Getting off foreign oil may be very important for The USA and some other countries. Oil from algae looks promising (algae + water + carbon dioxide + sunlight yields up to 50% oil) but I think the following engineering problems are delaying large scale implimentation: Getting enough sunlight to the algae, requires thin layer and large surface area. The sunlight makes the algae too hot. The flue gas makes the algae too hot. The algae may get too cold at night. If you add the hot flue gas only from midnight to 10 am, how do you dispose of, or store, or cool, the flue gas 10 am to midnight ? Worse less flue gas is likely available midnight to 7 am and the flue gas arrives cooler as it is moving though the pipe slower and the ambient temperature is lower. The
above heat and light problems are worse in June, July, December and January = possibly you need to shut down the facility for these 4 months each year.
The water needs nutrients added = fertilizer. The water builds up chemicals from the flue gas that are toxic to the algae. The toxic water needs to be purified, before it can be dumped in a nearby dry stream bed/ the fertilizer needs to be replaced = probably cannot be economically separated from the toxins. Gas turbine exhaust is likely cooler and has less toxins than coal fired flue gas. Gas turbines are rarely operated midnight to 7 am. The percent of carbon dioxide is about half in gas turbine exhaust compared to coal flue gas, but enough water vapor is likely added to the algae to produce a surplus of water, between times when toxic water disposal is necessary. For a large facility, we may need to store millions of gallons of water for the next water replacement. Water is scarce, in locations with the most sunlight, such as New Mexico. Coal flue gas has about half as much water vapor and we don't need as much as it has double or more the carbon dioxide. Details like these, likely make the final products too costly to compete on the open market. Algae in transparent pipes helps the water loss problem, and contamination by less efficent algae. Two companies have functioning pilot plants Verde and Emerald, but neither are releasing details. Please refute, embelish and/or add details. Neil