Nitrogen Oxides, 1988 in United States

Nitrogen Oxides, 1988

PROTOCOL TO THE 1979
CONVENTION ON LONG-RANGE TRANSBOUNDARY AIR POLLUTION
CONCERNING THE CONTROL OF EMISSIONS OF NITROGEN OXIDES
OR THEIR TRANSBOUNDARY FLUXES (1988)

ENTERED INTO FORCE: 2 February 1991

The Parties,

Determined to implement the Convention on Long-range Transboundary Air
Pollution,

Concerned that present emissions of air pollutants are causing damage, in
exposed parts of Europe and North America, to natural resources of vital
environmental and economic importance,

Recalling that the Executive Body for the Convention recognized at its
second session the need to reduce effectively the total annual emissions
of nitrogen oxides from stationary and mobile sources or their
transboundary fluxes by 1995, and the need on the part of other States
that had already made progress in reducing these emissions to maintain
and review their emission standards for nitrogen oxides,

Taking into consideration existing scientific and technical data on
emissions, atmospheric movements and effects on the environment of
nitrogen oxides and their secondary products, as well as on control
technologies,

Conscious that the adverse environmental effects of emissions of nitrogen
oxides vary among countries,

Determined to take effective action to control and reduce national annual
emissions of nitrogen oxides or their transboundary fluxes by, in
particular, the application of appropriate national emission standards to
new mobile and major new stationary sources and the retrofitting of
existing major stationary sources,

Recognizing that scientific and technical knowledge of these matters is
developing and that it will be necessary to take such developments into
account when reviewing the operation of this Protocol and deciding on
further action,

Noting that the elaboration of an approach based on critical loads is
aimed at the establishment of an effect-oriented scientific basis to be
taken into account when reviewing the operation of this Protocol and at
deciding on further internationally agreed measures to limit and reduce
emissions of nitrogen oxides or their transboundary fluxes,

Recognizing that the expeditious consideration of procedures to create
more favourable conditions for exchange of technology will contribute to
the effective reduction of emissions of nitrogen oxides in the region of
the Commission,

Noting with appreciation the mutual commitment undertaken by several
countries to implement immediate and substantial reductions of national
annual emissions of nitrogen oxides, Acknowledging the measures already
taken by some countries which have had the effect of reducing emissions
of nitrogen oxides, Have agreed as follows:

Article 1

Definitions

For the purposes of the present Protocol,

1. “Convention” means the Convention on Long-range Transboundary Air
Pollution, adopted in Geneva on 13 November 1979;

2. “EMEP” means the Cooperative Programme for Monitoring and Evaluation
of the Long-range Transmission of Air Pollutants in Europe;

3. “Executive Body” means the Executive Body for the Convention
constituted under article 10, paragraph 1 of the Convention;

4. “Geographical scope of EMEP” means the area defined in article 1,
paragraph 4 of the Protocol to the 1979 Convention on Long-range
Transboundary Air Pollution on Long-term Financing of the Cooperative
Programme for Monitoring and Evaluation of the Long-range Transmission of
Air Pollutants in Europe (EMEP), adopted in Geneva on 28 September 1984;

5. “Parties” means, unless the context otherwise requires, the Parties to
the present Protocol;

6. “Commission” means the United Nations Economic Commission for Europe;

7. “Critical load” means a quantitative estimate of the exposure to one
or more pollutants below which significant harmful effects on specified
sensitive elements of the environment do not occur according to present
knowledge;

8. “Major existing stationary source” means any existing stationary
source the thermal input of which is at least 100 MW;

9. “Major new stationary source” means any new stationary source the
thermal input of which is at least 50 MW;

10. “Major source category” means any category of sources which emit or
may emit air pollutants in the form of nitrogen oxides, including the
categories described in the Technical Annex, and which contribute at
least 10 per cent of the total national emissions of nitrogen oxides on
an annual basis as measured or calculated in the first calendar year
after the date of entry into force of the present Protocol, and every
fourth year thereafter;

11. “New stationary source” means any stationary source the construction
or substantial modification of which is commenced after the expiration of
two years from the date of entry into force of this Protocol;

12. “New mobile source” means a motor vehicle or other mobile source
which is manufactured after the expiration of two years from the date of
entry into force of the present Protocol.

