My choices:

1. Ocean biomass ethanol. Location: 70% of Earth's surface.
2. Offshore wind. Location: Gulf of St. Lawrence.
3. Concentrated solar thermal. Location: Mexico.

That article surprised me. I knew that fractional distillation of petroleum always yields roughly the same relative amounts of diesel, gasoline, asphalt, lubricants, polymers, etc. But I didn't realize that led to inelastic supply economics. Very important. If an alternative like ocean biomass is to make a serious dent in fossil fuel consumption, it may have to supply similar fractions.

That's a tough one. Not to dispute the incredible achievement, but we keep building up this 'civilization' using non-renewable fuels. When we run out we're screwed. For example people who buy cars that can only burn gasoline: they can't just switch to a new fuel.... their answer to high gas prices is to simply park it. People can't afford to just buy a new vehicle if the fuel becomes too expensive.

Here is a list of vehicles currently made that run interchangeably on either gasoline or ethanol:

Current Model Year Flexible Fuel Vehicles

Funny thing is alot of people already drive these vehicles and aren't aware they could be using ethanol instead.

The reason biomass is so great is because oil originally came from biomass. Million-year-old biomass gives us a black tar-like substance called oil from which inferior fuels can be made. Freshly grown biomass gives us clean burning, zero-net-emissions, renewable ethanol which cleans your engine of combustion residues and makes your engine last 2-3 times longer.

Using the oceans to grow more salt-water-adapted biomass is a good idea since it won't compete with food crops for land, and 4% predation by microorganisms will serve the food chain and increase fish stocks, and just about every other type of marine life.

I'm working on it.