A partial list of people working on it:
* Amyris
* Solazyme
* KiOR
* Algenol
* Sapphire
* Aurora
* Synthetic Genomics
* Cellana
* PetroSun
Notably, most of the companies on that list have taken hundreds of millions of dollars from domestic and foreign oil companies hoping to create their own supply. Maybe more notably, several of the companies on the list went public, then lost 80-90% of their market cap. Most are pursuing other, higher value products as a first-order business, with promises of biofuels down the road.
Remember that the transition from wood to coal occurred largely because the world was running out of wood. Otherwise, wood had a lot to commend itself: it was locally available (coal comes from limited locations), doesn't involve mining dangers, and is easier to burn (some early coal proponents in the US were accused of fraud when the "rocks" they sold wouldn't burn in existing ovens -- anthracite coal is tough to ignite).
Where opportunistic feedstocks exist, I suspect biofuels may supply some energy, but it's going to be a very small fraction of existing fossil consumption in advanced nations.
There have been some interesting developments in biofuels lately with Algenol peaking above >10,000 gallons/acre/year rate and demonstrating a sustained rate north of 8,000 gallons/acre/year. There have been some murmurs of breakthroughs in genetically modifying the photosynthesis pathway as well, which could have a dramatic affect on per-acre productivity.
Is that algenol productivity associated with open-air production, or is that in an artificial controlled environment with UV lighting and a highly engineered grow space?
Even if those production rates can be sustained, you're looking at 30 million acres for algae cultivation.
Technical details are thin, but I've found their 9kgal/acre-yr release:
http://www.biofuelsdigest.com/bdigest/2013/03/11/algenol-hit...
If you manage to build some of the infrastructure in the oceans, the area doesn't even matter (that doesn't mean it would be easy, there is just lots of room).
A few hundred miles on a side is the size of many larger states in the US, and that assumes a 100% fill factor. Add in requirements for access roads, equipment, human habitations and support, and that's going to increase, though I'm not sure by how much -- 10% to 30% wouldn't surprise me.
Built as a corridor, 30 million acres is 1000 miles x 47 miles -- an assembly of grow tanks stretching 25 miles on either side of an highway running from Chicago to Denver. Though more likely it would be situated in a desert region (so as not to compete with existing agriculture), but where it would compete with alternative direct electrical (or electricity-to-fuel) alternatives.
Even if the area doesn't require freshwater access, it will require water, and for that to be transported (likelihood of occupying thousands of miles of coastline are slim) considerable distances inland, and then back out again (waste streams and salt). All of which are both capital and operationally intensive.
Building sea-based structures would similarly be insanely capital intensive. You'd be better off finding a way to create an inland salt lake (say: in the Dead Sea or Death Valley) and situate your grow-ponds there.
Marine or even simply salt-water environments are very, very harsh and hard on structures (even concrete) and equipment.
You can also put some of those acres in other places, you don't have to take them all from Texas.
You're constrained by alternative land uses, requirements for sunlight, avoiding freezing (even in Texas and California, desert regions see frosts), and access to seawater.
Elsewhere in the world you could situate grow ponds in warm desert regions: the Sahara, northern and western Australia, the Arabian peninsula (somewhat ironically, requires more comic san(d)s), and similar areas, though these would be among the largest.
The world uses 100 million barrels of petroleum daily, the US about 20 million (slightly less). Even small uses of petroleum such as aviation (about 2% of the total) represent vast amounts of fuel. And with projected population and energy utilization growth, demand will increase above this.
The basic maths are laid out in a paper I've found to be a tremendously useful reference, Jeffrey Dukes, "Burning Buried Sunshine": http://globalecology.stanford.edu/DGE/Dukes/Dukes_ClimChange...
