Climos, a San Francisco-based company that hopes to reduce carbon dioxide by fertilizing the ocean, said Wednesday it is raising $10 million to $12 million in a second round of financing.

So far, about half of the funding has been committed, said Dan Whaley, founder and CEO of Climos, at the Dow Jones Environmental Ventures conference in San Mateo, Calif.

Whaley said he expects to close the round by the end of the year.

About two months ago, the company announced it had raised $3.5 million in its first round of funding (see Funding Roundup: Tesla, Ausra, Pythagoras and More). A conference pamphlet noted that Climos is aiming to raise between $8 million and $10 million, but during his presentation Wednesday, Whaley said it is seeking more. The company previously said it would raise up to $14 million, according to Earth2Tech.

Climos plans to fertilize the ocean with iron to grow more plankton that would, in turn, absorb more carbon dioxide.

But finding a way to profit from plankton can be tough. Foster City, Calif.-based Planktos was forced to pull planned field tests earlier this month due to a lack of funds, according to the New York Times.

Climos' business plan, at least initially, is to sell carbon credits to large companies, Whaley said.

But first, the company has to prove the effectiveness of its approach. And that’s where the cash comes in. The company plans to spend the money on its first project, somewhere in the middle of the ocean.

To do this, Climos will need to get a permit from a signatory nation of the London Convention, which aims to control and prevent marine pollution.

Getting the permit might not be an easy process. Environmentalists – along with some marine and climate scientists – have opposed such plans in the past, citing unevaluated risks, according to The New York Times. Aside from funding troubles, Planktos blamed its shutdown on a “highly effective disinformation campaign waged by anti-offset crusaders.”

If Climos gets a permit, it plans to pour iron over a swath of ocean 100 or 200 kilometers long, Whaley said. The company didn’t say exactly where it would target its fertilization.

Previous Climos tests have shown the company's technology can sequester between 25 and 30 tons of carbon dioxide per square kilometer of ocean surface, according to Whaley.