The pressure put on engine manufacturers and transporters in Europe, the USA and Japan to reduce harmful exhaust emissions has been well documented in these pages over the last few years. South Africa too is in the process of implementing clean air laws that apply to both ambient air quality and exhaust emissions. These laws have changed the way truck fuel injection and exhaust systems are made and in effect, changed the way many truckers with the latest technology under the cab go about their business. Modern diesel injector units run cleaner and more efficiently than their "rough 'n tough" predecessors, so while contributing to reducing harmful emissions from their exhaust pipes, these operators cut their fuel bills at the same time.
Smoke free or not
However, South Africa has a relatively old vehicle parc (15 years old on average) and many trucks still run old ADE technology. The new Euro 2 legislation to become law by January 1, 2006 will apply only to new homologations and to new registrations by January 1, 2010. Although our bigger operators are replacing their fleets with the latest technology trucks, many transporters out there are holding onto their old 'smokers' and running them with impunity. Some form of legislation needs to be put in place to restrict toxic emissions from old trucks.
Europe, the USA and Japan are a few steps ahead of us as far as enforcing emission laws on trucks is concerned. Euro 3 diesel, for example, has a zero sulphur content. Sasol is the only local producer of diesel that sells sulphur-free diesel. Sulphur, once it leaves the combustion chamber, becomes sulphur dioxide, a colourless toxic gas that once oxidised, produces sulphur trioxide, which becomes sulphuric acid, which in turn, is responsible for the sulphate particulate matter emissions. Sulphur oxides are the number one culprits when it comes to acid rains.
Bottlenecks in legislation
Next year, Europe will implement Euro 4 standards on toxic fumes coming out of truck engines. South Africa however will only be implementing Euro 2 standards. According to Mike Bond, the diesel specialist at Eurotype, "the Air Quality Act has been passed but there are great big holes in the legislation. The Department of Environmental Affairs and Tourism (DEAT) is responsible for the implementation of the Act but need SANS (South African National Standards [aka SABS]) to lay down the various rules and standards. Right now, no official metrics or standards exist."
This is disturbing. If DEAT is to effectively manage Euro 2 compliance among transporters by early 2006, it needs to chivvy things up a bit. Doctor Joseph Matshila, Chief Director of Pollution Waste Management at DEAT explains that "it's about setting attainable protocols. Minimum standards do need to be drawn up but care must be taken not to set the criteria too high that they become onerous or unachievable. Also, it's not only truck operators who pollute the air. Cars, factories and energy generators will also be restricted as far as the Air Quality Act is concerned."
Killing the poison
Once the new legislation is enforced, trucks will have to be fitted with special filters, exhaust gas recirculation (EGR) and catalytic converters. These components treat diesel exhaust gasses, which contain several constituents that are harmful to human health and to the environment. Carbon monoxide (CO), hydrocarbons (HC), and aldehydes are generated in the exhaust as the result of incomplete combustion of fuel. Exhaust hydrocarbons also come from the engine lube oil and have a negative environmental effect, being an important component of smog.
Nitrogen oxides (NOx) are generated from nitrogen and oxygen under the high pressure and temperature conditions in the engine cylinder. NOx consist mostly of nitric oxide (NO) and a small fraction of nitrogen dioxide (NO2). Nitrogen dioxide is very toxic. NOx emissions are also a serious environmental concern because of their role in smog formation.
Sulphur dioxide (SO2) is generated from the sulphur present in diesel fuel. The concentration of SO2 in the exhaust gas depends on the sulphur content of the fuel. Low sulphur fuels of less than 0.05% sulphur are being introduced for most diesel engine applications throughout Europe, Japan, the USA and Canada. In South Africa, diesel sulphur levels are around 0.5%.
Sulphur dioxide is a colourless toxic gas with a characteristic, irritating odour. Oxidation of sulphur dioxide produces sulphur trioxide, which is the precursor of sulphuric acid, which, in turn, is responsible for the sulphate particulate matter emissions. Sulphur oxides have a profound impact on environment being the major cause of acid rains.
