I recall that if you do not chlorinate pools and hot tubs in Arizona, they will soon become filled with yellow-green algae. Am not sure if you could keep a pure algae strain in a pond as other species might quickly infiltrate and compete against higher lipid algae.

In some Florida offshore areas nitrogen from onshore was entering shallow water via rivers and streams. This caused algae bloom. The algae shaded out the sea grass that was the habitat of shrimp and numerous species of fish. It also depleted oxygen from the water. The growth rate of algae might be limited by nutrients and available oxygen.

These early algae models were not very efficient in their predictions of labor, energy, harvesting & processing costs, plant and equipment prices, land rent or mortgage costs, other borrowing costs, taxes etc.

With subsidies the California solar industry is growing quickly. One may need to compare the amount of energy provided per dollar between all types of renewable energies including wind, solar, hydroelectric, tidal, geothermal, and biomass. Some wind and hydroelectric projects were advancing without subsidies. A few geothermal projects were profitable without subsidies. Solar preheating of water before it entered water heater tanks has proved to be economical in areas not too far north.

With ethanol there has been some success in Brazil, yet it is causing the loss of forest habitat and creating greenhouse gas that was not properly considered by those promoting ethanol. In the United States it was calculated that to meet govt. ethanol standards forty percent of the grain (corn + wheat) might be required. Such a rapid increase in acreage of corn planted is not happening in 2008. Other nations' biofuels programs might also lead to grain deficits and spiking food prices. Grain prices tripled since 2005 when ethanol use became mandatory.

Food price increases cannot all be attributed to rising energy costs, else the price of homes, cars, clothes, electricity, etc. might have tripled.