Traffic & Transport
Anna van Buerenplein 1
2595 DA Den Haag
P.O. Box 96800
2509 JE The Hague
The Netherlands

TNO report
TNO 2021 R10221

www.tno.nl

Real-world emissions of non-road mobile
machinery

T +31 88 866 00 00

Date

11 February 2021

Author(s)

R.J. Vermeulen
N.E. Ligterink
P.J. van der Mark

Copy no
Number of pages
Number of
appendices
Sponsor

2021-STL-REP-100337773
40 (incl. appendices)
1

Project name
Project number

Dutch Ministry of Infrastructure and Water Management
PO Box 20901
2500 EX THE HAGUE
The Netherlands
I-W HD 2020 NRMM
060.42502

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© 2021 TNO

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Samenvatting
Mobiele werktuigen en stationaire bronnen worden hoofdzakelijk door
dieselmotoren aangedreven en dragen daardoor bij aan opwarming van de aarde,
luchtvervuiling en stikstofdepositie. Over het algemeen is maar heel weinig bekend
over de praktijkuitstoot van mobiele werktuigen en stationaire bronnen op
bijvoorbeeld bouwplaatsen. Daarnaast is er ook maar weinig bekend over de inzet
van deze machines. In opdracht van het Ministerie van Infrastructuur en Waterstaat
heeft TNO daarom een emissiemeetprogramma uitgevoerd aan een selectie
mobiele werktuigen en stationaire bronnen, zoals graafmachines, laadschoppen,
pompen, generatoren en een koelaggregaat voor wegtransport.
De gegevens die worden verzameld in meetprogramma’s vormen de basis voor
de vaststelling van de officiële getallen voor praktijkemissies – de zogenaamde
emissiefactoren – die TNO jaarlijks oplevert. Emissiefactoren worden gebruikt op
landelijk, regionaal en gemeentelijk niveau als input voor rekenmodellen voor
luchtkwaliteit, emissieverspreiding en stikstofdepositie (EMMA en AERIUS), en
voor de beoordeling van huidig en voorgenomen beleid. Deze getallen vormen
tevens de basis voor de nationale en internationale rapportages over de emissies
(ER rapportages en GCN/GDN).
Er zijn langdurige praktijkmetingen verricht om inzicht te krijgen in de emissies en
het gebruik van de machines tijdens hun dagelijkse inzet. De metingen zijn gedaan
aan een aantal zware bouwmachines, maar ook aan lichtere machines zoals een
minigraver en een koelaggregaat zoals gebruikt in de transportkoeling. Daarnaast
zijn ook verkennende metingen verricht aan stationaire bronnen zoals pompen en
aggregaten. De werktuigen en machines voor het meetprogramma zijn
geselecteerd uit werktuigparken van Nederlandse ondernemingen en zijn
doorgemeten in de praktijkinzet zoals op bouwplaatsen.
Zware mobiele werktuigen
Resultaat van het onderzoek is dat de doorgemeten grote Stage IV en V mobiele
werktuigen (motorvermogen 56 - 560 kW) qua emissieniveaus een positief beeld
laten zien; de metingen laten zien dat door inzet van Stage IV en V motoren voor
zwaardere werktuigen de NOx-uitstoot in de praktijk fors kan afnemen van 2,8 tot
4,9 g/kWh voor Stage IIIB tot zo’n 0,8 en 0,5 g/kWh voor Stage IV en V.
Met aanpassing van het gedrag van de machinist (motor afzetten) kan de
NOx-uitstoot in de praktijk nog zo’n 30% extra afnemen. Met waardes van
0,5 tot 0,8 g/kWh ligt de NOx-uitstoot van de doorgemeten Stage IV en V
werktuigen in de praktijk nog wel boven de limiet voor de Stage IV en V norm
(0,4 g/kWh) die geldt voor een officiële motortest.
De ammoniakslip, die op kan treden bij Stage IV en V machines met een
SCR (Selective Catalytic Reduction) systeem, is laag met gemiddelde
ammoniakconcentraties in de uitlaat van 1 tot 8 ppm. Over een officiële motortest
mag voor Stage V de gemiddelde ammoniakconcentratie niet hoger zijn dan
10 ppm.

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Lichte mobiele werktuigen
De lichte mobiele werktuigen zijn qua emissies erg vuil, ook de nieuwste.
Voor kleine motoren (vermogen 8 - 56 kW) gelden per saldo zeer soepele emissieeisen voor NOx, inclusief Stage V, waardoor de NOx-uitstoot hoog is. Zo stoot een
Stage V mini-graver (18,5 kW) ongeveer net zo veel NOx uit als een zware Stage IV
of V bouwmachine. Ook de fijnstofuitstoot van de mini-graver is hoog omdat ook
de emissie-eisen voor fijnstof voor lichte motoren (vermogen < 19 kW) zeer soepel
zijn.
Stationaire machines
De doorgemeten stationaire machines (pompen en aggregaten), die aan oude en
erg milde emissienormen moesten voldoen, zijn allemaal erg vuil. Pompen en
aggregaten maken veelal veel draaiuren en vele vuile bronnen die veel uren
draaien stoten samen heel veel uit. Ook hangt het niveau af van de grootte van
een machine (maximum vermogen) en het actuele vermogen van een machine.
Een enkel groot aggregaat (770 KW) had tijdens bedrijf een NOx-uitstoot van
4,1 kg/u en stoot in dit geval net zoveel NOx uit als ongeveer 100 zware Stage IV/V
bouwmachines of 100 Euro VI vrachtwagens.
Twee stationaire machines, één met een stage V motor (>= 56 kW) met af-fabriek
SCR en één met een oudere motor met een retrofit SCR waren zeer schoon qua
NOx-uitstoot. Dit suggereert dat de Stage V-limieten voor zwaardere motoren
(>= 56 kW) en de gebruikte emissiereductie (SCR) ook effectief kunnen zijn voor
stationaire machines.
Koelaggregaat voor een vrachtwagen
De dieselmotor van een koelmachine op een koeltrailer stoot ongeveer 1,5 maal
zoveel NOx en tenminste 10 maal zoveel fijnstof uit als de Euro-VI trekker van de
koeltrailer. Hier bovenop komt het effect dat een vrachtauto veelal wordt uitgezet
als deze niet rijdt, terwijl een koelaggregaat vaak blijft doordraaien, ook als er niet
wordt gereden. Dit maakt de bijdrage van koelaggregaten aan luchtvervuiling nog
groter.
In dit onderzoek zijn metingen gedaan aan een beperkt aantal mobiele werktuigen
en stationaire bronnen op een bouwplaats. Daarmee is een eerste indicatie
gekregen van het niveau van de NOx- en fijnstofuitstoot in de praktijk.
Meer metingen zijn nodig om een compleet en betrouwbaar beeld te krijgen van
de uitstoot van deze erg brede categorie machines.

