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Exhaust Emissions
Ultra Low Sulphur Diesel
Euro 3 - Euro 6 engines
Recycling
NCT as a company tries where ever possible to be environmentally friendly, we recycle many of the parts and waste we produce. To find out more about how and what we recycle, click here.
- Engine Oil
- Filters
- Bus bodies
- Tyres
- Paper
- Scrap metal
The Greenhouse Effect
Exhaust Emissions What are diesel fumes?
Diesel engine exhaust emissions (commonly known as 'diesel fumes') are a mixture of gases, vapours, liquid aerosols and substances made up of particles. They contain the products of combustion including:
- carbon (soot);
- nitrogen;
- water;
- carbon monoxide;
- aldehydes;
- nitrogen dioxide;
- sulphur dioxide;
- polycyclic aromatic hydrocarbons.
The carbon particle or soot content varies from 60% to 80% depending on the fuel used and the type of engine. Most of the contaminants are absorbed onto the soot. Diesel engines produce less carbon monoxide but more soot than petrol engines.
The quantity and composition of diesel fumes may vary depending on:
- the quality of diesel fuel used;
- the type of engine;
- the state of engine tuning;
- the fuel pump setting;
- the workload demand on the engine;
- the engine temperature;
- whether the engine has been regularly maintained.
What are NCT doing to Reduce Exhaust Emissions
NCT have been aware of the environmental issues surrounding exhaust emissions for a considerable time, we have taken many measures to ensure that we are doing everything possible to reduce the exhaust emissions from our buses.
We currently use Ultra Low Sulphur Diesel (ULSD) in all our vehicles and have done so since 1999. ULSD reduces the amount of particulate matter released into the atmosphere from exhaust fumes. For more information on ULSD click here.
Emissions tests on vehicles - a sample of the exhaust emissions are tested and analysed. The results are printed, and the vehicles pass or fail depending on the percentage of toxic emissions in your sample. NCT ensure their bus fleet is within the government exhaust emissions guidelines by testing all their buses every 6 weeks to make sure these standards are maintained.
Exhaust emissions from idling engines contribute to air pollution, drivers can make a significant impact on the health of their passengers and their own health by limiting engine idling whenever possible. NCT drivers are asked to turn their engines off to prevent unnecessary use of fuel and therefore cut down the exhaust fumes released. This also helps reduce noise pollution.
The Greenhouse Effect - how it affects us
The number one impact of human activity on climate is to increase the "greenhouse effect". It threatens to be global, long lasting and hard to reverse. The gases that contribute to the effect are being emitted from our power stations and vehicle exhaust pipes, our farms and our forests and they can stick around in the air for decades, even centuries.
Some of these greenhouse gases are naturally present in the air. They help keep the planet warm. It works like this. As the sun's ultraviolet radiation hits the Earth's surface, some of it is reflected back into space, but much of it is absorbed by the land and oceans as infrared radiation—or heat. Some of the heat escapes into space, but a lot is trapped by greenhouse gases close to the Earth’s surface, causing the atmosphere to heat up.
Pumping greenhouse gases into the atmosphere is like putting an extra blanket over the Earth. We are starting to warm up. And there are other changes. Higher temperatures increase evaporation from the oceans and increase the atmosphere’s capacity to hold water. So, the air is getting wetter in many areas. And a hotter atmosphere is more energetic, so that it is able to generate stronger storms and other extreme weather events.
Ultra Low Sulphur Diesel
Ultra Low Sulphur Diesel (ULSD) is a high specification more environmentally friendly diesel than the standard European grade. ULSD has a maximum sulphur level of 50 parts per million (ppm), this is 10 times less than standard diesel.
Less sulphur means less sooty black exhaust smoke and as most of the contaminants are adsorbed onto the soot it means less are taken up. Invisible emissions have also been greatly reduced, and carbon monoxide, hydrocarbons and nitrogen oxides are now just a fraction of their former levels.
As well a low sulphur level, the ULSD NCT uses has a high cetane number giving easier starting, swifter warm-up and reduced white smoke. Additionally it is low in polyaromatics which aids the reduction of particulate emissions.
All of which adds up to a cleaner, healthier environment for everyone and everything.
Sulphur from exhaust fumes - what does it do to the environment?
 Approximately half the Sulphur dioxide in the atmosphere comes from the burning of fossil fuels. Once Sulphur dioxide reaches the atmosphere it can react with moisture in the air - clouds, forming sulphuric acid, this then falls as acid rain.
The acid rain is absorbed into the ground changing the PH of the soil and releasing otherwise insoluble aluminium, washing it into streams and lakes.
