A La Jolla, Calif.-based company trying to address environmental problems by engineering cellular "bio-factories" topped the cleantech heap on the 2008 GoingGreen 100 Top Private Companies list.

Media company AlwaysOn presented its second annual list of game-changing private ventures in several cleantech sectors, such as biofuels, energy efficiency and nanotech. Synthetic Genomics was named the overall winner while solar ventures dominated the list of companies that, as a group, are beginning to move beyond beta testing to product development.

The winners will be honored Sept. 15-17 at GoingGreen in Sausalito, Calif., a conference dubbed a cleantech "love fest" by AlwaysOn Editor Tony Perkins.

"It really focuses in on where the venture capital opportunities are in greentech," Perkins said of the conference. "It also brings together a lot of the larger players like British Petroleum, Best Buy and others who are particularly interested in learning how to update their operations, new technological items ... and also look to invest in -- and sometime acquire -- some of these companies."

Since September 2007, more than $1.6 billion has been poured into the companies comprising the inaugural GoingGreen 100.

Founded in 2005, overall winner Synthetic Genomics specializes in taking a micobrial approach to advanced biofuel design, subsurface hydrocarbon recovery and production, and plant feedstocks. "I think that company is really on fire," Perkins said.

A company is crowned in each category, including:

Amyris Biotechnologies -- Biofuels
CoalTek -- Clean energy
GlycosBio -- Clean manufacturing and clean products
Silver Spring Networks -- Energy efficiency and energy management            
Premium Power -- Energy storage systems
EcoMotors -- Green automobiles and transportation
Serious Materials -- Green materials, green buildings
Genomatica -- Green nanotech and synthetic genomics
Za-Gen -- Resource recovery and waste management
Bright Source Energy -- Solar energy
AbTech Industries -- Water technology and water management