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Summary
Mobile machinery and stationary sources are mainly powered by diesel engines and
therefore contribute to global warming, air pollution and nitrogen deposition.
In general, very little is known about the real-world emissions of non-road mobile
machinery and stationary sources on, for example, construction sites. In addition,
little is known about the use of the aforementioned machines. On behalf of the
Ministry of Infrastructure and Water Management, TNO has therefore conducted
an emissions measurement program on a selection of non-road mobile machinery,
such as excavators, wheel loaders, pumps, generators and a cooling unit for
road transport.
The data collected in measurement programs form the basis for determining the
official numbers for real-world emissions - the so-called emission factors - that
TNO produces annually. Emission factors are used at national, regional and
municipal level as input for calculation models for air quality, emission dispersion
and nitrogen deposition (EMMA and AERIUS), and for the assessment of current
and proposed policy. These numbers also form the basis for the national and
international reports on emissions (ER reports and GCN / GDN).
Long-term field measurements were carried out to gain insight into the emissions
and the use of the machines during their daily operation. The measurements were
carried out on a number of heavy construction machines, but also on lighter
machines such as a mini excavator and a cooling unit as used in transport
refrigeration. In addition, exploratory measurements were also carried out on
stationary sources such as pumps and generators. The machinery for the
measurement program have been selected from machinery parks of Dutch
companies and have been measured in real-world use, such as on construction
sites.
Heavy mobile machinery
The result of the study is that the measured large Stage IV and V mobile machines
(power 56 - 560 kW) show a good picture in terms of emission levels:
The measurements show that the use of Stage IV and V for heavier implements
can significantly reduce NOx emissions in the real-world from 2.8 to 4.9 g/kWh for
Stage IIIB to around 0.8 and 0.5 g/kWh for Stage IV and V. By adjusting the driver's
behaviour (switching off the engine), the NOx emissions can decrease by about
30% more. With values of 0.5 to 0.8 g/kWh, the NOx emission of the measured
Stage IV and V machinery is in real-world still above the limit for the Stage IV and
V standard (0.4 g/kWh) that applies for an official engine test.
The ammonia slip, which can occur on Stage IV and V machines with an SCR
(Selective Catalytic Reduction) system, is low with average exhaust ammonia
concentrations of 1 to 8 ppm. On an official engine test for Stage V, the average
ammonia concentration should not exceed 10 ppm.

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Light mobile machinery
The light mobile machinery are very dirty, including the newest ones. For small
engines (power 8 - 56 kW), very mild emission requirements for NOx apply, also for
Stage V, which means that NOx emissions are high. For example, a Stage V mini
excavator (18.5 kW) emits about as much NOx as a heavy Stage IV or V
construction machine. The particulate matter (PM) emissions of the mini-excavator
are also high, because the emission requirements for PM for light engines (power
<19 kW) are very mild.
Stationary machines
The measured stationary machines (pumps and aggregates), which had to meet old
and very mild emission standards, are all very dirty. Pumps and generator sets
often run for many hours a day. Many dirty sources that run for many hours together
emit a lot. The level also depends on the size of a machine (maximum power) and
the current power of a machine. A single large generator set (770 kW) had a NOx
emission of 4.1 kg / h during operation and in this case emits about as much NOx as
100 heavy Stage IV / V construction machines or 100 Euro VI trucks.
Two stationary machines, one with a stage V engine (>= 56 kW) with factory SCR
and one with an older engine with a retrofit SCR, were very clean in terms of NOx
emissions. This suggests that the Stage V limits for heavier engines (>= 56 kW) and
the emission reduction used (SCR) may also be effective for stationary machines.
Transport cooling unit for a truck
The diesel engine of a refrigeration machine on a truck trailer is 1.5 times as dirty in
terms of NOx emissions and at least 10 times as dirty for particulate matter as the
Euro-VI truck driving in front of it. On top of this is the effect that a truck is often
switched off when it is not moving, while a refrigerated trailer often continues to run,
even when it is not being driven. This makes the contribution of refrigerated trailers
to air pollution even greater.
In this study, measurements were carried out on a limited number of mobile and
stationary machinery on construction sites. This provides a first indication of the
level of NOx and particulate matter emissions in real-world use. More
measurements are needed to get a complete and reliable picture of the emissions
of this very broad category of machines.

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Contents
Samenvatting ........................................................................................................... 2
Summary .................................................................................................................. 4
1
1.1
1.2
1.3
1.4

Introduction .............................................................................................................. 7
Background................................................................................................................ 7
Goal and objectives ................................................................................................... 8
Approach ................................................................................................................... 8
Structure of this report ............................................................................................... 9

2
2.1
2.2
2.3
2.4

Methodology .......................................................................................................... 10
Programme overview ............................................................................................... 10
SEMS, Smart Emissions Measurement System ..................................................... 10
Testo 350 gas analyser ........................................................................................... 13
Particulate matter..................................................................................................... 13

3
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
3.10

Measurement results ............................................................................................. 15
Cooling unit for delivery truck .................................................................................. 15
Stage V mini-excavator ........................................................................................... 16
Stage IV wheeled excavator .................................................................................... 17
Stage IV wheel loader ............................................................................................. 19
Stage V wheel loader .............................................................................................. 21
Stage V Excavator ................................................................................................... 23
Particle number emissions ...................................................................................... 25
Overview long term measurements mobile machinery ........................................... 26
Impact of ‘stand-by mode’ on NOx emissions. ......................................................... 28
Generating sets and pumps .................................................................................... 29

4

Conclusions ........................................................................................................... 34

5

References ............................................................................................................. 36

6

Signature ................................................................................................................ 37
Appendices
A Overview of EU Stage norms

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1

Introduction

1.1

Background

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Non-road mobile machinery (NRMM) such as excavators, wheel loaders,
tractors and stationary machines such as pumps, generating sets and
transport cooling machines today are mainly equipped with diesel engines and
make a significant contribution to the emissions of air pollutants (NOx and
particulate matter). Locally, the emissions can lead to European standards for
air quality being exceeded and a negative impact on the living environment
(health and nitrogen deposition). Running on regular diesel the machines also
contribute to global warming.
Non-Road Mobile Machinery (NRMM) is the term used to refer to all machines
with a combustion engine that do not fall under the categories of road vehicles,
sea-going vessels or aircraft. In addition to construction machines, this group
also includes diesel trains, inland vessels and generator sets.
In order to reduce environmental impact, there are European emission
standards1 for NOx and particulate matter emissions from this group of mobile
machines. These requirements apply to the conditions of the type approval
test. In terms of emission limits the emissions legislation applicable to NRMM
lags behind that regulating emissions of road vehicles. In some categories,
the limits are still very mild or have been very mild for a long time until entry
into force of Stage V as of 2021. This means that in the coming years the fleet
still contains a lot of machinery with diesel engines without emission
abatement.
For NRMM there are concerns that the legislation does not adequately cover
emissions during normal use and emissions only have been optimized over
formal test procedures while in normal use the emissions can increase beyond
the level of the applicable limit. During in-service operation, for example on a
construction site, the NOx emission levels may deviate from the standard
(Sandström Dahl & Willner, 2015) and (Sandström Dahl & Willner, 2015),
(Ligterink, Louman, Buskermolen, & Verbeek, 2018), (Wisell, Jerksjö, Hult, &
Lindgren, 2018), (Desouza, Marsh, Beevers, Molden, & Green, 2020). On the
one hand, the emission control system can’t reach operating temperature when
running under conditions with low engine load, on the other hand, such
operational conditions often fall outside the limits of the applicable official test.
Also very little is known about the use of this machinery. Some categories such
as generating sets and pumps may run continuously. Another complicating
factor is tampering or even removal of the emission control systems or parts
thereof in order to save on operating costs (van den Meiracker & Vermeulen,
2020). For the machinery there is no periodic inspection. This means that new
machines that are put on the market and run for thousands of operating hours
over the lifetime are never inspected for proper emissions levels.

