South African Exhaust Emissions

Examines the Goods Vehicle Exhaust emissions against the general South African air quality and the need, or otherwise, to legislate for a higher Euro emission standard
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  South Africa ’ s Diesel Exhaust Emissions    –   the next step The Beginning Smog is the common International term for the forms of air pollution involving haze and oxidants such as ozone. Smog was identified as a serious problem in the Los Angeles Basin in the 1950s. As university scientists and US government health scientists investigated the problem, they found that vehicle emissions were a significant source of smog precursors.  Acting on this information, the California Legislature established emissions limits for 1966 model year cars and 1969 model year diesel trucks. Roll on two decades, and a rising, and ever more affluent, population burning ever more fuel saw California‟s problems become a world wide phenomenon in cities and countries with high density populations. Welcome then, in 1988, to the first of the European emission regulations that were to be popularly named EURO 1-6   South Africa’s air quality   If it ain't broke don't fix it!   Measures that California found necessary to solve their pollution problems way back in the middle of the last century were not necessary for the rest of the States for decades. Similarly, South Africa‟s forests, fire damage apart, continue to remain intact, unaffected by the acid rain that was destroying European forests and that was a major signal for the need for Europe to act. We quote from National Association for Clean Air (NACA):- “South Africa is plagued by a number of pressing and persistent air pollution problems in addition to facing various new emerging air pollution issues. High ambient sulphur dioxide and fine particulate concentrations experienced in many urban areas are due primarily  to fuel burning within the household, industrial and power generation sectors .”   “More than 90% of South Africa's electricity is generated from the combustion of coal that contains approximately 1.2% sulphur and up to 45% ash. Coal combustion ca n lead to particulate matter in the air, as well as contribute to acid rain.” “ Total respiratory hospital admissions across various South African conurbations were calculated to be in the order of 120 000, with total direct health costs due to respiratory conditions related to fuel-burning emissions being estimated to be in the order of 2002 cases, which is equal to a cost of R3.5 billion. Residential fuel burning was estimated to result in the greatest health risks  accounting for approximately 70% of all respiratory hospital admissions due to fuel-burning exposures ” .   “ Many new and emerging air pollution issues relate to the transportation sector, particularly road transportation ” . Beware that statements such as the last sentence are not quoted out of context. Sure exhaust emissions are the main, if not only, emerging pollution, but that still does not mean that exhaust emissions should be prioritized over long standing and much larger polluters [If one wants to polish ones marbles by quoting selectively we can pick out from the University of the Witwatersrand, Faculty of Sciences document whereby air samples from sites in the Western Cape and Gauteng were broken down far more than in „normal‟ analysis (into 16 individual elements) in order to zone in to their true source:- “Source apportionment show that the major sources of atmospheric aerosols at t he Khayelitsha sampling site were sea salt and wood burning. The soil dust and   gasoline emission contributes little percentages. This is also in agreement with the  previous study undertaken at the site, which shows that PM10 contributes to air pollution (Wicking-Baird et al., 1997; Walton, 2005).”   “Source apportionment shows that the main contributors of air pollution at the Ferrobank site are soil dust and coal burning. Gasoline   contributes only 0.913 %”]   The above, opening, statement from „NACA‟ then brings one to suppose that the National Environmental Management:  Air Quality Act, Act No. 39 of 2004 has not been enforced to restrict the major atmospheric polluters, and rather than address that, the South African legislators will continue their practice of churning out more legislation without reference to  the fact of non enforcement of previous. Legislating the full might of European vehicle emission control, a control designed to maintain air quality on countries that use 15 times more diesel  per square kilometre than South Africa. Europe v South Africa .   Diesel With a density of +/- 0.832 kg/l, some12% more than petrol at +/ 0.745 kg/l, diesel fuel offers a higher volumetric energy density (typically 35.86 MJ/L ), which, combined with the intrinsic efficiency of the diesel engine, results in the better  fuel economy and lower  greenhouse gas emissions that makes diesel power the standard for freight movement, and a rising favourite in the car market ( While diesel's higher density results in higher greenhouse gas emissions per litre compared to petrol the 20   – 40% better fuel economy achieved by modern diesel-engined vehicles offsets the higher per-litre emissions of greenhouse gases, and a diesel-powered vehicle emits 10   – 20% less greenhouse gas than comparable petrol-powered vehicles ) The processing required to remove sulphur results in a fuel that has a lower energy content compared to the higher sulphur fuel; fleets could see a fuel economy penalty of 1 % to 2% percent. The road to „clean diesel‟ is already the subject of Government Gazette 35393, although the Country‟s legislators confuse all, by referring to the diesel as „low sulphur diesel‟ a term which in the real world refers to diesel with more than 50ppm of sulphur. The Gazetted target date of 2017 for introduction of „ SFD ‟ has already been deferred to 2020.  