Smokestacks – the bane of climate change activists – belch planet-warming carbon dioxide (CO2) while the coal and natural gas plants they rise from provide the cheap electricity that modern society relies on. But what about smokestacks out at sea?

Ships more typically enter pollution discussions on account of oil spills, such as the infamous Exxon Valdez wreck that took place 20 years ago tomorrow. But as concern over the threat of global warming grows, attention is turning to the ocean bound fleet of smokestacks that ferries about 90 percent of global trade and coughs out 4 percent of worldwide fossil fuel greenhouse gas emissions, Reuters reports.

Enter Ecospec, a Singapore-based firm that has recently unveiled a patented technique, called CSNOx that removes three-quarters of the carbon dioxide, the most common greenhouse gas, from ships’ tailpipes. Ships’ fossil fuel consumption also unleashes sulfur dioxide (SO2), a prime ingredient in acid rain, and nitrogen oxides, which can form toxic compounds as well. CSNOx reportedly also removes 90 and 80 percent of these other unwanted emissions, respectively.

How does it work? According to Ecospec, its smoke-cleaning system slurps seawater onto the ship where it undergoes electrolysis, raising the water’s pH from a typical 8.1 to 10. (pH is the measure of acidity or alkalinity of a solution; the lower the pH, the more acidic the liquid.) Fumes from fuel combustion pass through this alkaline seawater in exhaust tunnels, where the gases and the liquid react, forming new compounds that do not escape with the emissions. The filtering water is then processed in an onboard tank before being released back into the ocean.

The company claims this released water contains no secondary pollutants. As a bonus, the returned seawater remains more alkaline than normal – perhaps not a bad thing as the oceans absorb massive amounts of man-made carbon dioxide that in turn are making them perilously acidic for shellfish and other marine creatures.

Retrofitting ships with the CSNOx system is expected to cost between $500,000 and a million per vessel, according to Reuters. Interested firms have reportedly deluged Ecospec with inquiries since it was unveiled.

What works well at stemming sea emissions could also, of course, work well on land, where 90 percent of anthropogenic greenhouse gases are generated, Reuters reports. Potential beneficiaries of Ecospec’s technology include coal- and gas-fired power stations, garbage incinerators, and steel and paper mills.

Cargo ship. Image Credit: NOAA