1

DIRECTIVE 97/68/EC, REGULATION (EU) 2016/1628

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For the Clean Air Agreement (Schone Lucht Akkoord, SLA), especially for
improving local air quality on construction sites and in urban areas.
The Ministry of Infrastructure and Water Management is investigating policy
options for further reducing of nitrogen oxides from combustion engines of
mobile machines.
Some examples of policy options for reducing nitrogen emissions from
combustion engines are:
 Improve EU source policy: tightening of EU standards, in-service or real
world emissions testing and monitoring, increasing the durability period,
and increase tamper resistance of emission control systems.
 Emission monitoring and periodic inspection: checking the presence and
correct operation of the particulate filter and the SCR system. Prevent
manipulation of emission control systems (e.g. Adblue killers) by the users,
ensure proper maintenance and repair.
 Stimulating the use of clean(er) techniques, for instance in tenders.
 Stimulating proper use of the equipment to reduce the emissions.
 Accelerated replacement of old machines.
Emissions data is needed to substantiate achievable effects of the policy
options. However, only few data is available of the usage patterns and the
real-world tail pipe emissions of the various categories of non-road mobile
machinery. Especially, little is known about emission levels of newer equipment
(Stage IV and V) and also little data is available from ‘forgotten sources’, such
as generator sets and pumps. Data is also needed for emissions modelling and
reporting (ER report, GCN/GDN, AERIUS, EMMA). In order to gain insight into
the effectiveness of the various policy options and to obtain data for the various
national emission models and pollution dispersion models, it is important that
there is a clear picture of the emissions of different types and different
generations of mobile machines in actual use.
1.2

Goal and objectives
The goal is to extend the existing small knowledge base of real-world
emissions of non-road machinery in the Netherlands and get a first insight in
the real-world emissions levels. This is done by measuring the tail pipe NOx
and particulate matter emissions and the usage patterns of a selection of
mobile machinery in actual use in the Netherlands, with a focus on newer
equipment (Stage IV and V) and the generally underexposed group of
stationary machines such as generating sets, pumps and transport cooling
units.

1.3

Approach
To obtain the required insight in the real-world emissions of non-road mobile
machinery, a measuring program has been defined with two objectives:
1.

Mobile machinery long term monitoring: On a number of machines
emissions were measured continuously in daily usage, up to several
months in time.

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2.

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For this programme, a Smart Emissions Measurement System (SEMS)
was installed in various machines. The selection of machines contains two
wheel loaders, (mini-) excavators and a cooling unit on a truck semi-trailer.
Stationary machinery spot measurements: On a construction site, spot
measurements were done on the stationary machines that were present
on the construction site such as generating sets, pumps, a light pole and
a drilling rig.

The engines of the machines are certified according various EU emissions
standards, from Stage II to V.
The SEMS measures autonomously the emissions of NOx, O2, NH3 and CO2
and fuel consumption during normal operation of the machines for a period of
several weeks up to a few months without interfering the user.
The emissions of generator sets and pumps were measured with a handheld
instrument and gravimetric PM measurement were performed by taking
samples from the tail pipes of the engines.
1.4

Structure of this report
The methodology of the measuring programme is discussed in chapter 2.
The results of the programme are discussed in chapter 3, followed by the
conclusions in chapter 4.

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2

Methodology

2.1

Programme overview

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For this testing programme six machines were selected for long term
measurement of NOx emissions. The machines comprise excavators, a mini
excavator, wheel loaders and a cooling unit as used in a semi-trailer for
cooling transport over the road. For the equipment, machines were selected
with engines certified according EU emission Stages IV and V. The cooling
unit uses a Stage II certified engine.
Because little is known about in-use emissions of stationary machinery, such
as generator sets and pumps, the second part of the testing programme was
executed at a construction site where spot measurements were done on the
machines running that day at the site.
An overview of the selected machines is shown in Table 1 below.
Table 1: Overview of the measurement campaigns and machinery. All machinery used diesel
engines running EN 590 diesel oil.

Testing programmes
1) Long term NOx, NH3 and
usage measurement
and PN measurement
on DPF equipped
machines
2)

Construction site spot
measurements: NOx,
particulate matter

Machinery
Wheeled excavator, Stage IV
Excavator, Stage V
Wheel loader, Stage IV
Wheel loader, Stage V
Mini excavator, Stage V
Trailer cooling unit, Stage II
4 Generator sets (19-770kW), Stage II to IIIA
1 Sewage pump, Stage IIIA
1 High pressure pump, Stage IIIA
1 Drilling rig, Stage V
1 Light pole, Stage II

2.2

SEMS, Smart Emissions Measurement System
SEMS is a sensor-based system developed by TNO [Heijne et al., TNO 2016a]
and is used in the programme to measure and analyse the tail-pipe
NOx emissions during daily operation and a range of vehicle/engine parameters
to be able to characterize the typical operation of the vehicles. In this way, for
the group of vehicles, weeks up to months of data was collected per vehicle.
The SEMS uses an automotive NOx sensor, an ammonia sensor, GPS and a
data-acquisition system to record the sensor data and data from the vehicle
and engine at a sample rate of 1Hz. The system can operate autonomously
and wakes up at ignition/key-on of the vehicle. The system can be stowed
away so that normal operation is not hindered by the measurement.
The recorded data is sent hourly to a central data server.

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Figure 1: SEMS. Left, calibrated NOx-O2 sensor mounted in the tail pipe. Right, autonomously
running data recording unit with hourly data transmission to a central server via
GPRS.

The raw data on the central server is post-processed automatically to filter and
check the data. Sensor output is corrected using sensor specific calibration
values. Mass-emissions and instantaneous engine power are calculated
combining sensor data (NOx and O2 concentration) and engine and vehicle
data such as manifold-air pressure, mass air flow, engine speed, fuel rate,
engine torque.
Accuracy
The concentration measurements can be converted to absolute mass
emissions, using different engine signals available on the CAN bus. When
concentration is multiplied with the exhaust gas mass flow, the total mass can
be determined. The inlet mass air flow has been the most accurate signal for
the purpose. The exhaust air flow requires a minor correction of a few percent
for the combustion products. This can be done using the measured oxygen
concentration.
In the absence of mass air flow, which was the case for the engines of the
machines tested in this programme, there are a number of alternatives to
determine the mass air flow. Special care must be taken of the alignment of the
concentration signal and the flow signal. Due to a mismatch of the peaks in the
concentration with the corresponding flow, uncertainties can arise. Further
down the exhaust line the measured concentrations are more smoothened than
directly after the engine, which limits this problem somewhat.
Two alternatives methods stand out. Given the inlet air temperature and the
pressure, the amount of inlet air can also be determined, using the cylinder
volume and engine speed. This turns out to be a stable method to determine
the exhaust mass flow. This method was used for the machines tested. For
smaller, faster engines, and in the case of high-pressure EGR, this method is
less suitable. A second method is a reconstruction of the exhaust mass flow
from the CO2 concentration and the fuel consumption from the CAN bus. The
second method shows a large variation, which lead to systematic deviations.
The source of the variation is, in part, the erratic fuel consumption itself.

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However, the time misalignment of the fuel consumption and the oxygen
concentration measurement, is probably also a large source of uncertainty. The
third element that may affect the uncertainty and bias of the fuel consumptionbased approach is the inherent mathematical uncertainty. A small part of the
exhaust gas flow, i.e., a few percent combustion products, is used to
reconstruct the remaining 95 % of the flow. Minor measurement errors are
therefore magnified.
In the correlation of the two approaches, one sees a large spread in the fuel
consumption-based method around the, more stable, speed-density method.
The variation is larger than the average, but bounded from below.
Consequently, the variation, which is more upwards than downwards, created a
bias on the average of about 20 -30 % above the true average. Comparing the
sums of the CO2 emissions from the speed-density method and the recorded
fuel consumption, shows, on the other hand, typically 5 % lower fuel
consumption from the CAN bus than the independent determination of the fuel
consumption, through the speed-density approach. The brake specific CO2
emissions can be calculated by using the CAN data engine torque and engine
speed to calculate the engines work. While broadcasted engine torque and
speed are in principle parameters with unknown accuracy these values in
combination with fuel consumption indicate a diesel engines efficiency.
The brake specific CO2 emission of a diesel engine is a rather stable value at
medium speed high torque which can vary some 20 % in relation to known
engine parameters such as displacement and the presence of turbo.
Large spread in data, and weak correlations, can therefore lead to apparent
inconsistent conclusions. When correlating the time-dependent results, the
skewed distribution will lead to an overestimation. At the same time
independent sum results can lead to the opposite conclusion. Independent
validation of the results is therefore essential for the appropriate confidence.
Correlation tests with a reference system with known accuracy is necessary to
further investigate possibilities to improve the calculation methods to derive
mass emissions using sensor- and CAN based data.

