Could new technology help the ocean – already a vast carbon sink – adapt to combat global warming without causing the acidification that threatens ocean life?

That could be a strategy that C12 Energy is looking at, if scientific research from the stealthy carbon capture startup's co-founder are any guide.

C12 has landed $4.5 million from Sequoia Capital and other undisclosed investors, according to VentureWire. While the Cambridge, Mass.-based startup has remained quiet about its plans, president and chief scientist Kurt Zenz House co-authored a 2007 study that might offer some clues. 

The study, "Electrochemical Acceleration of Chemical Weathering as an Energetically Feasible Approach to Mitigating Anthropogenic Climate Change," lays out a means of making the ocean more alkaline by reducing its acid content, in a process "equivalent to the electrochemical acceleration of the Earth's natural chemical weathering process." 

In essence, the study proposes using electrolysis to convert weaker carbonic acid in the oceans into hydrochloric acid - "the engineered process accelerates the weathering kinetics to industrial rates," the study states. That could speed the rate at which silicate rocks –basalt, granite and other minerals that make up most of the Earth's crust – absorb the acid from the ocean.

"The increase in ocean alkalinity resulting from the removal of HCl causes atmospheric CO2 to dissolve into the ocean where it will be stored primarily as HCO3 without further acidifying the ocean," the study states. Atmospheric carbon dioxide is being absorbed by the ocean already, causing it to become more acidic - and that is leading to problems for coral reefs, giant squid and other ocean life, scientists say.

Undertaking such a vast engineering project would be daunting, to be sure. It's the equivalent of building about 100 plants the size of major sewage treatment facilities to capture about 3.7 gigatons of carbon dioxide per year, the study states.

"Our current estimates indicate that running the process described here at scales sufficiently large to impact the earth's climate is unlikely to be commercially viable in the near future," the study says.

But it's possible that "the marginal cost for CO2 reduction will become high enough to make the process discussed here economically competitive," the study adds, perhaps by using energy sources too far from population centers to be useful for human energy needs. 

None of this is to say that this is what C12 Energy is working on, of course. Company CEO Justin Dawe told VentureWire little about the company's plans, other than that the $4.5 million investment should cover the company's expenses for the next three years and that commercialization would be several years away.

Commercialization would also depend on putting a price on carbon, Dawe told VentureWire. That's a common refrain among companies seeking to capture carbon dioxide, whether at the sources where it's produced or through more global means.

Whether it's better to price carbon through a cap-and-trade system like Europe has had since 2005, or through a direct tax on carbon emissions, is a topic of increasing debate. Europe's cap-and-trade program has seen its share of problems.

President Barack Obama has said he wants a carbon cap-and-trade system to help reach his goal of cutting greenhouse gas emissions to 80 percent below the 1990 levels by 2050, but prominent people – from former vice president and Nobel laureate Al Gore to ExxonMobil CEO Rex Tillerson – have said a carbon tax might be more direct (see Carbon Tax a Better Idea?).

Capturing carbon dioxide at coal-fired power plants – the largest single source of man-made greenouse gas emissions – is technically doable but not commercially viable right now, its proponents say (see Clean Coal's Chicken and Egg Problem, Canada to Beat U.S. to Carbon Storage and Vattenfall to Trap Carbon Emissions.)

Companies seeking alternative ways to engineer the ocean to better absorb carbon dioxide haven't fared that well of late. Planktos, which wanted to seed the ocean with iron to accelerate plankton growth (plankton, like other plants, absorb CO2 and emit oxygen), gave up on its plans last year. Climos, another startup with a similar idea, said it raised $3.5 million in early 2008, but hasn't updated the world on its efforts to raise $10 million to $12 million more since then. 

Then there are a host of ideas on how to alter the atmosphere to reflect more sunlight away from the earth and slow global warming that way. But scientists say the scale and cost of such proposals makes them far from a practical reality today.