Reducing tailpipe emissions is an important responsibility for operators of diesel applications. Air quality in urban areas remains a significant challenge, even though standard fuels and vehicle technologies have developed over the last few decades.
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A recent University of Oxford study found that exposure to pollutants such as PM2.5 (small particular matter) and nitrogen oxides (NOx) is linked to an estimated 40,000 early deaths in the UK each year. Cars and vans generate £6 billion per year in health damages alone, and diesel is the main culprit. Special working environments, such as mines, construction sites or tunnels, can be particularly challenging.Prema HVO is a cleaner-burning alternative to conventional diesel. Its tailpipe emission levels are proven to be lower, which means it is cleaner for your workers, your local community and the environment at large.
Prema HVO has undergone independent, empirical testing to provide an accurate understanding of the real-world emissions that leave your tailpipe.
Comprehensive exhaust emission tests were performed on 36 trucks and buses or their engines, along with several passenger cars in vehicle and engine test beds. They were transient tests, meaning that they simulated real driving conditions and driving cycles, including acceleration phases.
The tests found that Prema HVO:
You can see a summary of the empirical test results compared to conventional diesel (EN590) below:
Please note that the CO2 results are based on vehicle tailpipe emissions alone, not the origin of the carbon in the fuel itself (be it renewable or fossil). In other words, this CO2 only corresponds to the ‘tank-to-wheel’ part of the fuel’s lifecycle. Please see our Greenhouse Gas Emissions explainer for more detail on how Prema HVO offers significantly lower greenhouse gas emissions than conventional diesel over its full lifecycle.
Prema HVO reduces the number of particulates across all size classes, not just the more well understood PM2.5 and PM10 varieties. This is particularly important as stakeholders are becoming more aware and concerned about the effect of much smaller ‘nanoparticles’ on human health. Recent research suggests that these tiny toxic substances could be a major cause of illness and death.
This graph shows the distribution of particulate sizes emitted by a bus using Prema HVO compared to conventional diesel:
In engine technology, there is a well-known trade-off curve between NOx and PM emissions, whereby lowering NOx emissions results in higher PM emissions and vice-versa.
In our testing, differences between individual engines have been so great that some truck or bus types showed a reduction in PM of up to 47% with only a negligible or slightly increased effect on NOx. On the other hand, in some engines NOx is reduced more – up to 14% – and PM less. In any case, as the graph below demonstrates, Prema HVO moves the trade-off curve of the base engine towards the origin (the desired effect for every engine designer).
As the graph shows, tailpipe emissions depend on various other factors as well as the fuel, such as the fuel injection system, engine calibration, the exhaust gas recirculation (EGR) system, and so on. The total effect of Prema HVO depends on these other factors.
IMPORTANT: Not all HVOs are alike…
The tailpipe emissions of HVO are also dependent on what the HVO is actually made from, and unfortunately, not all HVOs are alike. Some HVOs are made from one type of oil, whereas others are made from multiple types.
Prema HVO is made from one category and one category alone, hydrotreated used cooking oil. It is supplied by only one supplier, Neste. In other words, it is a single source fuel from a single supplier, which is clearly evidenced by its ISCC certification. Having this chain of custody is invaluable for credible and accurate tailpipe emission monitoring. Without it, you cannot be sure what type of HVO you are using.
As well as 100% neat HVO, Prema Energy can offer Prema HVO/fossil diesel blends to provide customers with the benefits of HVO at a lower price point.
When Prema HVO is used as a blending component, particulate and NOx emissions are reduced quite linearly according to the blending ratio. Typically, even small blending percentages of Prema HVO will reduce regulated emissions, especially hydrocarbons (HC) and carbon monoxide (CO). However, more important is the reduction in NOx and PM, which are the key pollutants from diesel vehicles.
This graph summarises the effects on emissions as the blending ratio of HVO increases:
When Prema HVO was blended with standard diesel to produce a premium EN590 diesel fuel, Neste Renewable Diesel recorded the following tailpipe emission benefits across some tens of percents of the blend in passenger cars:
An example of a passenger car with common rail fuel injection, EGR and oxidation catalyst, but without a particular filter, is presented below. It shows high NOx reduction and no statistically significant influence on PM.
These tests were made using factory engine mappings. The benefits could be increased even more if improved strategies for controlling EGR are put in place.
Practically all new diesel cars and heavy-duty vehicles today are equipped with a diesel particulate filter (DPF), which serve to reduce particulate emissions. The lower engine-out particulate emissions resulting from the use of Prema HVO offers additional benefits in this area since exhaust back-pressure is lower and there is no need to clean the filter as often (Prema HVO is practically free of ash-forming components). This can even lead to slightly lower fuel consumption with Prema HVO compared to other fuels, if the control system of the particulate filter is able to detect actual soot build up according to the fuel quality used.
We hope this helps to clarify how Prema HVO can be used to reduce tailpipe emissions. If you like to discuss any aspect of this further, we are more than happy to answer your questions.