But to a growing community of scientists and investors in Southern California, there is oil locked in all that slimy stuff, and several dozen companies are racing to try to figure how best to unleash it and produce an affordable biofuel.
The companies and several research labs have set up shop in the San Diego area, many of them in an area nicknamed Biotech Beach. There, about 200 biotech companies of all kinds are clustered near La Jolla on the mesa above Torrey Pines State Beach.
Together, the firms and organizations conducting algae research employ nearly 300 people with more than $16 million in payroll and bring $33 million annually into the local economy, according to the San Diego Assn. of Governments, and local officials see the potential for much more.
"It's a critical industry, and it's kind of exploded," San Diego Mayor Jerry Sanders said. "There's a long pattern of huge companies being spawned out of [UC San Diego] and our other research centers, and it's going to create a tremendous number of jobs."
National energy companies are converging on the fledgling industry. Exxon Mobil Corp. announced a $600-million partnership with La Jolla biotech company Synthetic Genomics Inc. in July. San Diego companies General Atomics and Science Applications International Corp. have received nearly $50 million from the Defense Department for algae fuel research.
Last year, $176 million was invested by venture capitalists to develop biofuel from algae, according to industry publication Biofuels Digest in Miami.
With the region's proximity to the ocean and its history with biotech businesses, San Diego is a familiar spot for clean-energy investors, Biofuels Digest editor Jim Lane said.
"It has all the magic conditions for the emergence of business life," he said. "San Diego wants to be associated with algae, while other cities have other fish to fry and think of algae as just one of many things."
Supplementing the research is experimental aquaculture, as farming in fresh- and saltwater is known. The arid Imperial Valley to the east is now home to several massive algae farms, one with nearly 400 acres of ponds in all shades of green being swirled by paddles to expose the organisms to more sunlight.
All of this activity has drawn its share of doubters.
Skeptics say that it's a beachcomber's fantasy, that it's too costly to cultivate any significant amount of algae, that fuel inside -- whether in the form of oil, ethanol, gas or hydrogen -- is too expensive to extract or produce on a large scale.
But in recent years, San Diego, along with Silicon Valley, St. Louis, Seattle and a few other cities, have disregarded the skeptics and emerged as hotbeds of algae biofuel research.
One of the nascent industry's major annual events, the 2009 Algae Biomass Summit, is headed to San Diego next month. It is put on by the Algal Biomass Organization, a Preston, Minn., group that seeks to promote commercial uses of algae products.
Seeking to unite and enhance much of the algae work underway in San Diego County is a new research consortium. It aims to help clear barriers to commercializing algae biofuels by identifying new algae strains and harvesting methods.
The San Diego Center for Algae Biotechnology was launched in 2008 with 16 founding partners from UC San Diego, the Scripps Institution of Oceanography, Salk Institute for Biological Studies, biofuel companies and more.
Until recently, "algae has been this complete backwater of scientific research," said the center's founding director, Steve A. Kay, who is also dean of biological sciences at UC San Diego.
"But we've all woken up with the realization that we are junking the planet."
Known as "nature's solar panels," the "amazingly clever little chemical factories" soak up carbon dioxide and sunlight, which is converted into oil through photosynthesis, Kay said.