Article 2

Basic obligations

1. The Parties shall, as soon as possible and as a first step, take
effective measures to control and/or reduce their national annual
emissions of nitrogen oxides or their transboundary fluxes so that these,
at the latest by 31 December 1994, do not exceed their national annual
emissions of nitrogen oxides or transboundary fluxes of such emissions
for the calendar year 1987 or any previous year to be specified upon
signature of, or accession to, the Protocol, provided that in addition,
with respect to any Party specifying such a previous year, its national
average annual transboundary fluxes or national average annual emissions
of nitrogen oxides for the period from 1 January 1987 to 1 January 1996
do not exceed its transboundary fluxes or national emissions for the
calendar year 1987.

2. Furthermore, the Parties shall in particular, and no later than two
years after the date of entry into force of the present Protocol:

(a) Apply national emission standards to major new stationary sources
and/or source categories, and to substantially modified stationary
sources in major source categories, based on the best available
technologies which are economically feasible, taking into consideration
the Technical Annex;

(b) Apply national emission standards to new mobile sources in all
major source categories based on the best available technologies which
are economically feasible, taking into consideration the Technical Annex
and the relevant decisions taken within the framework of the Inland
Transport Committee of the Commission; and

(c) Introduce pollution control measures for major existing stationary
sources, taking into consideration the Technical Annex and the
characteristics of the plant, its age and its rate of utilization and the
need to avoid undue operational disruption.

3. (a) The Parties shall, as a second step, commence negotiations, no
later than six months after the date of entry into force of the present
Protocol, on further steps to reduce national annual emissions of
nitrogen oxides or transboundary fluxes of such emissions, taking into
account the best available scientific and technological developments,
internationally accepted critical loads and other elements resulting from
the work programme undertaken under article 6.

(b) To this end, the Parties shall co-operate in order to establish:

(i) Critical loads;

(ii) Reductions in national annual emissions of nitrogen oxides or
transboundary fluxes of such emissions as required to achieve
agreed objectives based on critical loads; and

(iii) Measures and a time-table commencing no later than 1 January
1996 for achieving such reductions.

4. Parties may take more stringent measures than those required by the
present article.

Article 3

Exchange of technology

1. The Parties shall, consistent with their national laws, regulations
and practices, facilitate the exchange of technology to reduce emissions
of nitrogen oxides, particularly through the promotion of:

(a) Commercial exchange of available technology;

(b) Direct industrial contacts and cooperation, including joint
ventures;

(c) Exchange of information and experience; and

(d) Provision of technical assistance.

2. In promoting the activities specified in subparagraphs (a) to (d)
above, the Parties shall create favourable conditions by facilitating
contacts and cooperation among appropriate organizations and individuals
in the private and public sectors that are capable of providing
technology, design and engineering services, equipment or finance.

3. The Parties shall, no later than six months after the date of entry
into force of the present Protocol, commence consideration of procedures
to create more favourable conditions for the exchange of technology to
reduce emissions of nitrogen oxides.

Article 4

Unleaded fuel

The Parties shall, as soon as possible and no later than two years after
the date of entry into force of the present Protocol, make unleaded fuel
sufficiently available, in particular cases as a minimum along main
international transit routes, to facilitate the circulation of vehicles
equipped with catalytic converters.

Article 5

Review process

1. The Parties shall regularly review the present Protocol, taking into
account the best available scientific substantiation and technological
development.