The accepted world-wide (except South Africa!) terminology for diesel cleanliness is Low Sulphur Diesel (LSD)  > 50 ppm (Upper cut off appears to be anything from 300ppm to 3000ppm) Ultra Low Sulphur Diesel ( ULSD ) < 50ppm Clean Diesel or Sulphur Free Diesel ( SFD ) < 10ppm The reduction of sulphur in diesel is a stand alone programme, there is no such thing as Euro 1, or Euro anything, diesel. „ Clean ‟  diesel does not make an engine perform better, it does give better oil life because of the cleaner burning, and it does, in itself, reduce emissions (tests have shown about 8% in going from 2000 ppm to SFD, < 10ppm). The real need for it though is to prevent contamination of the expensive exhaust system that is very necessary for the higher stages of the Euro programme. In essence view it as a mirror of the move, a decade or more ago, to un-leaded petrol in order to stop poisoning of the „catalytic converter‟ . Population 2010Land Area Population Density Vehicles Vehicle Density Diesel ConsumedDiesel Consumed (Sq Km) (per Sq Km) (per Sq Km) (KiloTons 2009) (Kg/sq km ) South Africa  49,991,000 1,219,912 36  10,979,208 9  6699 5491Euro (5 Country sample)222,750,000 974,871 228  112,312,034 115  80,212 82279 Belgium 10,827,000 30,510 339.71 4,668,030 153.00 7113 233148Germany 81,758,000 357,021 230.89 44,270,604 124.00 26408 73967Italy 60,340,000 301,230 192.89 34,641,450 115.00 22688 75317United Kingdom 62,042,000 244,820 246.88 24,726,820 101.00 21777 88950Switzerland 7,783,000 41,290 181.39 4,005,130 97.00 2226 53910  Much has been speculated about how much we will pay for clean diesel, but the international industry estimates that the whole process journey, from 3000 ppm to < 10 ppm, to add, only 2.5/3 US cents per litre. Considering that our current diesel price has already absorbed the move from 3000 ppm to 500ppm, and that the current regulated wholesale price difference between 500 ppm and 50 ppm is less than 1 US cent, it would seem difficult to charge more than a few local cents for clean diesel - without moving away from the country's current „Basic Fuels Price‟ policy of pricing based on world markets. (“BFP relies on “spot” [cash] F.O.B prices quoted in „ Platts ‟  which tracks actual daily fuels trading prices at export refineries ”)   The Euro Exhaust Emission Programme   With the final, sixth stage, of the Euro programme coming into force in January 2013, we have benefit of a full picture of what has been necessary to get there, the problems, pitfalls, and the necessary ongoing management necessary to maintain compliance. Whilst there is no difficulty finding the emission standards for the various Euro levels, it is difficult to find emission levels before the programme started. B ut the UK‟s RSSB carried out some well documented tests on a variety of 200-300Kw Perkins and Cummins engines, testing the effect of, and the differences between, fuel at 2000 ppm & SFD diesel. Their averaged emission figures for 2000ppm diesel have therefore been used in the following table to set the „pre Euro‟ emission level. All Quantities gm/kw/hrNitrogen Oxides% over previousTotal Hydro Carbons% over previousCarbon monoxide% over previousParticulate Matter% over previousAveraged % improvement% move towards Euro 6Pre Euro 18.0028.361.1048.434.500.3638.9828.94  35 Euro 27.008.951.  43 Euro 35.0017.910.6620.632.1021.250.1025.4221.30  69 Euro 43.5013.430.469.381.5022.500.0213.5614.72  86 Euro 52.0013.430.460.001.500.  91 Euro 60.4014.330.1315.471.500.000.011.697.87  100   Whilst there is no suggestion the above table is „ clinically ‟  correct (with arguments existing for weighting one pollutant against another in averaging figures), the straight mathematical average of emission reduction from stage to stage does enable the establishing of an overall percentage move towards the current, and generally considered ultimate, stage 6. From which an approximation of the progress towards Euro6 achieved by each stage, and the identification of diminishing returns against escalating costs of Euro 4 onwards, can be shown. (The recent November forum held by the IRTE, with a panel representing manufacturers from the 5 world wide sources of our new truck supply, China, Europe, India, North & South Americas, did little to suppress the widely reported view that trucks to the highest European emission standard would carry a 10% price premium - the only caveat being that in the medium to long term, with volume production and development costs recovered there could be a normalizing of prices). Progress up to, and including, Euro 3 was achieved through advances in engine design; substantially combustion efficiencies through higher and higher injection pressures, multi phase injection, „modest‟ increases in Exhaust Gas Recirculation („EGR‟) , and the fuel consumption increasing penalty of retarding ignition to reduce peak flame temperatures. Costs were largely development, with little in the way of additional components, and with Euro3 having been introduced many years ago in Europe, those costs have long since been absorbed. Euro 4 saw the manufacturers forming 3 distinct camps, those opting to achieve it by high levels of „EGR‟, those introducing Exhaust Gas Treatment („EGT‟), and those already taking the road that was to become the definitive route for Euro 5 & 6, a mix