... to the environment as other large scale agricultural projects.
It would be similar to shrimp farming, non-organic rice cultivation, and so on.
To reduce non-productive competitive species of bacteria and algae a lot of antibiotics and other chemicals would probably have to be added to the water. Imagine how herbicide resistant crops are cultivated, and you'll get a good idea of how oil-producing algae would be cultivated.
Did you mean DME, not BME?
DME,
Di-Methyl-Ether, is handled almost exactly like propane. It is not corrosive and not as toxic as methanol. A liquid gallon of DME carries about 85% the energy of a gallon of commercial propane-butane "bottled gas."
1.7 gallons of DME is the energy equivalent of a gallon of gasoline, although in practice a DME fueled diesel engine would probably be more efficient than a gasoline engine, which brings that number down somewhat.
Here's a quick chart of gasoline energy equivalents by volume--
Fuels that can be used with existing technologies:
gasoline 1
propane 1.5
ethanol 1.6
DME 1.7
methanol 2.4
cng 3.0 (compressed natural gas)
Fuels that would require use of advanced technologies:
lng 1.3 (liquified natural gas)
wood pellets 2.1
liquid hydrogen 3.7
compressed hydrogen 10.1
Diesel engines get better milage than gasoline engines. DME would be used in diesel engines.
In practice, the use of bio-diesel reduces milage by 2-7%
Hydrogen, either compressed or liquid, in comparison to other fuels, does not fare well. Liquid hydrogen and compressed hydrogen are difficult to handle and would require the use of exotic high-efficiency technologies such as fuel cells to be practical.
I put wood pellets in this chart because a few months ago we were talking about wood-pellet fueled tractors and railroad locomotives in this forum.