Tech approaches to the reduction of diesel generator emissions

A surge in the number of extreme weather events around the world has given renewed impetus to government efforts to address climate change, and businesses globally are under increasing pressure to comply with environmental regulations.

Southeast Asia is one of the world's most climate-vulnerable regions but, at the same time, has been heavily dependent upon fossil fuels to underpin the strong economic growth experienced in recent years. With the rapidly increasing spotlight on decarbonization across the region, organizations in all sectors are now implementing sustainability plans which seek to reduce their use of fossil fuels.

As an emitter of CO2 and other gases, the diesel generator is an obvious target for emissions-reduction regulation. However, there is currently no obvious, cost-effective solution which can scale to deliver the same level of reliability and performance as the diesel generator. In the medium term, while alternative technologies evolve, the diesel generator is likely to remain an essential component of many mission-critical energy systems, delivering emergency backup power in as little as 10 seconds.

Ongoing initiatives are therefore focused on reducing the environmental impact of the generator.

Key considerations when selecting a generator
Factors such as output power are obviously key when selecting a diesel generator, but it is equally important to ensure that any procurement complies with local regulations.

Eight out of ten countries in Southeast Asia have recently set carbon neutrality goals, with seven either considering or already implementing carbon pricing mechanisms. At the same time, Indonesia, Singapore, Thailand, and Vietnam have all committed to material reductions in emissions by 2030.

In Singapore, the National Environment Agency (NEA) has recently signed a MoU with the USA's Environmental Protection Agency (EPA), formalizing a framework of cooperation between the two agencies. The MoU covers areas including solid waste management, air quality management, decontamination/management of chemical, biological, and radiological incidents, and environmental governance. Also in Singapore, the Ministry of Trade and Industry has only recently ended a moratorium on new data centre installations, replacing it with a set of restrictions which mandate "best-in-class" resource efficiency levels.

While regulations play a key role, customer attitudes are equally important in today's market. More and more organizations are demonstrating a proactive approach to sustainability, and, for them, regulatory compliance is often not enough. Many want to go above and beyond the demands of the legislation with the greenest solution or the best available technology.

It's useful, therefore, to understand the technologies which are available to reduce the environmental impact of the diesel generator.

HVO: a renewable fuel
Hydrotreated vegetable oil (HVO) presents one of the biggest opportunities to reduce diesel generator emissions. A product of the hydrogenation of vegetable oil, HVO, also known as green diesel or renewable diesel, reduces net CO2 emissions from a diesel generator by up to 90%. To put this into perspective, the emissions from a typical 1000-kilowatt generator running for 100 hours per year on conventional diesel are equivalent to 16 cars per year. The emissions from the same generator running HVO are equivalent to less than two cars per year.

HVO can be used as a direct replacement for conventional diesel with no modifications required, either to the engine itself, to the maintenance schedules, or any related infrastructure. Using HVO does not have any adverse impact on generator availability since transient response times with HVO are very close to those of conventional diesel. Similar in grade and quality to conventional diesel, HVO is wholly compatible with standard fossil diesel and can be blended in any mix. It is also very easy to store and takes a long time to degrade, so can be kept for many years.

Unlike first and second-generation biofuels, HVO does not impact agricultural land use since it is made from waste products, such as vegetable oils, animal fats, and used cooking oils. In the near-to-medium term, it will also be possible to make it from photosynthetic organisms such as algae.

Although HVO is currently more costly than traditional diesel, prices are expected to drop as multi-million-dollar investments are being made in the global supply chain, and the availability of HVO is increasing. In Southeast Asia, new and expanded production facilities are underway in Singapore and Malaysia, and more production plants in the region are set to follow. Having supplies closer to the end user will further reduce carbon emissions and costs as transportation miles are reduced.

Emission reduction technologies
Manufacturers of diesel generators are responding to market sustainability expectations and regulatory requirements by continually improving the environmental performance of their products. Increasingly sophisticated emissions reduction technologies are evolving to ensure that the diesel generator continues to play a key role in reliable energy systems.

These technologies can be grouped into in-cylinder and after-treatment categories, where the former reduces pollutants emitted by the engine and the latter reduces pollutants in the engine's exhaust stream. In-cylinder technologies such as EGR (exhaust gas recirculation) and combustion optimization maximize engine efficiency, while after-treatments, including Selective Catalytic Reduction (SCR) and Diesel Exhaust Fluid (DEF), reduce NOx emissions to negligible levels.

There is a clear trade-off between emissions reduction and cost optimization, and the selection of the appropriate emission reduction technologies will be driven by current and anticipated regulations, as well as the customer's sustainability goals.

Maintenance schedule optimization
Generators which are used to provide backup power in the event of an outage spend most of their life in an idle state. When an outage DOES occur, however, they must be ready to operate and must "kick in" within seconds to ensure no interruption to the power supply.

To ensure this constant state of readiness, the generators must undergo a systematic maintenance program, including regular periods of operation. These exercises are traditionally conducted under load to reduce "wet stacking", where unburned fuel accumulates in the engine's exhaust system, leading to excessive wear and, ultimately, damage and early engine failure.

Over the course of a year, these maintenance cycles contribute significantly to the emissions from the generator and also increase the cost of ownership to the end customer. Generator manufacturers are, therefore, developing products which need fewer annual running hours and reduced loads during maintenance. Current sustainable maintenance programs allow for extended exercise intervals and also testing under no-load conditions, resulting in annual emissions reductions of up to 69% when compared with testing at a 30% load.

Conclusions
Manufacturers of diesel generators have responded to environmental pressures with a range of technological innovations which significantly reduce emissions over the lifecycle of the generator. Most importantly, while demonstrably reducing emissions, these measures have minimal impact on generator performance characteristics such as engine power or transient performance.

Users of diesel generators within Southeast Asia can selectively choose from the range of technologies outlined above to ensure that they meet regulatory and corporate emissions targets while optimizing cost and minimizing impact on performance.