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2.3

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Testo 350 gas analyser
Instrument

Testo 350

Gases configuration

CO, NO, NO2, CxHy, O2, CO2 from O2

Device nr., Certificate nr.

230400 3506, 2002543

Figure 2: Testo 350 gas analyser used for the measurement of gas concentrations NO, NO2,
O2, CO, CxHy and CO2 (from O2) in the exhaust of stationary machines at a
construction site.

2.4

Particulate matter

2.4.1

Particle number concentration: NPET, Nanoparticle Emission Tester
Stationary measurements of the tail pipe particle number concentrations are
performed on machinery with a diesel particle filter (DPF). The results are used
to obtain an indication of the diesel particle filters (DPF) filtration performance.
The measurements are conducted during installation of SEMS on the
machinery. For the measurements, the particle number (PN) concentration in
the tail pipe is measured at idle or stand-by mode with the engine running
(600-800 rpm) and at a high constant engine speed (1500-2000 rpm).
Additionally, the ambient PN concentration is measured before and after the
exhaust measurements. The instrument used is an NPET model 3795 of the
manufacturer TSI. The instrument is meant to measure the solid particle
number concentration downstream the DPF in diesel exhaust and uses a
volatile particle remover to reduce semi-volatile and nucleation mode particles.

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Table 2: Specifications of the Nanoparticle Emission Tester, NPET.

Instrument
Model

NPET
3795

Range

1,000-5,000,000 1/cm3

Mode

Semi volatiles and nucleation mode particles are
evaporated and oxidized and therefore not counted

Detection efficiency

23nm: <50%
41nm: >50%
80nm: 70-130%
200nm: <200%
30nm C40 droplets: <5%

Response time
10-90%-10%
0-90%

2.4.2

<5 s
<10 s

Particulate matter mass: gravimetric on filter
Particulate matter mass emissions were measured from the exhaust of the
stationary machines on a construction site. Raw exhaust gas or diluted exhaust
gas is sampled from the exhaust. A continuous flow controlled by means of
mass flow controllers is drawn by a downstream pump through two parallel
40 mm filters, quartz and PTFE. A sample time of about two minutes is used.
The loaded filters are conditioned for several days until stable in mass.
Mass of the filters is determined before the measurement, during and after
conditioning. The difference is the mass of solid particulate matter collected
on the given filter medium.

Figure 3: Measurement set up for measurement of particulate matter gravimetrically. Left:
mass flow controllers for a stable sample flow and dilution. Right: filter holders.

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3

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Measurement results
In this chapter the results of the measurements are presented.

3.1

Cooling unit for delivery truck
The cooling unit is a common type seen on refrigerated semi-trailers. The unit
offers multi temperature zones. The units internal power source is a Stage II D,
2.1 litre Yanmar diesel engine without emission abatement system.
Stage II D (19 ≤ P < 37 kW) means a NOx limit of 8 g/kWh and a PM limit of
0.8 g/kWh. These limits haven’t been changed until Stage V which enters into
force end of 2021. This means that the in-use fleet of cooling units today still
mainly uses Stage II certified engines.
The NOx emission is 52 g/h, which is about 1.5 times the average NOx
emission of a Euro VI tractor with a 300 kW engine. Based on the assumption
that the unit would emit around the Stage II limit value (0.8 g/kWh) and using
emission factors for tractors it can be estimated that the PM emission of this
cooling unit would at least be 10 times higher than of a 300 kW Euro VI truck
engine.
When active, the cooling unit ran on average for about 11 hours a day.
For this engine the actual engine power could not be calculated from CAN bus
signals because this bus was not present. The power was modelled from the
CO2 emissions which were fitted to the max. output as provided in the engine
specifications and to the minimum output without any load. Still a certain
amount of uncertainty remains as the zero load point could not be determined
exactly.
During the tests the engine runs most in a low speed, low power setting of
about 20 to 30% of the maximum engine load.

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TNO test code

TK_SL

Brand, type

Thermoking, SLXi spectrum,
Engine: Yanmar, TK486V

Configuration

Cooling unit on semi-trailer

Engine power [kW], displacement [l]

25.3, 2.09 l

Emission Stage

II (D)

Emission abatement system

-

TA number

e13*97/68DA*2012/46KA*557*17

Total test period [days], days active [days]

206, 164

Total activity [hours], [hours/day]

1787, 10.9

Average power [%]

22

Stand-by [minutes/hour]

6

NOx [g/h], [g/kWh]

52, 9.5

Total NOx [kg]

92

CO2 [kg/h]

5.9

Total CO2 [t]

10.6

Fuel consumption [l/h]

2.2

Stage V mini-excavator
A mini-excavator was hired for a day and typical manoeuvres and work were
performed simulating normal operation. Hydraulics propel the machine, lift and
tilt the arm and bucket and rotate the cab. The hydraulics in turn are propelled
by a 1.5 litre Stage V NRE 2 (8 <= P < 19) 4 cylinder atmospheric diesel engine
without emission abatement system. The engines net power lies just below the
19 kW boundary and therefore just falls in Stage V category NRE v/c 2 which
has less stringent HC+NOx limits (7.5 g/kWh) than the Stage II NRE v/c 3 for
net power of 19 to 37 kW (4.7 g/kWh). With an easy NOx limit of 7.5 g/kWh no
emissions abatement system is necessary. This explains the relatively high
measured brake specific NOx emissions of this Stage V engine. The Stage V
NRE v/c 2 category with easy limits for PM (0.4 g/kWh) and the lack of a PN
limit also make that this Stage V engine does not require a diesel particulate
filter whereas for the category NRE v/c 3 (19 <= P < 37 kW) a filter would be
required to reduce the engines particulate emissions.

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TNO test code

KU_KX

Brand, type

Kubota, KX-027-4

Configuration

Mini-excavator

Weight [t]

2.6

Engine power [kW], displacement [l]

18.5, 1.498 l

Emission Stage

V (NRE v/c 2)

Emission abatement system

-

Fuel

EN590 diesel

Running hours

1716

Total test period [days], days active [days]

2, 2

Total activity [hours], [hours/day]

8.3, 4.2

Average power [%]

19

Stand-by [minutes/hour]

20

NOx [g/h], [g/kWh]

36, 10.2

Total NOx [kg]

0.3

CO2 [kg/h]

5.8

Total CO2 [t]

0.05

Fuel consumption [l/h]

2.2

Stage IV wheeled excavator
The Liebherr A914/916 is a very common excavator. The engine is a Stage IV
(R) using ‘SCR only’ to reduce the NOx emissions of the diesel engine and
uses no diesel particle filter. The Stage IV NOx limit of 0.4 g/kWh requires the
use of SCR. The PM limit of 0.025 g/kWh usually does not require a DPF.
The PM level can be kept below that level, when high pressure diesel injection
strategy is used and no EGR. For Stage IV, some manufacturers prefer to
apply DPF’s though.
For this machine no NOx emissions data is available. The NOx sensor
frequently broadcasted NOx ready = 0 but this was probably caused by the
rapid change of the NOx or O2 value which the sensor could not follow (too slow
response time). The sensor broadcasted NOx values in a normal range,
however the sensor showed intermittently high and fixed oxygen concentration
values of 20.8% when the engine was running under load.

