Lighting. It's not as sexy as electric cars, solar thermal plants or biofuels, But it's a key component of greentech. Kaj de Daas, chiarman of Philips Lighting North America, provided an overview of the lighting market at the Dow Jones Alternative Energy Innovations conference today and here's what he said.

• $75 billion: the overall size of the global lighting market. The U.S. accounts for 20 percent of the total. (Philips does about $3.5 billion a year.)

• 52: The average number of light sockets in a U.S. home. Put another way, there are 4 billion screw-in light sockets in this grand land of ours. Although the U.S. is the largest market, it's the slowest when it comes to adopting new technologies.

• 40: The average number of sockets in a home in the Netherlands.

• 5, now 18: The average number of sockets in the recent past (5) in a home in Shanghai compared to the present.

• 2012: The year, in some nations, that traditional incandescent bulbs will no longer be sold.

• 45 lumens per watt: That's the minimum level of efficiency he'd like to see mandated.

• 5 milligrams: The amount of mercury in a compact florescent.

• 3: The number of universities in Shanghai that have well-regarded departments in lighting. If you want to know why Philips is conducting more research there, that's the answer.

• $1 to $3.50: The average price of LED chips. It's too high, den Daas said. Technically, companies can make LED bulbs that can dim and put out as much light as a traditional bulb. Economically, it's just not feasible right now.

• The Whole Enchilada: LEDs can last 50,000 hours. Thus, light bulb makers will lose their replacement market when LEDs go mainstream. The solution? Philips is shifting to making entire lamps and light fixtures. "I need ot offer something big to offset replacements," he said.

• $17: The amount of kerosene bought by households in Ghana to fuel lamps. Philips has started to sell cheap LED lamps in that country to reduce the danger and fossil fuel consumption presented by these lights.

• November 5: The date that Philips will release a new line of LED lamps for the hotel industry.

Bug eat bug. That’s the business model of Blue Marble Energy.

The Seattle-based company has come up with a system for generating algal blooms in wastewater facilities and then feeding the algae to other microbes. These other microorganisms in turn metabolically convert the algae into high-value industrial chemicals like propyl butyrate, said CEO Kelly Ogilvie, speaking at the Dow Jones Alternative Energy Innovations conference taking place in Redwood City, Calif.

Why? That chemical sells for $801 a gallon, a heck of a lot more than $4 a gallon algae-based biodiesel, he noted. An algae biofuel company might get $500 worth of oils out of directly harvesting and processing algae. The indirect method proposed by Blue Marble can yield $4,000 worth of chemicals from a ton of algae. Harvesting a ton of the green goo costs about $190, he said.

And there are environmental benefits as well. Wastewater treatment isn’t cheap or easy. Municipalities spend huge amounts of money dumping chlorine into wastewater to clean it out. Wild algae can take out nitrogen and other compounds from the water as well as the chemical-based processes without the environmental degradation and fossil fuel consumption involved in producing and spreading industrial chemicals in the first place. Plus, unlike chemically treated wastewater, the process yields a feedstock (algae) that can be converted into a valuable product. Other plant matter can be fed into it.

“Algae is the preferred feedstock, but we are really a biomass play,� he said.

Optimism aside, there's a lot more to making money off algae that mixing up some sewage and letting nature take its course. There are over 50 algae companies, but only a few (GreenFuel Technologies, Solazyme, Sapphire, LiveFuels) have cracked many of the elements required to turn slime into something valuable.

Ogilvie admitted in fact that the ultimate output of chemicals from its process can vary, depending on the algae that was used. Variability can be the kiss of death in the chemistry industry.

The heart of the operation is a system called AGATE, or acid, gas and ammonia targeted extraction. It is a combination digester and fermenter. Digesters are used by other companies to decompose manure and turn it into methane. The fermenter is the part that converts the algae into an enhanced chemical byproduct.

The company has a modest prototype that can process 1/10^th of a ton of biomass. Blue Marble is currently putting together a larger prototype in Brittany, France. It is now raising money for a 5,000 ton commercial-scale system.

Blue Marble has patents on much of its intellectual property, but this is also the sort of system that could be produced by large manufacturers like Siemens.

Microorganisms are going to be named the greentech employees of the century, mark my words. They can work in filth, don’t take breaks and you can squeeze out their entrails without risking a lawsuit. You can’t even do that with temps anymore. Sure, we might all contract a futuristic, incurable case of dysentery from a microbe experiment gone awry, but think of the cost savings.

Another company mining microbes for industrial chemicals is Genomatica, funded by Draper Fisher Jurvetson.

It’s a large mesh sack for raising tuna.

Hawaii Oceanic Technology has devised an aluminum and Kevlar sphere, measuring 162 feet in diameter, in which it hopes to raise sashimi-grade tuna three miles off the coast of Hawaii. The spheres sit 60 feet below the surface.

The company wants to plant these spheres in a 250-acre plot of ocean it has leased off of the coast of the islands. (Hawaii has an ocean leasing program.) A plot this size could generate 6,000 tons of tuna a year, which translates to $120 million dollars in gross revenue. (A single sphere could generate $20 million in revenue.) Plus, it’s a lot easier and more energy efficient for fishermen to extract tuna from what is essentially a large holding pen than fish for them miles out to sea. A single sphere holds 82,000 cubic meters of water.

Demand is not a problem.

“Our [global] aquaculture needs will double in the next 20 years,� said CEO Bill Spencer, at the Dow Jones Alternative Energy Innovations conference taking place this week. “The U.S. already imports 85 percent of its seafood, and half of that amount comes from Asia.�

Japan alone, he added, consumes 630,000 tons of sashimi-grade ahi a year.

Instead, skepticism persists about farm-raised ocean swimmers like tuna and potential environmental hazards. Scientists have experimented with farming tuna in Panama for around 12 years. It seems to work, he said. While the environmental impact needs to be studied, the environment for the fish is similar to the ocean. The Kevlar mesh lets water pass, so the water is continually cleaned and oxygenated.

Power for running the communication devices and some pumps at the spheres can be supplied by outboard motors, but the company is looking at trying to provide energy with a Stirling engine. Stirlings harvest power from the collision of hot and cold masses. In Hawaii Oceanic’s case, the power would come from putting warm surface water into one end of a tube and cold deep water in the other.