In 2020, the Environmental Protection Agency (EPA) granted regulatory relief to boatbuilders facing Tier IV requirements for engines over 800hp. According to EPA regulations, any engine over 800 hp would have had to meet strict Nitrogen Oxide—NOx—emissions rules, but on many vessels, it just couldn’t be done. The size of the available solutions, which called for large truck-based SCR systems and additional tankage for the DEF used in those systems, won’t fit on smaller vessels. Added to the problem is the fact that SCR cannot be retrofitted on existing engines.

Walt Schulz, CEO of STec Technology Inc., in New Bedford, MA, believes that the regulatory relief will not go on forever, and that he has the solution. “Our system attaches to an existing engine, fits in the same footprint as a regular exhaust system and reduces NOx by 82 percent,” says Schulz. “It also reduces carbon dioxide, and we’re trying to get that reduced by 20 percent. We’re close.” STec has received validation grants from the National Science Foundation and the Mass Clean Energy Center plus private equity investment.

The STec system uses high volume seawater for wet exhaust systems and converts dry stack systems to wet exhaust. According to Schulz, his company’s patented Reactive Cyclic Induction (RCI) relies on seawater as the primary catalyst along with calcium chloride, sodium hydroxide and other reactive elements. These elements are mixed with the exhaust gases by means of a rotational helix screw in the exhaust system, and to this mix the STec system applies low voltage DC electric current that creates electro-emulsification for molecular acceleration. The result turns poisonous NOx into harmless nitrogen and oxygen at the transom discharge. 

Another big problem that STec system solves is heat - Schulz points out: “In a truck the heat generated by the SCR system, which can go as high as 700 to 800 degrees Fahrenheit, can be dealt with because you’re going down the highway and all that air is blowing by. But in a vessel’s engine room it’s a different story.”

Schulz developed the system when Bill Ramos, STec’s COO, asked if there was a system they could use in a retrofit on a 45-foot Shannon built by Schulz. “There was none,” says Ramos. “You had to buy the system and the engine together. If the engine was $450,000, the SCR was $225,000. You can’t tell fishermen that if they want to move to Tier IV not only do they have to buy a SCR system, but a whole new engine too.” 

Schulz, a marine engineer and naval architect who founded Shannon Boat Company in Rhode Island, went looking for answers in existing research. “Our goals are to have a system that can replace old systems without creating backpressure or having to monkey around with an engine’s fuel management system, and possibly void the warranty.” 

But while he feels that he is close to meeting those goals, Schulz still faces some challenges. “The problem is consistency,” he says, noting that at differing RPM’s the precise mix of elements needs to change accordingly. “At higher RPM’s you’re going to have more NOx, and so you need to have more elements to convert that to nitrogen and oxygen. We’re working on getting that in sync in all loading conditions.” 

In addition, the team at STec is still trying to get the carbon dioxide levels down. “I know, a lot of people might think it’s unlikely that a boat builder like me from New Bedford can solve this problem, but we’ve got the NOx down to the requirements, and we’re going to get the CO2 down too.”