I landed at the Ft. Lauderdale airport yesterday and there was a sign that said that to decrease water use, the airport has changed its thermostat from 74 to 78. Call me hopelessly brown, but it seems to me that they can attract more money to pay for more water via tourism if their airport is comfortable rather than politically correct. Water can be recycled, pulled out of the ocean and the air. The economic value of the savings is summarized by the market price for more water which is still measured in hundreds of dollars per acre foot. An acre foot is enough water to cover an acre one foot deep, or 325,851, gallons putting the price of water in gallons per cent. Skimping on use is pain for no gain. Or is masochism the main point of being Green?

Food prices are up as corn prices have doubled to $4.50/bushel with the $0.51/gallon of ethanol subsidy. As the US is (soon to be was) a huge corn exporter, this is causing higher prices worldwide. Foreign Affairs in the May/June issue says that could lead to doubling the world hungry from 600 million to 1.2 billion. They hope that

relying more on sugar cane to produce ethanol in tropical countries would be more efficient than using corn and would not involve using a staple crop.

No, if sugar cane is more profitable than corn, it will also outcompete staples for land and labor until the price of staples is hungry high.

Scientific American makes the same mistake in the June issue:

[Jatropha, an oil crop] favors hot, dry conditions and hence an unlikely threat to rain forests. There is no trade-off between food and fuel either, because the oil is poisonous.

No, Jatropha will pull away farm equipment, labor and land from other crops driving up the price of every other crop.

Ethanol is an OK energy delivery system to convert solar energy, but if biofuels stay competitive with petroleum (via subsidies for now), all arable land will be converted to corn and other energy crops until the food crop prices are driven up enough to be competitive with the energy crops.

The only way to bring the corn price down is to either bring a multiple of the current acreage under cultivation (all US arable land devoted to corn would get us 12% of petroleum consumption) or reducing the corn/ethanol subsidy.

Taylor Dinerman calls for space solar power in this week’s The Space Review. He trots out hydrogen as an alternative energy source. No–it’s an alternative energy delivery method. Last time I checked, to get hydrogen, we had to use another fuel source and lose energy to crack the hydrogen. To make space solar power viable, we need an advance that will advantage space solar power to terrestrial solar power. Does this meet the objective:

One technology that might radically reduce the weight requirements for these systems is the technique pioneered at the University of Notre Dame where single-walled carbon nanotubes are added to a film made of titanium-dioxide nanoparticles, doubling the efficiency of converting ultraviolet light into electrons. Any solar cell technology that could reach conversion factors of over 50% or even higher would reduce the size and weight of an SPS and thus make it easier and cheaper to build and launch.

It also makes terrestrial solar power potentially reach conversion factors of over 50% too. To make space solar better than terrestrial solar, we need launch costs to be no more than 3x manufacturing costs per kg if space solar is 4x as efficient. With manufacturing costs $350/kg, we need launch costs $1000/kg to make space solar viable.