Briefly: present human consumption of net primary productivity (plant growth) is about 14% of Earth's total. The fossil fuels consumed in 1997 (the date analyzed by the paper) comprise the equivalent of another 21% of NPP (and the actual period over which the fossil fuels accumulated is far greater: 400 years of growth, accumulated over ~5 million years, due to inefficiencies in the process of coal, oil, and gas formation and accumulation).
You can look at biofuels on an energy per unit area basis. There's roughly 1 KW/m^2 of incident sunlight. Current PV solar cells convert around 20% of this, and tend to capture the equivalent of 8 hours of sunlight per day, which is to say, a 30% capacity factor. Maximum PV efficiency (with far higher costs of production) is around 85%. But with present commercially available means, you can capture 20% of 1 kW for 8 hours each day, or roughly 1.6 kWh per day. A kilowatt (kW) is a unit of power, a kilowatt-hour is a unit of energy.
US electrical production of roughly 4,000 TWh would require 7800 km^2 of area to produce, or a square 88 km on a side.
That's for electricity.
Plants and algae have an efficiency of from 1-10%, with conventional crops and plants generally in the 1-3% range. We can do the same area calculation as above, or work from yields expressed as gallons of fuel per acre. A high-yield crop such as canola is generally given as 100 gal/acre, hemp advocates claim as much as 300 gal/acre (though this is generally disputed), and algae biofuels as much as 1000 gal/acre.
Given the 7.3 billion barrels of oil consumed, lets work out acreage requirements for algae. GNU Units is one of my favorite tools for this:
You have: 7.3 billion barrels / (1000 gallons/acre)
You want: million km^2
* 1.2407662
There are presently slightly more than 400 million acres of land under agricultural production in the US. Three quarters of that would have to go to fuel production under one of the most productive biofuel processes we have.
Moreover, algae require ponds, which is to say, a LOT of water, pumping pesticide, fertilizer, and a lot of processing.
Say you figured out a way to move all of this off-shore, and could set up grow-ponds in the oceans off the Atlantic and Pacific coasts? They're roughly 1000 miles long each, so to figure on the width of our algae grow structure, we divide 479,000 by 2000 and find ... the ponds would have to extend only 239 miles off-shore. That's from Key West, FL, to Eastport, ME, from San Diego, CA, to Port Angeles, WA. And they'd have to survive freezing and nor'easters and hurricanes and ...
Yeah, sounds kinda tough.
If the US population and per-capita energy utilization were far less, say maybe 10% of present levels, this might be conceivable, but as things stand, not really. And then there's the rest of the world.
Even more modest proposals to, say, supply aviation fuel from halophyte + aquaponics farms, described by Boeing as the biggest breakthrough in biofuels, really doesn't add up: http://redd.it/1wo2hl
(Another interesting fact I discovered in researching that was that the US hit Peak Aviation Fuel in 1999, and present flight activity is more than 30% below what projections of that time suggested. Passenger miles are up somewhat given increased load factors -- more bumped flights and less legroom due to cramming more people onto fewer flights. Kopits points this out also in his presentation, confirming my observations.)
Which is why I find the NRL's project so interesting. The magnitude of its plant and scale requirements is far, far less than competing biofuel alternatives.
Reading about that is probably one of only two positive things I've read about in the last decade. The other being birthrates dropping in the US and elsewhere.
What I particularly like about the US NRL research is (pardon if I'm repeating myself):
• It's based on two very well-established technologies: hydrogen electrolysis and the Fischer-Tropsch process. I suspect other power-to-gas processes are based on this or similar (Sabatier process,
• The novel techology is reasonably minor: CO2 extraction from seawater. Much of the research involves improving the efficacy of this process.
• It addresses the feedstock challenge: CO2 content of seawater is relatively large.
• It is a good match for sustainable energy sources, both base-load (geothermal) and intermittent / variable (solar, wind, tidal).
• It produces well-understood liquid hydrocarbons for which we have considerable experience in utilization.
• Costs and scale appear reasonable.
• It appears highly sustainable.
Dropping birthrates is indeed another positive, though that's got to move far further.