2. The first review shall take place no later than one year after the
date of entry into force of the present Protocol.

Article 6

Work to be undertaken

The Parties shall give high priority to research and monitoring related
to the development and application of an approach based on critical loads
to determine, on a scientific basis, necessary reductions in emissions of
nitrogen oxides. The Parties shall, in particular, through national
research programmes, in the work plan of the Executive Body and through
other cooperative programmes within the framework of the Convention, seek
to:

(a) Identify and quantify effects of emissions of nitrogen oxides on
humans, plant and animal life, waters, soils and materials, taking into
account the impact on these of nitrogen oxides from sources other than
atmospheric deposition;

(b) Determine the geographical distribution of sensitive areas;

(c) Develop measurements and model calculations including harmonized
methodologies for the calculation of emissions, to quantify the
long-range transport of nitrogen oxides and related pollutants;

(d) Improve estimates of the performance and costs of technologies for
control of emissions of nitrogen oxides and record the development of
improved and new technologies; and

(e) Develop, in the context of an approach based on critical loads,
methods to integrate scientific, technical and economic data in order to
determine appropriate control strategies.

Article 7

National programmes, policies and strategies

The Parties shall develop without undue delay national programmes,
policies and strategies to implement the obligations under the present
Protocol that shall serve as a means of controlling and reducing
emissions of nitrogen oxides or their transboundary fluxes.

Article 8

Information exchange and annual reporting

1. The Parties shall exchange information by notifying the Executive Body
of the national programmes, policies and strategies that they develop in
accordance with article 7 and by reporting to it annually on progress
achieved under, and any changes to, those programmes, policies and
strategies, and in particular on:

(a) The levels of national annual emissions of nitrogen oxides and the
basis upon which they have been calculated;

(b) Progress in applying national emission standards required under
article 2, subparagraphs 2(a) and 2(b), and the national emission
standards applied or to be applied, and the sources and/or source
categories concerned;

(c) Progress in introducing the pollution control measures required
under article 2, subparagraph 2(c), the sources concerned and the
measures introduced or to be introduced;

(d) Progress in making unleaded fuel available;

(e) Measures taken to facilitate the exchange of technology; and

(f) Progress in establishing critical loads.

2. Such information shall, as far as possible, be submitted in accordance
with a uniform reporting framework.

Article 9

Calculations

EMEP shall, utilizing appropriate models and in good time before the
annual meetings of the Executive Body, provide to the Executive Body
calculations of nitrogen budgets and also of transboundary fluxes and
deposition of nitrogen oxides within the geographical scope of EMEP. In
areas outside the geographical scope of EMEP, models appropriate to the
particular circumstances of Parties to the Convention therein shall be
used.

Article 10

Technical Annex

The Technical Annex to the present Protocol is recommendatory in
character. It shall form an integral part of the Protocol.

Article 11

Amendments to the Protocol

1. Any Party may propose amendments to the present Protocol.

2. Proposed amendments shall be submitted in writing to the Executive
Secretary of the Commission who shall communicate them to all Parties.
The Executive Body shall discuss the proposed amendments at its next
annual meeting provided that these proposals have been circulated by the
Executive Secretary to the Parties at least ninety days in advance.

3. Amendments to the Protocol, other than amendments to its Technical
Annex, shall be adopted by consensus of the Parties present at a meeting
of the Executive Body, and shall enter into force for the Parties which
have accepted them on the ninetieth day after the date on which
two-thirds of the Parties have deposited their instruments of acceptance
thereof. Amendments shall enter into force for any Party which has
accepted them after two-thirds of the Parties have deposited their
instruments of acceptance of the amendment, on the ninetieth day after
the date on which that Party deposited its instrument of acceptance of
the amendments.

4. Amendments to the Technical Annex shall be adopted by consensus of the
Parties present at a meeting of the Executive Body and shall become
effective thirty days after the date on which they have been communicated
in accordance with paragraph 5 below.

5. Amendments under paragraphs 3 and 4 above shall, as soon as possible
after their adoption, be communicated by the Executive Secretary to all
Parties.

Article 12

Settlement of disputes

If a dispute arises between two or more Parties as to the interpretation
or application of the present Protocol, they shall seek a solution by
negotiation or by any other method of dispute settlement acceptable to
the parties to the dispute.