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After the measurement system was uninstalled the sensor was checked with
calibration gases. The sensor responded to changes in calibration gas
concentrations but showed off sets in different directions, i.e. when the
concentration of calibration gas was increased, mostly the sensor value also
increased but at some occasions also decreased in response to an increased
concentration of the calibrations gas. This means that the sensor is broken and
that the logged sensor data can’t be used for calculating the NOx emissions.
The activity data that was recorded shows a low average engine power of
10.9%. Although the average power is low, the post SCR temperature
measured for this machine indicates that for of the most operation the SCR
was at working temperature, roughly above 200 ⁰C.
TNO test code

LI_A9

Brand, type

Liebherr, A914

Configuration

Wheeled excavator

Weight [t]

14,9-16,2t

Engine power [kW], speed [min-1]

105 @1500

Emission Stage

IV (R)

Emission abatement system

SCR

Fuel

EN590 diesel

Running hours

731

Total test period [days], days active [days]

151, 51

Total activity [hours], [hours/day]

272, 5.3

Average power [%]

10.9

Stand-by [minutes/hour]

16

NOx [g/h], [g/kWh]

Not available due to sensor failure.

Total NOx [kg]

Not available due to sensor failure.

CO2 [kg/h]

22

Total CO2 [t]

5.9

Fuel consumption [l/h]

8.2

Average ammonia slip [ppm]

1

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Figure 4: Exhaust gas temperature post SCR. This temperature indicates the working
temperature of the SCR which should roughly be above 200 ⁰C to be able to
efficiently reduce NOx emissions of a diesel engine.

3.4

Stage IV wheel loader
The engine is a Stage IV (R) using EGR and SCR to reduce the NOx emissions
of the diesel engine and as opposed to the Liebherr uses a diesel particle filter
to reduce the particulate emissions. 211 hours of data were collected over 28
active days of the machine. About a quarter of the time the machine is in standby mode with the engine running, performing no or hardly any work. The post
SCR temperatures are mostly above 200 ⁰C, but still there is a share of the
time with lower temperatures, caused by the idling or stand-by mode of the
engine running at very low load. This probably explains a large part of the
higher NOx emissions which on average in real-world operation for this
machine are about twice the Stage V limit value.

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TNO test code

VO_L7

Brand, type

Volvo, L70H

Configuration

Wheel loader

Weight [t]

15.5

Engine power [kW]

127

Emission Stage

IV (R)

Emission abatement system

EGR, SCR, DPF

Fuel

EN590 diesel

Running hours

3635

Total test period [days], days active [days]

41, 28

Total activity [hours], [hours/day]

211, 7.5

Average power [%]

35

Stand-by [minutes/hour]

16

NOx [g/h], [g/kWh]

38, 0.8

Total NOx [kg]

7.9

CO2 [kg/h]

44

Total CO2 [t]

9.3

Fuel consumption [l/h]

16.6

Average ammonia slip [ppm]

6

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Figure 5: Exhaust gas temperature post SCR. This temperature indicates the working
temperature of the SCR which should roughly be above 200 ⁰C to be able to
efficiently reduce NOx emissions of a diesel engine.

3.5

Stage V wheel loader
The engine is a Stage V (NRE v/c 6) using SCR to reduce the NOx emissions
of the diesel engine and uses a diesel particle filter to reduce the particulate
emissions. 468 hours of data were collected over 62 active days of the
machine. On average the daily activity was 7.5 hours with 4 days were the
machine ran almost continuously for 24 hours. About a quarter of the time the
machine is in stand-by mode with the engine running, performing no or hardly
any work. The post SCR temperatures are mostly above 200 ⁰C, but still there
is a share of the time with lower temperatures, caused by the idling or stand-by
mode of the engine running at very low load. This probably explains a large
part of the higher NOx emissions which on average in real-world operation for
this machine are about 1.5 times the Stage V limit value.

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TNO test code

CA_95

Brand, type

Caterpillar, 950M

Configuration

Wheel loader

Weight [t]

19.2

Engine power [kW], speed [min-1]

171

Emission Stage

V (NRE v/c 6)

Emission abatement system

SCR, DPF

Fuel

EN590

Running hours

405 (1766km)

Total test period [days], days active [days]

144, 62

Total activity [hours], [hours/day]

468, 7.5

Average power [%]

35

Stand-by [minutes/hour]

17

NOx [g/h], [g/kWh]

35, 0.6

Total NOx [kg]

16.2

CO2 [kg/h]

56

Total CO2 [t]

26.4

Fuel consumption [l/h]

21.3

Average ammonia slip [ppm]

4

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Figure 6: Exhaust gas temperature post SCR. This temperature indicates the working
temperature of the SCR which should roughly be above 200 ⁰C to be able to
efficiently reduce NOx emissions of a diesel engine.

3.6

Stage V Excavator
In the measurement period of 38 days this machine was only used for 3 hours.
This means that few data are available and the data thus only represents this
limited use of the machine. The data contains a relatively high share of cold
engine operation and idling of the engine which both explains the very high
brake specific NOx emissions (the engine produces hardly any work while
running).

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TNO test code

VO_EC

Brand, type

Volvo EC250

Configuration

Excavator

Weight [t]

27

Engine power [kW], speed [min-1]

159 kW, 1800

Emission Stage

V (NRE v/c 6)

Emission abatement system

SCR, DPF

Fuel

EN590 diesel

Running hours

1244

Total test period [days], days active [days]

38, 3 (few data)

Total activity [hours], [hours/day]

2.9, 1

Average power [%]

3

Stand-by [minutes/hour]

48

NOx [g/h], [g/kWh]

115, 24

Total NOx [kg]

0.3

CO2 [kg/h]

14

Total CO2 [t]

0.04

Fuel consumption [l/h]

5.1

Average ammonia slip [ppm]

3

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Figure 7: Exhaust gas temperature post SCR. This temperature indicates the working
temperature of the SCR which should roughly be above 200 ⁰C to be able to
efficiently reduce NOx emissions of a diesel engine. The short test period and the
large share of cold engine operation in this period resulted in exhaust temperatures
below 200 ⁰C and high brake-specific NOx emissions.

3.7

Particle number emissions
A particle number test was conducted on the machines equipped with a DPF.
With a warm engine and when idling a well-functioning DPF of a passenger car
has a PN emission below 5.000 #/cm3 (Kadijk, 2020). With a cold engine PN
concentrations can be higher, up to 250.000 #/cm3. For the future periodic
inspection test of passenger cars with a DPF the PN concentration of
250.000 #/cm3 is proposed as a limit value (Kadijk, 2020). The results with
PN concentrations at idling around 5000 to 10000 #/cm3 indicate that the tested
machines have properly functioning diesel particle filters. The PN measurement
equipment is meant for engines with DPF. For three machines no
measurements were done because the PN concentrations are very high and
foul the measurement instrument in a few minutes. These three machines have
no diesel particle filter (DPF). For one machine the measurement was aborted
because of an error of the instrument.

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Figure 8: Particle number concentrations: ambient concentrations and concentrations
measured at the tail pipe. For three machines no measurements were done
because the PN concentrations are very high and foul the measurement instrument
in a few minutes. These three machines have no diesel particle filter (DPF). For one
machine the measurement was aborted because of an error of the instrument.

