Internal combustion engines running on diesel or gas are widely used in power generation, but the exhaust emissions from these can be a problem. There are three main difficulties, as follows:
- Sensitive locations, such as a city centre, outdoor event etc.
- Intensive operation, in which case the quantum of the pollutants emitted may be significant
- Large number of standby generators in countries where the grid is not reliable
As part of strategies to improve air quality, many countries have introduced regulations limiting emissions from generators.
Most new generators are not designed to comply with any stringent emissions limits, and therefore it is often necessary to retro-fit them with exhaust gas aftertreatment technology, such as catalytic converters, diesel particulate filters or selective catalytic reduction (SCR) systems.
In addition, there is a large number of existing generators, some of which are decades old, and it is often worthwhile to clean these up if they are still in good condition.