Article 13

Signature

1. The present Protocol shall be open for signature at Sofia from 1
November 1988 until 4 November 1988 inclusive, then at the Headquarters
of the United Nations in New York until 5 May 1989, by the member States
of the Commission as well as States having consultative status with the
Commission, pursuant to paragraph 8 of Economic and Social Council
resolution 36 (IV) of 28 March 1947, and by regional economic integration
organizations, constituted by sovereign States members of the Commission,
which have competence in respect of the negotiation, conclusion and
application of international agreements in matters covered by the
Protocol, provided that the States and organizations concerned are
Parties to the Convention.

2. In matters within their competence, such regional economic integration
organizations shall, on their own behalf, exercise the rights and fulfil
the responsibilities which the present Protocol attributes to their
member States. In such cases, the member States of these organizations
shall not be entitled to exercise such rights individually.

Article 14

Ratification, acceptance, approval and accession

1. The present Protocol shall be subject to ratification, acceptance or
approval by Signatories.

2. The present Protocol shall be open for accession as from 6 May 1989 by
the States and organizations referred to in article 13, paragraph 1.

3. A State or organization which accedes to the present Protocol after 31
December 1993 may implement articles 2 and 4 no later than 31 December
1995.

4. The instruments of ratification, acceptance, approval or accession
shall be deposited with the Secretary-General of the United Nations, who
will perform the functions of depositary.

Article 15

Entry into force

1. The present Protocol shall enter into force on the ninetieth day
following the date on which the sixteenth instrument of ratification,
acceptance, approval or accession has been deposited.

2. For each State and organization referred to in article 13, paragraph
1, which ratifies, accepts or approves the present Protocol or accedes
thereto after the deposit of the sixteenth instrument of ratification,
acceptance, approval, or accession, the Protocol shall enter into force
on the ninetieth day following the date of deposit by such Party of its
instrument of ratification, acceptance, approval, or accession.

Article 16

Withdrawal

At any time after five years from the date on which the present Protocol
has come into force with respect to a Party, that Party may withdraw from
it by giving written notification to the depositary. Any such withdrawal
shall take effect on the ninetieth day following the date of its receipt
by the depositary, or on such later date as may be specified in the
notification of the withdrawal.

Article 17

Authentic texts

The original of the present Protocol, of which the English, French and
Russian texts are equally authentic, shall be deposited with the
Secretary-General of the United Nations.

In witness whereof the undersigned, being duly authorized thereto, have
signed the present Protocol.

Done at Sofia this thirty-first day of October one thousand nine hundred
and eighty-eight.

TECHNICAL ANNEX

1. Information regarding emission performance and costs is based on
official documentation of the Executive Body and its subsidiary bodies,
in particular documents EB.AIR/WG.3/R.8, R.9 and R.16, and ENV/WP.l/R.86,
and Corr.1, as reproduced in chapter 7 of Effects and Control of
Transboundary Air Pollution.* Unless otherwise indicated, the
technologies listed are considered to be well established on the basis of
operational experience. **

[ * Air Pollution Studies No. 4 (United Nations publication, Sales
No. E.87.II.E.36).
** It is at present difficult to provide reliable data on the
costs of control technologies in absolute-terms. For cost data
included in the present annex, emphasis should therefore be placed
on the relationships between the costs of different technologies
rather than on absolute cost figures. ]

2. The information contained in this annex is incomplete. Because
experience with new engines and new plants incorporating low emission
technology, as well as with retrofitting existing plants, is continuously
expanding, regular elaboration and amendment of the annex will be
necessary. The annex cannot be an exhaustive statement of technical
options; its aim is to provide guidance for the Parties in identifying
economically feasible technologies for giving effect to the obligations
of the Protocol.

I. CONTROL TECHNOLOGIES FOR NOx EMISSIONS FROM STATIONARY SOURCES

3. Fossil fuel combustion is the main stationary source of anthropogenic
NOx emissions. In addition, some non-combustion processes can contribute
relevant NOx emissions.