3.8

Overview long term measurements mobile machinery
Results of long term in-use NOx emissions measurements as discussed in this
report can be presented together with the same kind of measurements
conducted on a number of construction equipment conducted in the framework
of Connekt (Ligterink, Louman, Buskermolen, & Verbeek, 2018).
The NOx emissions (Figure 9 and Table 3) show that Stage IV (3) and V (1)
machines with an engine power >= 56 kW are clearly cleaner than the Stage
IIIB machines (2). Expressed in g/kWh, the Stage V mini-excavator and the
trailer cooling unit emit the most, around 9-10 g/kWh. For the Stage V miniexcavator this is caused by the fact that for Stage V only a very loose limit is
applicable for NOx (7.5 g/kWh). For the Stage II cooling unit the Stage II limit
applies which is 8 g/kWh. The high brake specific NOx emissions of the mini
excavator and the cooling unit lead to absolute emissions that are about as
high in g/h as the NOx emissions of the large stage IV and V machines.

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Figure 9: Overview of the long term NOx measurements conducted in the framework of the
2020 emissions testing programme reported in this report (orange) and the
measurements conducted in the framework of Connekt [Ligterink et al., 2018]
(blue).
Table 3: Overview of the NOx and CO2 emissions, fuel consumption and activity of the
mobile machinery measured in the Netherlands (this report and
(Ligterink, Louman, Buskermolen, & Verbeek, 2018)).
Fuel
consumption
[l/h]

Test
duration
[h]

Activity1

[kg/h]

Total
CO2
[t]

[h/day]

Standby2
[min/h]

5.9

10.6

2.2

1787

10.9

6

43.4

53

15.4

20.0

291

7.1

11

48.5

18

6.2

6.8

344

7.0

34

3.1

30

1.3

11.3

44

5.6

15

4.5

42

5.5

15.9

131

6.3

21

0.8

7.9

44

9.3

16.6

211

7.5

16

Max.
power
[kW]

NOX

NOX
[g/kWh]

Total
NOX
[kg]

[g/h]

Trailer cooling unit Stage II

25.3

52

9.5

92.3

Excavator Stage IIIB

159

Wheel loader Stage IIIB

129

149

2.8

141

4.9

Tractor Stage IV

114

Excavator Stage IV

129

70

1.8

34

0.5

Wheel loader Stage IV

CO2

127

38

Wheeled excavator IV

105

n.a.

n.a.

n.a.

22

5.9

8.2

272

5.3

16

Mini excavator Stage V

18.5

36

10.2

0.3

5.8

0.05

2.2

8.3

4

20

Wheel loader Stage V

171

35

0.6

16.2

56

26.4

21.3

468

7.5

17

Excavator Stage V (few data)

159

115

23.5

0.3

14

0.04

5.1

3

1

48

1

Time when the engine is running.

2

Stand-by is defined as the situation were the engine is running but the machine is not moving nor
performing it’s duty. During stand-by the engine may put out some power to propel electric
machines, pumps and compressors.

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Impact of ‘stand-by mode’ on NOx emissions.
The tested machines were in stand-by mode for substantial times of around
35%. The machine that only ran for 3 hours during the entire testing
programme is excluded here. NOx is emitted when the machine is in stand-by
mode and produces no effective work. In principle NOx emissions can be
prevented by shutting off the engine, but for practical reasons often it is not
feasible to shut of the engine immediately.
The data was analysed to determine the share of the NOx emissions produced
during stand-by mode compared to the total NOx emissions. This was done for
different durations of stand-by times, see Figure 10. This shows that the
contribution of NOx emission during standby is extremely high. For the first
three machines, this is 26% to 42% of the total NOx if all standby is included.
For the fourth machine, the Volvo Stage V mini excavator, this was even 60%,
but this machine had only three running hours and is excluded from the main
conclusions.
Many machines are equipped with an automatic idle shut off. This reduces fuel
consumption and also NOx emissions. The idle shut-off usually shuts off the
engine after several minutes. For that reasons also the NOx emissions are
calculated for the idle periods longer than 1 minute, 2 minutes, etc. This shows
how much the NOx emissions can be reduced if the automatic idle shut is used
and is adjusted to that value.
For the first three machines, 1 to 7% of the NOx emissions is caused by standby, lasting more than half an hour. This is 10 to 20% for stand-by times lasting
more than 10 minutes. For stand-by times lasting more than 2 minutes the
NOx emissions of this stand-by are about are about 22 to 33% of the total NOx
emissions. These values are without the Volvo Stage V excavator for which
little data was collected. This showed even higher contributions of standby.

Figure 10: NOx emissions during stand-by mode when no work is produced, for different
duration of the stand-by events. For instance for the CA_95 stand-by events that
last longer than 2 minutes contribute 33% to the total NOx emissions.

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Table 4: Contribution of NOx during standby to total NOx for the first three machines of
Figure 10.

Share of total NOx emitted during standby

3.10

All standby

26 – 42%

Only standby > 60 s
Only standby > 2 minutes

24 – 36%
22 – 33%

Only standby > 3 minutes

20 – 31%

Only standby > 5 minutes
Only standby > 10 minutes

14 – 28%
9 – 21%

Only standby > 30 minutes

1 – 7%

Generating sets and pumps
Mobile machinery mostly use diesel engines. Diesel engines are also used in
stationary machines, for instance for local power generation. These engines
often do not have any emission reduction system and therefore may emit high
levels of NOx and PM. In the past decades, a lot of attention was given to
measuring the emissions of road traffic but little is known about the emissions
level and the activity of the stationary diesel engines such as often used at
construction sites. For these engines, the EU emissions standards were
phased in later than for the engines of mobile machinery. Stage II was the first
standard that applied to constant speed engines in 2007. Stage IIIA was
phased in to constant speed engines starting in 2011.
A measurement programme was conducted using a portable gas analyser
(Testo 350) to measure the concentrations of the gases NO, NO2, NOx, CO,
HC, CO2 and O2 at the exhaust stack of the machinery. A gravimetric method
with a filter and a constant dilution system was used to collect the particulate
matter from the exhaust stack.
Two ‘construction sites’ were selected. The two sites are drilling sites.
The stationary engines that are present at the sites are used for providing the
power for the drills, pumps, local electricity and light. The pumps are for
sewage and supply of high pressure pumping capacity for the drilling activity.
The measurements were spot measurements, which means that samples
are taken of the exhaust gas as is, i.e. during the operation of the machine as
available at the moment of test. In two cases more samples were taken.
For the high pressure pump, measurements were done at high and low load
because the machine was intermittently switching between two load settings.
This machine had a retrofit SCR NOx reduction system attached to the stack.
The SCR uses Selective Catalytic Reduction and reagent (Adblue) to reduce
the NOx emissions of the Caterpillar diesel engine. Measurements were
repeated with SCR active (Adblue dosing on) and inactive (Adblue dosing off).
A light pole was tested with different settings, i.e. all of the four lights on and
all lights off.

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Table 5: Specifications of the machinery tested at the construction site.
Use

High pressure pump

Engine

EU

Emission

Max.

Life time

Life

Life time

Stage

reduction

engine

running

time

avg. power

system

power

hours

work

[kW, %]

[kW]

[h]

[kWh]

340

n.a.

n.a.

n.a.

CAT C15

IIIA

Retrofit SCR

Genset

MAN D2862LE221

II

-

770

9548

674592

70.1 , 8

Sewage Pump

Hatz 4M41

IIIA

-

33

856

n.a.

n.a.

Light pole

Kubota

II

-

2.3

3413

n.a.

n.a.

Genset

John Deere 4045HFU8112V

IIIA

-

48

6970

59181

8.5 , 18

Genset

Hatz

II

-

41

1864

n.a.

n.a.

Genset

n.a.

II

-

19

n.a.

n.a.

n.a.

