US workboat engines are used for more than twice as long as previously estimated, enhancing the benefits of retrofitting engines according to new research.
The study, for enginebuilder consortium Diesel Technology Forum (DTF) and ecological lobby group Environmental Defense Fund, found that workboat engines have a service life of around 50 years, compared to the 23 years used by the US Environmental Protection Agency (EPA) to set its emissions reduction targets.
A longer service life means that older engines are replaced more slowly, resulting in 57% lower NOx reductions each year than those forecast by EPA. But it also increases the potential impact of installing new technology, DTF said, as upgraded engines will have a longer period in which to reduce emissions.
The groups are urging US states to repower vessels with more modern, cleaner engine technology. States can receive funding for repowering commercial workboats to reduce NOx under the US$2.9Bn environmental mitigation trust established by Volkswagen Group in the wake of the emissions test fixing scandal in 2015.
“Large engine repowers are more cost effective on a dollar-per-ton-of-emissions-
The study, conducted by Ramboll Environ, looks at engines with a cylinder displacement of 5-30 litres – loosely equivalent to a maximum power output of around 8 MW - classed as ‘category two’ engines by EPA. New marine diesel engines used have been required to meet EPA Tier 4 emissions standards since 2015. But DTF said that the cost and downtime required to upgrade to new engines have likely delayed investments in the newest technologies.
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