4. Major stationary source categories of NOx emissions may include:
(a) Combustion plants;
(b) Industrial process furnaces (e.g., cement manufacture);
(c) Stationary gas turbines and internal combustion engines; and
(d) Non-combustion processes (e.g., nitric acid production).

5. Technologies for the reduction of NOx emissions focus on certain
combustion/process modifications, and, especially for large power plants,
on flue gas treatment.

6. For retrofitting of existing plants, the extent of application of
low-NOx technologies may be limited by negative operational side-effects
or by other site-specific constraints. In the case of retrofitting,
therefore, only approximate estimates are given for typically achievable
NOx emission values. For new plants, negative side-effects can be
minimized or excluded by appropriate design features.

7. According to currently available data, the costs of combustion
modifications can be considered as small for new plants. However, in the
case of retrofitting, for instance at large power plants, they ranged
from about 8 to 25 Swiss francs per KWel (in 1985). As a rule,
investment costs of flue gas treatment systems are considerably higher.

8. For stationary sources, emission factors are expressed in milligrams
of NO2 per normal (0 degrees C, 1013 mb) cubic metre (mg/m3), dry basis.

Combustion plants
9. The category of combustion plants comprises fossil fuel combustion in
furnaces, boilers, indirect heaters and other combustion facilities with
a heat input larger than 10 MW, without mixing the combustion flue gases
with other effluents or treated materials. The following combustion
technologies, either singly or in combination, are available for new and
existing installations:

(a) Low-temperature design of the firebox, including fluidized bed
combustion;
(b) Low excess-air operation;
(c) Installation of special low-NOx burners;
(d) Flue gas recirculation into the combustion air;
(e) Staged combustion/overfire-air operation; and
(f) Reburning (fuel staging). ***

[ *** There is limited operational experience of this type of
combustion technology. ]

Performance standards that can be achieved are summarized in table 1.

10. Flue gas treatment by selective catalytic reduction (SCR) is an
additional NOx emission reduction measure with efficiencies of up to 80
per cent and more. Considerable operational experience from new and
retrofitted installations is now being obtained within the region of the
Commission, in particular for power plants larger than 300 MW (thermal).
When combined with combustion modifications, emission values of 200 mg/m3
(solid fuels, 6% 02) and 150 mg/m3 (liquid fuels, 3% 02) can be easily
met.

11. Selective non-catalytic reduction (SNCR), a flue gas treatment for a
20-60% NOx reduction, is a cheaper technology for special applications
(e.g., refinery furnaces and base load gas combustion).

Table 1: NOx performance standards (mg/m3) that can be achieved by combustion
modifications

Plant type a/ Uncontrolled baseline
——————————————————————–
| | Grate Combustion (coal) 300 – 1000
|10 MW c/ | Fluidized Bed Combustion
| to | (i) stationary 300 – 600
|300 MW | (ii) circulating 150 – 300
| | Pulverized Coal Combustion
| | (i) dry bottom 700 – 1700
Solid | | (ii) wet bottom 1000 – 2300
Fuels | |
| | Pulverized Coal Combustion
|> 300 MW | (i) dry bottom 700 – 1700
| | (ii) wet bottom 1000 – 2300
| |
| 10 MW c/ | Distillate Oil Combustion –
| to |
Liquid | 300 MW | Residual Oil Combustion 500 – 1400
Fuels | |
| > 300 MW | Residual Oil Combustion 500 – 1400
| 10 MW c/ |
| to |
Gaseous | 300 MW | 150 – 1000
Fuels | |
| > 300 MW | 250 – 1400

a/ capacity numbers refer to MW (thermal) heat input by fuel (lower heating
value.
c/ For small (10 MW – 100 MW) plants a greater degree of uncertainty
applies to all figures given.

Table 1: NOx performance standards (mg/m3) that can be achieved by combustion
modifications [cont.]