of the two. In the move from Euro 5 to Euro 6 internationally renowned Ricardo suggests manufacturers will achieve somewhere between equal to Euro 5 and a small, up to 3%, fuel consumption increase. Both these routes to progressing beyond Euro 3 have problems over and above the expense of introducing extra components, problems which only become magnified in an African situation. EGR    Exhaust Gas Recirculation (EGR) is a process whereby some of the engine exhaust is fed back into the intake. Since NOx formation is extremely sensitive to temperature, by replacing some of the intake air with inert exhaust gas, the flame temperature can be reduced by a small amount and the NOx emissions can be reduced without seriously affecting the combustion efficiency. EGR as an emission reduction solution is not new, with both diesel and petrol engines being so modified some 50 years ago in order to satisfy early Californian regulations, but for many years it was fairly small volumes of exhaust gas that were being reprocessed, most certainly no more than 15%.  As with the early, low boost, days of turbo charging, there was no requirement to cool the gas before entering the cylinder. But with current techniques demanding 40%, or more, of EGR, cabs have had to be redesigned, even in temperate climates, in order to provide space for the now necessary additional cooling. Local temperatures just magnify the problem, and at least one local „manufacturer‟ is on record as saying EGR at these levels is a no go in Africa. High volume, cooled, EGR allows a more controlled burn at lower combustion temperature and reduces NOx emissions levels, but the lower combustion temperature creates more Particulate Matter („ PM ‟)  which has to be captured by a Diesel Particulate Filter („DPF‟) in the exhaust system.   Unavoidably creating a higher back-pressure on the engine and a fuel consumption penalty of, typically, about 1%. It must be remembered that little more than 2 decades ago the space at the front of a truck was only needed to cool the engine, then power went up and the radiator grew bigger; then the gearbox manufacturer wanted a slice of the action with a need to cool his gearbox; then as turbo charging boost levels increased, intake air had to be cooled; radiator four came next as the driver overheated and in went air conditioning; and now the need to accommodate for the cooling of „red hot‟ exhaust gases! Cooling problems apart, EGR offered the more attractive way forward, with no complications of additive injection and reservoirs and, being part of the „engine package‟ , offering long life, minimal opportunity to abuse, and little, if any, additional maintenance. Effectively a Just Diesel, Nothing Else solution. EGT EGT alone (at Euro4), or together with EGR (Euro5+), requires the complexity of Selective Catalytic Reduction („SCR‟).  Against the EGR‟s “just diesel” solution, t he addition of the SCR system has been described as “ akin to bolting on a mini chemical treatment plant ” . With the SCR solution to emissions, the higher combustion temperature in the engine (compared to SGR) creates less PM but more NOx. SCR technology then uses a chemical fluid called Diesel Exhaust Fluid („DEF‟), or urea, and a catalytic converter to reprocess the exhaust gases and reduce the NOx emissions. The injection of the urea resin (known as  AdBlue in Europe) into the exhaust system permits the conversion of NOx into water vapour and nitrogen, which is harmless. AdBlue is added to a special tank generally attached alongside the fuel tank. SCR is more convenient for the manufacturer because it requires little, or no, actual engine development, allows injection timing to be re-advanced, typically to the optimum Euro 1 settings, cutting soot levels dramatically and extending oil changes to 200,000 kilometres. Against that is the need to find chassis space for the „chemical treatment plant‟ and urea tank, the cost and weight penalty of up to 140Kg, increasing back pressure considerations, and, since NOx stores on the surface of the exhaust‟s platinum coated catalyst  during low power, stop/start type operations, it needs to be regenerated by frequent short spells of rich running imposing a consumption penalty of at least 2%, (with 4% or 5% not uncommon), negating the promised fuel consumption improvement through combustion optimisation. Lubricating oil manufacturers who have in the past focused development entirely on how oils perform in the engine, now have to be concerned about how properties of the oil may affect emission control technology downstream of the engine. This is going to place new physical and chemical limits on oil.”  The operational weakness of the EGT/SCR solution is that failure to refill the DEF reservoir has, in itself, no effect on the vehicles performance, unlike the fuel tank, where the driver has the incentive of keeping diesel in order to get home. Thus since failure to fill the DEF reservoir has only the effect of ruining a R 100,000 exhaust system and leaving the driver/owner open to prosecution for a „dirty‟ exhaust, legislation, even the disciplined world, has had to specify the complexity of on board computers („OBC‟s‟)  to monitor the reservoir level, the actual injection into the exhaust, and warn drivers of an impending problem; and then, failing any remedial action, shut down the engine. Given the local climate of removing, or by-passing, anything that causes a problem, and the lack of law enforcement, one sees little but a lot of very expensive exhausts being negated in little time? Conclusion
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