Drilling rig

CAT 7.1

V

SCR, DPF

205

n.a.

n.a.

n.a.

The NOx emission results are presented in figure 13 and also in table 6 below.
The results of the NOx measurements show variations. The high pressure
pump with SCR with Adblue dosing switched on, and the Stage V drill, also
equipped with SCR, show very low NOx emissions of a few g/h. The retrofit
SCR system of the high pressure pump reduces NOx emissions of the
Caterpillar diesel engine with about 98% efficiency at the given engine load
points. The other light machines show NOx emissions in the order of 50 to
140 g/h. This is in the same range as the Stage IIIB to V mobile machines
summarised in table 3. It also shows that the very small machines with
12-19 kW engine power have about the same NOx emissions in g/h as the
much larger stationairy and mobile machines with 40 to 170 kW power.
The large genset with a 770 kW engine shows by far the highest NOx
emissions of 4.1 kg/h at the medium load (46%) the machine was running at.
This is comparable to about 100 (!) mobile machines such as medium size
excavators and side loaders with a Stage IV or V engine. This high emissions
level is caused by the high power but also by the high brake specific
NOx emissions of this engine, which is 11.7 g/kWh at the measured load point.
The engine for this genset is provided as a ‘low fuel’ and as a ‘low NOx’ variant.
The low fuel configuration would mean a NOx concenration lower than 4000
mg/m3 (< about 2000 ppm) according TA luft 2002 requirements. The low
NOx configuration would comply with the old Stage II limit which is 6 g/kWh.
With a measured NOx concentration of 1462 ppm this engine probably is a
‘fuel optimized’ variant. The generator set tested is build in 2013 but has a
power rating of 770 kW and due to the high power rating falls outside the scope
of the NRMM regulation. Widening of the scope to engines above 560 kW (and
below 19 kW) only happens at Stage V (2021). For engines for gensets
separate limits were introduced at Stage V (category NRG) of 0.67 g/kWh,
0.035 g/kWh for PM and no limit for PN. The level of the PM limit and the
absence of a PN limit means that for large genset engines no DPF would be
required to meet Stage V requirements.
The NO2 emissions of the engines without emission abatement system vary
from a few to 50% of the total NOx emissions (refer to Table 6). The highest
fractions of NO2 are emitted by the engine with a retrofit SCR system, but for
this machine the absolute levels of NOx and thus also NO2 are very low.

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Figure 11: Spot measurements of the NOx emissions of stationary machines at the
construction site in g/h and g/kWh. The high pressure pump was measured at low
and high load and with and without SCR Reagent dosing (Adblue) dosing active.
The light pole was tested with all lights on and off.

The particulate matter mass emissions, PM, are presented in Figure 12 and
Figure 13, and are also presented in Table 6, which also gives an overview of
all emission components. The PM emissions also show variations. Also here
the largest engine with the high power rating of 770 kW has the highest
emissions. It’s brake specific PM emission expressed in g/kWh is rather low
however. The small 19 kW genset has brake specific PM emissions of about
0.5 g/kWh.

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Figure 12: Spot measurements of the PM mass emissions of stationary machines at the
construction site in g/h and g/kWh. The high pressure pump was measured at low
and high load.

Figure 13: Spot measurements of the PM mass emissions of stationary machines at the
construction site in g/h showing duplicate and triplicate repetitions of the PM
measurement. The repetitions show the variation for PM measurement in the
field. The maximum difference between two duplicates was 19%.

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Table 6: Emissions results of the machinery tested at the construction site.

kW

Approx1.
Load, %
of Pmax
[%]

[g/h]

[g/h]

[g/h]

[g/h]

[kg/h]

[g/h]

[g/h]

HP pump 340kW load

340

21%

463

7

470

88

49

6

5.2

HP pump 340kW idle

340

2%

87

12

98

0

6

3

HP pump 340 kW SCR load

340

21%

5

4

8

10

47

6

Pmax

NO

NO2

NOx

CO

CO2

HC

PM

0.9
n.a.

HP pump 340 kW SCR idle

340

2%

1.6

1.1

3

4

6

3

n.a.

Genset 770kW

770

46%

4012

130

4143

1425

227

8

14.0

Sewage Pump 33kW

33

35%

52

17

69

174

8

2

4.2

Lightpole 12 kW

12

99%

74

6

80

26

9

1

1

Lightpole 12kW lights off

12

17%

38

10

49

70

4

1

n.a.

Genset 48kW

48

23%

98

5

103

187

23

2

7.3

Drill 205 kW Stage V

205

24%

7

0.4

8

2

34

3

2.0

Genset 41kW

41

66%

138

2

140

92

19

0.0

n.a.

Genset 19kW

19

39%

45

5

50

35

5

1

3.8

1

As available on the engine display, estimated from the applied electrical load or from fuel
consumption calculated from engine speed and lambda (from O2 concentration) for non-turbo
engines.

TNO report | TNO 2021 R10221 | 11 February 2021

4

34 / 37

Conclusions
TNO has carried out an emissions measurement program to determine the
real-world emissions of a selection of mobile machines with 2 excavators, a
mini excavator, 2 wheel loaders, a transport cooling unit and stationary
machinery such as pumps and generator sets. From results of the tested
machinery the following can be concluded:
The measured large Stage IV (3) and V (1) mobile machines (power >= 56
kW), all equipped with SCR, emit 0.5 to 0.8 g/kWh NOx which is cleaner than
the measured Stage IIIB machines (2) which emit 2.8 to 4.9 g/kWh. All
machines were tested in real-world operation.
The Stage IV and V machines still emit more than the Stage IV and V limit of
0.4 g/kWh which accounts for the formal engine test of the type approval
procedure.
The machines operate a lot in stand-by mode, about 35% of the total running
time. This means that the engine is running but no work is produced. NOx
emissions during stand-by mode represent 26 to 42% share of the total NOx
emissions. For instance, when the engine would be stopped after two minutes,
by adaptation of the driver's behavior (turning off the engine) or using a
start-stop system, 22 to 33% of NOx emission would be avoided.
The ammonia slip of the Stage IV and V machines equipped with SCR was
generally low in real-world operation, with average ammonia concentrations
in the exhaust of 1 to 8 ppm. On an official motor test for Stage V, the average
ammonia concentration should not exceed 10 ppm.
Small mobile machines (power < 56 kW) are very dirty. A refrigerated trailer
unit (driven by a small diesel engine) emits on average 52 g/h NOx, which is
1.5 times as much for NOx and more than 10 times as much for particulate
matter than the Euro-VI trucks that drives in front of it.
The tested 2.5 t mini-excavator emits 36 g/h on average, which is about the
same level as a large Stage IV excavator and a large Stage V wheel loader.
The reason of the high NOx emissions is that non-stringent emission
requirements apply to small mobile machines, even for Stage V engines with
a power lower than 56 kW.
Most of the measured stationary machines (pumps and generator sets) are
very dirty. The reason is that these machines had to comply with old and nonstringent very flexible emissions standards. In case of low powered (<19 kW) or
high powered engines (>560 kW), even no emission limit applied. Many small
dirty sources that run for many hours together can emit a lot. But also a single
large machine can emit a lot on its own. A large generator with a 770 kW
engine, out of the scope of the EU emissions regulation, had NOx emissions of
4.1 kg/h during operation and in this case emits about as much NOx as 100
large mobile machines or 100 Euro VI trucks.