Existing plant retrofit b/ New plant O2
Range Typical value %
—————————————————————————
– 600 400 7
| 10 MW c/ |
| to | – – 400 7
| 300 MW | – – 200 7
| | 600 – 1100 800 < 600 6
Solid | |1000 – 1400 – 300 MW | 600 – 1100 – < 600 6
| |1000 – 1400 – 300MW | 200 – 400 – – 3
| |
| 10 MW c/ |
| to |
Gaseous | 300 MW | 100 – 300 – 300 MW | 100 – 300 – 8 bar) is
capable of keeping NOx concentrations in undiluted effluents below 400 mg/m3.
The same emission performance can be met by medium pressure absorption in
combination with a SCR process or any other similar efficient NOx reduction
process. Retrofit is possible.

II. CONTROL TECHNOLOGIES FOR NOx EMISSIONS FROM MOTOR VEHICLES

16. The motor vehicles considered in this annex are those used for road
transport, namely: petrol-fuelled and diesel-fuelled passenger cars,
light-duty vehicles and heavy-duty vehicles. Appropriate reference is made,
as necessary, to the specific vehicle categories (M1, M2, M3, N1, N2, N3)
defined in ECE Regulation No. 13 pursuant to the 1958 Agreement concerning the
Adoption of Uniform Conditions of Approval and Reciprocal Recognition of
Approval for Motor Vehicles Equipment and Parts.

17. Road transport is a major source of anthropogenic NOx emission in many
Commission countries, contributing between 40 and 80 per cent of total
national emissions. Typically, petrol-fuelled vehicles contribute two-thirds
of total road transport NOx emissions.

18. The technologies available for the control of nitrogen oxides from motor
vehicles are summarized in tables 3 and 6. It is convenient to group the
technologies by reference to existing or proposed national and international
emission standards differing in stringency of control. Because current
regulatory test cycles only reflect urban and metropolitan driving, the
estimates of relative NOx emissions given below take account of higher speed
driving where NOx emissions can be particularly important.

19. The additional production cost figures for the various technologies given
in tables 3 and 6 are manufacturing cost estimates rather than retail prices.

20. Control of production conformity and in-use vehicle performance is
important in ensuring that the reduction potential of emission standards is
achieved in practice.

21. Technologies that incorporate or are based on the use of catalytic
converters require unleaded fuel. Free circulation of vehicles equipped with
catalytic converters depends on the general availability of unleaded petrol.

Petrol-fuelled and diesel-fueled passenger cars (M1)
22. In table 2, four emission standards are summarized. These are used in
table 3 to group the various engine technologies for petrol vehicles according
to their NOx emission reduction potential.

Table 2: Definition of emission standards
————————————————————————–
Standard Limits Comments
————————————————————————–
A. ECE R.15-04 HC + NOx: 19-28 g/test Current ECE standard
(Regulation No.15, including
the 04 series of amendments,
pursuant to the 1958 Agreement
referred to in paragraph 16
above), also adopted by the
European Economic Community
(Directive 83/351/EEC). ECE
R.15 urban test cycle.
Emission limit varies with
vehicle mass.

B. “Luxembourg HC + NOx: Standards to be introduced
1985” 1.4-2.0 1: 8.0 g/test during 1988-1993 in the
This standard only used European Economic Community,
to group technology as discussed at the 1985
(2.0 1: 6.5 g/test) Council of Ministers and
finally agreed upon in
December 1987. ECE R.15 urban
test cycle applies. Standard
for engines >2 1 is generally
equivalent to US 1983
standard. Standard for
engines1.4 1.

C. “Stockholm Standards for national
1985” legislation based on the
“master document’ developed
after the 1985 Stockholm
meeting of Environment
Ministers from eight
countries. Matching US 1987
standards, with the following
test procedures:
NOx: 0.62 g/km US Federal Test Procedure
(1975).
NOx: 0.76 g/km Highway fuel economy test
procedure.

D. “California NOx: 0.25 g/km Standards to be introduced in
1989” the State of California,
United States from 1989 models
onwards. US Federal Test
Procedure.