Gas Technology engines from
Mercedes Benz - avaliable in Europe only - make a valuable
contribution to the environment - near zero sulphur
dioxide and nitrogen oxide emissions - no
smoke and no
Green truck devices
Diesel emissions are controlled either at their very source, through engine design and modifications, or by exhaust gas aftertreatment. The two approaches are in fact complementary and are followed simultaneously in real life. There are two groups of diesel exhaust aftertreatment devices: diesel traps and diesel catalysts. Diesel traps, which are primarily diesel filters, control diesel particulate matter emissions by physically trapping the particulates. The major challenge in the design of diesel filter system is to regenerate the trap from collected particulate matter in a reliable and cost-effective manner. So far diesel filters are used commercially only in a few specialised diesel engine applications.
Diesel catalysts control emissions by promoting chemical changes in the exhaust gas. They are most effective towards the gaseous emissions, i.e., hydrocarbons and carbon monoxide. Modern diesel catalysts are also becoming more and more effective in controlling diesel particulate matter. Diesel catalysts have been commercially used for many over-the-road and off-highway applications.
According to Satha Govender, Technology Manager at Castrol, "the motor oil industry has been producing innovative products aligned with new vehicle technology and emission control devices. New means of treating exhaust and similar emissions have had to be developed. This has led to the implementation of various after-treatment devices such as catalytic converters and particulate filters made of palladium and platinum. Unfortunately, leaded fuels and lubricants deposit heavy metals on these devices, causing clogging which renders them ineffective. Consequently, Castrol has developed a range of lubricants with lower sulphur and phosphorous content to complement the cleaner fuels strategy, thereby ensuring that emission levels are effectively reduced." He adds that with improved fuel economy comes less frequent oil chang intervals, which reduces the amount of oil that needs to be disposed of.
DaimlerChrysler has developed SCR (selective catalytic reduction) technology, which converts polluting nitrogen oxides into harmless nitrogen and water vapor by adding ammonia in the form of a carbamide solution as a reducing agent in a catalytic converter. The carbamide solution, named "AdBlue," is a non-toxic, colorless, odorless and water-soluble substance. A vehicle's AdBlue consumption when meeting the Euro 4 standard will be about six percent of the diesel fuel used. With a 100-litre tank, for example, that corresponds to a range of more than 5,000 kilometers. There are no additional maintenance costs for the SCR-specific components such as the catalytic converter, dosage control system or tank. In addition to the savings offered by SCR, the technology also has the advantage that it is not dependent on the availability of sulphur-free diesel fuel.
Exhaust emissions kill. They need to be outlawed. This means government has to really put its money where its mouth is - legislate standards and effectively enforce them. Right now, even smoke legislation is not being policed. It's a case of "in Africa, anything goes". There are mobile devices available that measure a spectrum of harmful exhaust gasses and Traffic officials should be trained how to use them. Says John Schnell, KZN Traffic Directorate, "emission testing should be linked to the transport industry's annual Certificate of Fitness examination, but this won't be easy to achieve because of fairly sustained industry resistance to compliance because of the costs involved."
do their bit. Regular servicing,
ensuring the use of good
and oil, promotion of driver training and driving style, prevention
of over-fuelling resulting
in under-combustion and billows of smoke ...
Do your bit
And one can sympathise with truck operators on this score. Diesel quality when used in new technology injectors is a problem, an expensive one at that. Spending money on Euro 3 truck-technology just doesn't make financial sense at this stage in South Africa, which is why Euro 2 from an emissions perspective in SA is still a pipe dream. However, truck owners can do their bit while government and the fuel companies get their act together by optimising engine combustion to minimise the production of pollutant particles from the start. Regular engine servicing is crucial, as is ensuring only good quality diesel and oil goes into it. Additives like Fuel Effect and Algae X are starting to prove themselves as combustion optimisers as reducers of toxic emissions. Driving style is also a key factor in reducing smoke emissions. Over-fuelling the engine while driving results in undercombustion and billows of smoke. Operators need to train and monitor their drivers (via whatever means necessary, be that the old beady eye, tachograph or electronic fleet management systems) to ensure optimum combustion. In short, the days of smoking rigs are seriously numbered. New truck technology and new sulphur-free diesel are working hand in hand with government to eliminate emissions. If transporters resist these initiatives, they too will be eliminated.