Aluminium and acidity have a profound effect on freshwater ecology, causing problems with the gills of fish preventing them from getting enough oxygen, they then die, this then has repercussions  all along the food chain with the stream/lake often becoming more acidic over time, supporting less species and more algae.
The acid rain also affects plants and trees, the acid rain filtering into the soil releasing the aluminium and leaching out minerals necessary for the plants survival. It also has effects on the leaves one which prevents photosynthesis and the other prevents the leaves natural frost hardiness.
Nitrogen Oxide is also emitted as exhaust fumes and contributes to smog, acid rain and ground level ozone. With tighter emission regulations, things are changing. Sweden is one of the countries leading the way in the research of reducing these emissions (which is where Scania our main supplier of buses is based). The engines which recirculate the exhaust gases EGR (Exhaust Gas Recirculation) are the next engine types (euro 4) to go into the Scania fleet.
Euro 3 - Euro 6 engines, what are they?
Euro 3 - Our current engine type. The City Council require that buses entering the "clear zone" (more information about clear zone) are of Euro 2 and above or hold a Reduced Pollution Certificate. All of NCT's vehicles have passed this criteria and we are always looking at new technology and initiatives in this field to keep our fleet moving towards a cleaner, greener and more environmentally friendly one.
Euro 4 - For the forthcoming Euro 4 legislation Scania our main supplier of buses has adopted two entirely different technologies: EGR (Exhaust Gas Recirculation) and SCR (Selective Catalytic Reduction) to further reduce emissions from diesel engines. This two-pronged strategy makes it possible to tailor solutions that are appropriate for different applications be precisely controlled at relatively low temperatures. This is the only way to reduce NOx emissions during combustion.
Developing combustion technology is largely about finding a reasonable balance between fuel consumption and the formation of nitrogen oxides.
With EGR, Scania attacks emissions at source – in the combustion chamber. No additives are needed and the vehicle can operate on the diesel fuel available at any pump. Scania EGR is a straightforward solution that combines lower emission levels with excellent operating economy with any type of diesel fuel. The fact that no additive is required means that these Scania Euro 4 vehicles can operate anywhere, without any worry about the availability of additives. These engines will feature Scania’s own engine management system as well as Scania’s high pressure fuel injection system (Scania HPI) and in some cases turbocompounding to achieve optimum economy. This enables overall operating cost to reach Euro 3 levels, despite considerably lower emissions, both of nitrogen oxides and particulate matter.
Euro 5 - Scania is continuing to develop EGR and SCR solutions towards even lower emission levels. For example, the step to Euro 5 will require even higher injection pressures and even more sophisticated combustion control. This will be achieved using Scania XPI (extra high pressure injection) – a common-rail fuel injection system being developed jointly by Scania and Cummins. Combinations of EGR and SCR are likely to make it all the way to what is expected to be Euro 6.
Euro 6 - By the time this is developed the emission levels from diesel engines will be so low, at least of the exhaust components regulated today, that other issues will take over. Concerns about car-bon dioxide emissions and the green house effect are with us today and this focus will increase. Concerns about the availability of crude oil will increase the need to use the most fuel-efficient engine techno-logy.
Recycling
 Oil - our waste oil is collected and every month Eco Oil pick it up for reprocessing and re use.
Oil Filters - All our used filters are collected in special bins, Greenway Orcol collect these bins and environmentally recycle the filters by removing any excess oil from them which is then reprocessed, metals that are part of the filter are removed and recycled also.
Scrap Metal - separate bins are provided to separate the light steel, heavy steel, non ferrous, ferrous, copper and other metals. these are then collected by Linby Metals who recycle them for other use.
Paper and Cardboard - Kappa Waste (a Seven Trent owned company) regularly come in to remove the paper and cardboard that has been collected from our offices and stores to recycle this for other uses.
Bus Bodies - The metal bodies on our buses are made of aluminium, a very good metal for recycling, we don't very often scrap any of our buses for recycling as we generally sell them on to other bus companies.
Drains - Our industrial drains which collect all the wash waste from our chassis washes and bus washes is collected by Supa Kleen of Newark, who will in future be recycling this and using it for mulch in fertilisers.
Engine Parts - Our engine parts, bolts and washes etc are all sent to Safety Clean where they are placed into a cleaning substances and all grime etc removed from them, they are then available for reuse.
Tyres - NCT don't actually own the tyres on the buses, they are owned and maintained by Michelin who have permanently based staff at our garages to maintain and replace these tyres.
Water - the water used to daily to wash our bus fleet is recycled, cleaned and reused.
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