Table 3: Petrol engine technologies, emission performance, costs and fuel
consumption for emission standard levels
————————————————————————-
Standard Technology Composite a/ Additional b/ Fuel
NOx reduction production consumption
(%) cost (1986 index a/
Swiss francs)
————————————————————————-
A. Baseline (Current – c/ – 100
conventional spark-ignition
engine with carburettor)
B.
(a) Fuel injection + 25 200 105
EGR + secondary
air d/
(b) Open-loop three-way 55 150 103
catalyst (+EGR)
(c) Lean-burn engine 60 200-600 90
with oxidation
catalyst (+EGR) e/

C. Closed-loop three-way 90 300-600 95
catalyst

D. Closed-loop three-way 92 350-650 98
catalyst (+ EGR)

a/ Composite NOx reduction and fuel consumption index estimates are for an
average-weight European car operating under average European driving
conditions.

b/ Additional production costs could be more realistically expressed as a
percentage of the total car cost. However, since cost estimates are
primarily for comparison in relative terms only, the formulation of the
original documents has been retained.

c/ Composite NOx emission factor = 2.6 g/km.

d/ “EGR” means exhaust gas recirculation.

e/ Based entirely on data for experimental engines. Virtually no
production of lean-burn engined vehicles exists.

23. The emission standards A, B, C and D include limits on hydrocarbon(HC)
and carbon monoxide (CO) emissions as well as NOx. Estimates of emission
reductions for these pollutants, relative to the baseline ECE R.15-04 case,
are given in table 4.

Table 4: Estimated reductions in HC and CO emissions from petrol-fuelled
passenger cars for different technologies

————————————————————————-
Standard HC-reduction CO-reduction
(%) (%)
————————————————————————-
B. (a) 30-40 50
(b) 50-60 40-50
(c) 70-90 70-90

C. 90 90

D. 90 90

24. Current diesel cars can meet the NOx emission requirements of standards
A, B and C. Strict particulate emission requirements, together with the
stringent NOx limits of standard D, imply that diesel passenger cars will
require further development, probably including electronic control of the fuel
pump, advanced fuel injection systems, exhaust gas recirculation and
particular traps. Only experimental vehicles exist to date. (See also table
6, footnote a/).

Other light-duty vehicles (N1)
25. The control methods for passenger cars are applicable but NOx reductions,
costs and commercial lead time factors may differ.

Heavy-duty petrol-fuelled vehicles (M2, M3, N2, N3)
26. This class of vehicle is insignificant in western Europe and is deceasing
in eastern Europe. US 1990 and US 1991 NOx emission levers (see table 5)
could be achieved at modest cost without significant technology advancement.

Heavy-duty diesel-fuelled vehicles (M2, M3, N2, N3)
27. In table 5, three emission standards are summarized. These are used in
table 6 to group engine technologies for heavy-duty diesel vehicles according
to NOx reduction potential. The baseline engine configuration is changing,
with a trend away from naturally aspirated to turbo-charged engines. This
trend has implications for improved baseline fuel consumption performance.
Comparative estimates of consumption are therefore not included.

Table 5: Definition of emission standards

Standard NOx limits (g/kWh) Comments

I ECE R.49 18 13 mode test
II US-1990 8.0 Transient test
III US-1991 6.7 Transient test

Table 6: Heavy-duty diesel engine technologies, emission performance, a/ and
costs for emission standard levels

NOx reduction Additional
Standard Technology estimate (%) production
cost (1984 US$)

I Current conventional – –
direct injection
diesel engine

II b/ Turbo-charging + after-cooling 40 $ 115
+injection ($ 69 attributable
timing retard to NOx standard) c/
(Combustion chamber
and port modification)
(Naturally-aspirated
engines are unlikely
to meet this standard)

III b/ Further refinements of 50 $ 404
technologies listed under ($ 68 attributable
II together with variable to NOx standard) c/
injection timing and use
of electronics

a/ Deterioration in diesel fuel quality would adversely affect emission and
may affect fuel consumption for both heavy and light duty vehicles.

b/ It is still necessary to verify on a large scale the availability of new
components.

c/ Particulate control and other considerations account for the balance.