#5 The nitrogen-debate: NOx in the construction field

As the news outlets have indicated, the construction industry is in a precarious position at the moment. Many construction projects are on hold or have been canceled due to the verdict of the 29th of May 2019 in regards to PAS, even though there is a high demand for more houses. At the end of 2019, emergency legislation was passed by the government, which should open up possibilities for construction [1]. Even though no concrete measures have been taken yet, it looks like only housing and certain infrastructural projects will receive extra leeway in regards to NOx emission, leaving other types of projects in a difficult position.

To be able to start these other types of projects, innovations in the way we construct will be needed. However, the construction industry has been known for being stagnant in innovating their methods. Currently, most of the innovation required to decrease the NOx emission has been in the machinery used on the construction sites. An example of this is the use of tower-cranes connected to a power grid instead of mobile cranes power by diesel. Despite this, the availability of machinery with lower emissions is an issue. The electrical cranes are more expensive and are in high demand, making them economically unfeasible or unavailable for some projects.

The purchase of heavy machinery with newer engines and lower emission rates is thus expensive, making the machinery scarce. This leads to the use of old machinery because their purchases are still being written off or are turning profitable, which causes a bottleneck in available and wanted machinery. However, just using the newest machinery with the cleanest possible engines is not the entire solution either. In terms of decreasing NOx emissions, the latest engines have reached their limit. Currently, engines are classified by construction year and are divided into Stages. These Stages each have their own emission rates. For example, a Pre-stage 100kW diesel engine from 1985 has a NOx emission factor (EF) of 11.8 gr/kWh [2]. This has gradually improved over the years. A Stage III (2007 onwards) and Stage IV (2014 onwards) 100kW diesel engine have an EF of 3.3 gr/kWh and 0.4 gr/kWh respectively [2].

Additionally, Stage V engines (2020 onwards) will have a NOx EF of 0.4 gr/kWh. Although engines have improved in other categories for Stage V, the NOx emission remained the same since 2014, indicating a need for other methods to decrease the emission. Electrical machinery might seem like the obvious next step. However, the required size of battery packages and charging times for heavy machinery would be unfeasible in the current form of the technology.

Another way of decreasing NOx emissions during construction is by reducing the amount of kWh required. This could be done by creating new construction methods, such as lighter buildings leading to lighter machinery used or off-site assembly. This is most likely the area in which the industry will need to innovate. However, reducing NOx and NH3 emissions should not be the “be-all and end-all.” Some natural habitats are nitrophilic, while others are nitrofobic. As nitrogen will always be a part of the atmosphere, an effort to actively maintain the natural habitats thriving on lower emissions should be made. In the past (pre-industrialized society), more ‘maintenance’ was done on these habitats, for example, because these had active grazing by herding animals. This interference by humans is what created these nitrofobic habitats in the first place, according to the memo by Staf [3]. After all, the Netherlands would still mostly be swamps and forests otherwise. However, funding for this maintenance has been low, leading habitats to deteriorate further over time. The new emergency legislation has provided faster procedures to allow this maintenance. To help with this maintenance, construction companies could offer assistance to habitats near their projects to clear the space for the possible deposition it might create. However, this would result in additional development costs for projects, which might make projects economically unattractive.

In conclusion, there are some steps that the construction industry has to make. Old engines should be replaced with Stage IV engines. Additionally, construction methods need to be innovated and more maintenance should be done on nitrofobic habitats.

 

[1] “Regels voor de aanpak van de stikstofproblematiek in relatie tot natuur,” eerste kamer.nl, 05-12- 2019 [Online] Available: https://www.eerstekamer.nl/behandeling/20191205/gewijzigd_voorstel_van_wet [Accessed 20 January 2020]
[2] J.H.J. Hulskotte and R.P. Verbeek, “Emissiemodel Mobiele Machines gebaseerd op machine verkopen in combinatie met brandstof Afzet,” November 2009
[3] Stichting Agri Facts, “Toetsing ’Spoedwetgeving’,” 02-12-2019 [Online] Available: https://stichtingagrifacts.nl/wp-content/uploads/2019/12/Paper-STAF-02-12-2019.pdf [Accessed 20 January 2020]