use machine can do dozens times more job then men and dozens times faster with one man operating the machine. Lets say we need RM20 for an indon worker(cheap labour) per day and 1 week to clear 1 acres, a bulldozer can deal with 10 acres in one day.

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Algae farming? Come on guys, even the most developed country here not doing this in industrial scale and stick to soy bean oil and rape seed oil. Be realistic, dont always say something that is not exsist is better.

Algae farming is only good for producing health suppliment. And we have plenty of it. Try convince them to turn to oil production?

Unused land in Southern Thailand is that which has already been denuded for rubber plantations. 60,000 rai is but a speck on the map of millions of rai under rubber trees.

As for algae farms, I dread to think of the destruction that will be caused when this is allowed to run riot like the current spate of fish-farms around Thailand's coasts. There is constant pollution and debilitation of natural fish and shellfish stocks, especially where control is over-ridden by corruption.

'Algae being cheap' is probably the last thing Thailand needs just now.

I've lost my link to the NASA system which calculates the annual insolation for points on the map, but that never stopped me from scribbling on envelopes.

A typical PV system may have 16% electric efficiency and cost upwards of $5 per peak watt.  Figuring 900 W/m^2 of sun, that's somewhere over $720/m^2 of collector area.

Suppose that the hypothetical algae system is $7/m^2.  So what if it's only 3% efficient?  It would still collect almost 20 times as much energy per dollar as the PV.  Instead of needing a fraction of a typical house's roof area to meet its needs, it might need the whole thing plus the garage and maybe a bit of the yard.  At $7/m^2, you could cover the whole roof for a thousand bucks.

The roof of a 140 m^2 ranch house in S. California might capture close to 30 kWh over the course of a day, even at 3%; that's most or all of what the house needs.  Relatively small "energy farms" would certainly do the job of powering civilization as we know it.

This environmentalist says, "Bring it on."