At the Cleantech Forum this week, startups seeking funding did their best song and dance. Here are some highlights.

Proterro: Bugs Take Over the Supply Chain

Proterro has identified a strain of cyanobacteria that naturally produces sugar, and the company has manipulated the DNA to improve yields. But what sets the company apart from the many genome startups in this space (think Genomatica, Amyris, Qteros) is that Proterro is enabling biochemical and biofuel startups, not competing with them.

The New Jersey-based company, which has raised $5 million from Battelle and Braemar, is seeking an additional $5 million to move into the engineering phase for its fermentation-ready sugar feedstock, dubbed Protose, which requires sunlight, water and CO2.

Proterro says it offers customers a feedstock for biofuels and biochemicals at a lower cost than corn, sugarcane and cellulose because it doesn’t require cultivation, harvesting, transportation or processing. CEO Kef Kasdin, also a partner at Battelle, says Protose is 30 times more productive per acre than corn and sugarcane and can be produced on non-arable land. Kasdin said it also requires less water than sugarcane, but declined to give specifics.

The 1-square-meter panel is modular, and Protose can be produced on-site with ethanol plants. Proterro plans to reach the market through partners, and is now sampling its sugar with potential downstream partners.

Porous Power: Separators to Improve Battery Safety, Performance

Porous Power Technologies has developed a membrane technology that it says can reduce the overall cost of lithium-ion cells by 20 percent, improve the speed of charging by 50 percent, and increase the length of life cycles by 20 percent to 25 percent.

The Colorado-based company’s spray-on separator technology is designed for large-scale applications of Li-ions, including electric vehicles, which require large, flat cells with stacked electrodes (see photo). The separators, dubbed Symmetrix, allow for a flow of materials that results in less heat and increased safety, the company says. We ran into them a little over a year ago at a conference in Tokyo. One big benefit to the idea: separators are more of a passive rather than active technology in a battery. Thus, there is a higher likelihood, in some minds, that large battery makers will adopt it.

Porous Power also plans to license its processes for stacked-cell production to battery manufacturers, promising a reduction in assembly times by a factor of 20.

The company has raised $3.2 million from angel investors, and is seeking a $5 million Series A for further product development, commercialization, and increasing sales in Asia.

The company recorded $750,000 in revenue in the past 12 months, and has a $12 million annual production and shipping capacity.

OPX Biotechnologies: Microbes Evolving Rapidly

OPX Biotechnologies uses genetically engineered microbes to produce biochemicals and biofuels, starting with bio-acrylic. The company hopes to attract customers looking for sustainable -- and less expensive -- solutions.

OPX says it has made significant progress in the past 18 months using the proceeds of its $18 million Series B round from investors Mohr Davidow, Braemar, Altira and X/Seed. The cost per pound to produce bio-acrylic dropped from $17.82 in July 2009 to $0.70 in the fourth quarter of 2010 -- with the eventual goal of reaching $0.50 per pound, said CEO Chas Eggert.

The Colorado-based company is seeking $35 million to fund its demonstration plant with an unnamed strategic partner, with full commercialization slated for 2014.

Power Tagging: Who Needs Cellular?

Power Tagging has developed hardware and software to track the flow of energy on the grid—a solution that could be deployed to utilities without the need for additional cellular, fiberoptic, wireless or radio frequency communications technology.

CEO John LoPorto says this gives the Colorado-based company a significant cost and reliability advantage when compares to traditional smart grid plays. The technology can be used for demand reduction, grid mapping, grid security, outage notification, distributed automation, and voltage regulation.

“We can use the most ubiquitous network in the world, which is the power grid,” he said, pitching to investors to raise a $20 million to $25 million Series B round to fund additional pilots and demonstration projects.

Power Tagging is undergoing demonstration projects across 19 miles of grid with four utilities, including Xcel Energy and Morgan County Rural Electric Association. Virginia-based power company Dominion, which is piloting the technology, has also invested in Power Tagging, which previously raised $5 million in a Series A financing. Lockheed Martin has also vetted the company’s technology.

LoPorto says the company’s technology doesn’t replace the smart meter—but it does replace the data communication module in today’s advanced meters. The technology uses algorithms to monitor energy flow on the grid in real time. LoPorto said the technology is imbedded so far down it avoids the typical interference by transformers and capacitors in communications.

The capex for utilities is essentially the same as wireless communications—about $300 a pop—but the utility saves on operating expenses, since there’s no recurring monthly fee for each meter, LoPorto said.

Gravity Power: Vertical Shafts Make for Cheap Storage

Gravity Power has developed a utility-scale energystoragedevice that’s cheaper and simpler than traditional pumped hydro, compressed air, or combustion turbine plants. The system hydraulically lifts a piston into a deep underground shaft to store energy, then releases the piston to force water through a hydro turbine to deploy energy. Boasting 75 percent to 80 percent efficiency, Gravity expects to offer this technology for less than $200 per kilowatt-hour of installed capacity. Eric Wesoff has written some stories on the company lately. EscoVale out of England has something similar: a 100-million-ton stone.

The initial market for this technology is ancillary services such as frequency regulation, which require smaller (and cheaper) systems than most grid-level applications, CEO Jim Fiske said in an interview. The company is also pursuing peak-energy plants, which currently account for 12 percent of grid capacity in the United States. The third potential market is intermediate plants, which can run 10 to 12 hours a day.

The California-based company has raised $3 million from the Quercus Trust and 21Ventures, and is seeking $4 million, which is expected to help Gravity Power complete its prototype this year. The company expects to complete a commercial demonstration by 2013. Advantages of the technology are the small footprint of the system, quick ramp-up, the ability to use existing shafts in South Africa and elsewhere, and the potential to store variable power sources such as wind and solar.