TNO report | TNO 2021 R10221 | 11 February 2021

35 / 37

A pump with a dirty diesel engine, fitted by the owner with an emission
reduction system for NOx, shows very low NOx emissions, lower than the level
of the Stage V standard. A Stage V engine equipped with SCR, as used on a
drilling rig, is very clean as well. This indicates that the Stage V limit for
stationary engines and the emissions abatement technology SCR can be very
effective.
In this study, measurements were carried out on a limited number of mobile
machinery and stationary sources on a construction site. This provides a first
indication of the level of real-world NOx and particulate matter emissions of
these sources. More measurements are needed to obtain a complete and
reliable picture of the emissions of the very broad NRMM and stationary engine
categories.
Acknowledgements
Acknowledgments go to all companies which provided their machinery for the
emission tests.

TNO report | TNO 2021 R10221 | 11 February 2021

5

36 / 37

References
Desouza, C., Marsh, D., Beevers, S., Molden, N., & Green, D. (2020). Realworld emissions from non-road mobile machinery in London.
(Atmospheric Environment 223 (2020) 117301). Elsevier.
Kadijk, G. (2020, January 13). Follow-up research into the PN limit value and
the measurement method for checking particulate filters with a particle
number counter.
Ligterink, N., Louman, R., Buskermolen, E., & Verbeek, R. (2018, October).
Connekt Topsector logistiek, Use of construction machines and
associated NOx and CO2 emissions.
Sandström Dahl, C., & Willner, C. (2015). Test report OMT 4005, on-board
emissions measurement on wheel loaders with different emissions
standards.
Sandström Dahl, C., & Willner, C. (2016). Test report OMT 5005, on-board
emissions measurement on wheel loader in different test cycles.
van den Meiracker, J., & Vermeulen, R. (2020, March 31). The market of
cheating devices and testing matrix with a prioritization for testing of
vehicle tampering technique combinations.
Wisell, T., Jerksjö, M., Hult, C., & Lindgren, M. (2018, April). Fuel and
Technology Alternatives in Non-Road Engines. A report from the IEA
Advanced Motor Fuels Technology Collaboration Programme: Annex
50.

TNO report | TNO 2021 R10221 | 11 February 2021

6

37 / 37

Signature
The Hague, 11 February 2021

TNO

P.J. van der Mark
Projectleader

R.J. Vermeulen
Author

TNO report | TNO 2021 R10221 | 11 February 2021

A

Appendix A | 1/3

Overview of EU Stage norms
Source: https://dieselnet.com, December 2020.

Stage V2

Stage V2

Stage IV

Stage IIIB

Stage IIIB

Stage IIIB

Stage IIIA

Stage IIIA

Stage IIIA

Stage II

Stage II

Stage II

Net
power
[kW]

199
9
200
0
200
1
200
2
200
3
200
4
200
5
200
6
200
7
200
8
200
9
201
0
201
1
201
2
201
3
201
4
201
5
201
6
201
7
201
8
201
9
202
202
020
22

Stage I

Stage II

Table 7: NOx and in some cases HC+NOx emission standards for non-road diesel engines.

0-8

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

7.51

8-19

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

7.51

19-37

-

-

37-75

7.51

8

9.2

4.71
1

7

4.7

37-56
56-75

3.3

75-130

9.2

56-130
130560
>560

4.71

4.7

6

4

1

3.3
9.2
-

6
-

-

-

4
-

-

-

-

1

0.4

2
-

-

-

-

-

0.4

0.4
-

-

-

0.4
-

-

-

-

3.5

Stage II for CS engines effective 2007.01, Stage IIIA 2011.01 (19-37 and 75-130) and 2012.01 (37-75)
1

combined HC+NOx limit

2

Transitional provision and exception with a period of 24 months. Production within 18 months after effective date and put on market

within 6 month later. Category 5 are exempt: effective date is January 1st 2020 followed by the 24 month period.
Due to Covid-19 pandemic in July 2020 the effective date was extended from 2020 to 31-12-2021 for engines < 56 kW and
>130kW, the same effective date as for engines 56 to 130kW which wasn’t changed.

Ammonia limit as of Stage III 25ppm over test cycle, for Stage V this is 10 ppm with
exception of category RRL.

TNO report | TNO 2021 R10221 | 11 February 2021

Cat.

Net Power

Date*

Appendix A | 2/3

CO

HC

kW

NOx

PM

g/kWh

Stage I
A

130 ≤ P ≤
560
75 ≤ P <
130
37 ≤ P <
75

B
C

1999.01

5

1.3

9.2

0.54

1999.01

5

1.3

9.2

0.7

1999.04

6.5

1.3

9.2

0.85

6

0.2

6

0.3

7

0.4

8

0.8

HC+NOx

NOx

PM

Stage II
E

130 ≤ P ≤
2002.01
3.5
1
560
F
75 ≤ P <
2003.01
5
1
130
G
37 ≤ P <
2004.01
5
1.3
75
D
18 ≤ P <
2001.01
5.5
1.5
37
* Stage II also applies to constant speed engines effective 2007.01

Stage III A/B emission standards for nonroad diesel engines
Cat.

Net Power

Date†

CO

HC

kW

g/kWh

Stage III A
H

130 ≤ P ≤ 560

2006.01

3.5

-

4

-

0.2

I

75 ≤ P < 130

2007.01

5

-

4

-

0.3

J

37 ≤ P < 75

2008.01

5

-

4.7

-

0.4

K

19 ≤ P < 37

2007.01

5.5

-

7.5

-

0.6

L

130 ≤ P ≤ 560

2011.01

3.5

0.19

-

2

0.025

M

75 ≤ P < 130

2012.01

5

0.19

-

3.3

0.025

N

56 ≤ P < 75

2012.01

5

0.19

-

3.3

0.025

P

37 ≤ P < 56

2013.01

5

-

4.7

-

0.025

Stage III B

† Dates for constant speed engines are: 2011.01 for categories H, I and K; 2012.01 for category J.

Stage IV emission standards for nonroad diesel engines
t.

Net Power

Date

CO

HC

kW

NOx

PM

g/kWh

Q

130 ≤ P ≤ 560

2014.01

3.5

0.19

0.4

0.025

R

56 ≤ P < 130

2014.1

5

0.19

0.4

0.025

TNO report | TNO 2021 R10221 | 11 February 2021

Appendix A | 3/3

Stage V emission limits for engines in nonroad mobile machinery (category NRE).
Cat.

Ign.

Net Power

NRE-v/c-1

CI

P<8

Date1

CO

2019

8

7.50a,c

6.6

HC

NOx

kW

NRE-v/c-2

CI

8 ≤ P < 19

PM

1/kWh

g/kWh

2019

NRE-v/c-3

CI

19 ≤ P < 37

2019

5

NRE-v/c-4

CI

37 ≤ P < 56

2019

5

PN

0.40b

-

7.50

a,c

0.4

-

4.70

a,c

0.015

1×1012

4.70a,c

0.015

1×1012

c

0.4

0.015

1×1012

NRE-v/c-5

All

56 ≤ P < 130

2020

5

0.19

NRE-v/c-6

All

130 ≤ P ≤ 560

2019

3.5

0.19c

0.4

0.015

1×1012

NRE-v/c-7

All

P > 560

2019

3.5

0.19d

3.5

0.045

-

a

HC+NOx

b

0.60 for hand-startable, air-cooled direct injection engines
1

Transitional provision and exception with a period of 24 months. Production within 18 months after
effective date and put on market within 6 month later. Category 5 are exempt: effective date is
January 1st 2020 followed by the 24 month period.

Engines above 560 kW used in generator sets (category NRG) must meet
standards shown in Table 5 (NRSC and NRTC test cycles).
Category

Ign.

Net. Power

Date

CO

HC

NOx

kW
NRG-v/c-1
a

All

A = 6.00 for gas engines

P > 560

PM

g/kWh
2019

3.50

a

0.19

PN

1/kWh
0.67

0.035

-