This article seeks to focus on how “greening” of existing standby diesel generators can be achieved and what options could be available as technology develops in the future. The author, Geoff Halliday from WB Power Services considers how a cohesive strategy is required if a business is to be successful in reducing emissions from its existing infrastructure. He examines why a sustainability strategy must have equal importance with other business imperatives and how collaboration between all elements that are involved is critical.
One effective way to start reducing emissions is through the introduction of a catalytic converter into the diesel generator exhaust gas stream. This can lesson CO2 emissions by between 20% and 40% (dependant of the unit fitted), with the converter reaching its optimal operating temperature before it is effective. The increase in the availability of Hydrotreated Vegetable Oil (HVO) in the last two or three years has resulted in many of the larger engine manufacturers approving its use across several engine ranges. Some manufacturers are even opening this to engines on more recently installed generating sets too (checks need to be made with the engine manufacturer for suitability). In addition to ensuring that HVO is readily available locally to ensure security supply, it is also worth noting that some manufacturers are offering solutions that will reduce running of generating sets for regular maintenance and testing.Whilst there is a significant push to reduce CO2, any strategy should give due consideration to other pollutant sources. As well as the engine itself, exhaust gas after treatment systems are used to reduce other emissions such as NOx, PM, HC many of which can be retro fitted to existing installations. These include:
We now need to turn our attention to any existing solutions, and those that can be built into new infrastructure which are in the early stages of development. In support of this, we should also consider any limiting factors. These include:
Clearly there are several pros and cons associated with the potential current and the future use of these products, including the environmental impact in production and the operational constraints, such as:
HVO and hydrogen are a current and potential future fuel to power standby generation. We now look at the care that needs to be taken in the selection and sourcing of these alternative fuels.
HVO is a liquid fuel that is synthesized from waste vegetable oils or animal fats using a special hydrotreatment process. Unlike first-generation bio diesels, HVO is an entirely renewable energy source that does not impact crop resources, and it can translate into up to 90 percent fewer greenhouse gas emissions over its entire lifecycle. Some HVO however is manufactured either as an entirely “new” product or a mix of products. Such products use newly harvested oils such as sunflower or palm oils which in turn remove these from the food chain. In the case of palm oil, production is known to be responsible for widespread deforestation.
Fuel cells or hydrogen fuel combustion engines can only really be considered ‘green’ if the hydrogen used to power them comes from sustainable sources such as renewables, nuclear, or biomass. At present, though, around 95 percent of hydrogen comes from natural gas – and making 1kg of this ‘grey’ H2 emits 11 tons of CO2. ‘Blue’ hydrogen is produced the same way, but the CO2 is captured and stored – but suitable storage sites are few and far between, so availability is limited. The long-term solution comes with “green” H2 made from renewable energy such as solar. This approach is a few years away from being practically available at scale, and the H2 produced is hard to store in bulk without significant investment in associated infrastructure.