The UK has moved to sulphur-free road fuels (sulphur content not exceeding 10 parts per million or 0.001% by weight).
Petrol and diesel are a complex mixture of many individual hydrocarbon components produced by refineries and blended together to meet specific market requirements.
Sulphur is usually reduced to the required level by a combination of using lower sulphur crude oil and the physical removal of the sulphur from the blending components. This has required substantial investment in hydro de-sulpherisation (HDS) plants at refineries. In addition to capital costs, the removal of sulphur also requires the use of additional energy and other materials (primarily hydrogen), thus increasing refinery operating costs.
Background to their introduction and timetable
Primarily, these fuels are being introduced to improve air quality.
In 1993, the European Commission set up the 'Auto-Oil programme' to work with EU oil and motor industries to identify the most cost-effective means of improving air quality across Europe. These measures were designed to improve urban air quality across Europe by 2010. Based on the recommendations of the programme, two Directives were published in December 1998 to achieve improvements to vehicle technology and fuel specifications.
The first (98/69/EC), set tighter limits for emissions from cars and light vans to apply from 1 January 2001, with more stringent limits to come into force from 1 January 2005. The second (98/70/EC) required all petrol and diesel fuels to be manufactured to new, cleaner specifications also from 1 January 2000 and mandated the use of ultra low sulphur petrol and diesel from January 2005. Subsequently this Directive was amended, requiring member states to move to sulphur-free petrol and diesel (10ppm or less), starting in 2005 and completed by 2009. In the UK, the path to lower sulphur fuels started early on. For diesel, the sulphur level was reduced from 500 ppm to 150 ppm on 1 January 2000 and again to 50 ppm in mid 1999 (in the case of petrol, mid 2001).
Although the EU Directive required that sulphur-free fuels (10ppm or less) be made available on a 'balanced geographic basis' starting in 2005, UKPIA member companies had already invested at refineries to produce these new cleaner fuels, in response to Government announcements that early introduction was to be encouraged through a duty differential. However, this approach was shelved in 2004/05 as a consequence of continuing high oil prices. The Department for Transport published in early 2007 regulations setting out the timetable for introduction of sulphur-free fuels to meet the deadline of January 2009, contained in the EU Directive.
Diesel and super unleaded petrol met this specification by 4 December 2007. All road fuels have met the specification since the start of 2009. The oil industry has invested close to £1bn to meet these standards.
The virtual removal of sulphur should improve the efficiency and prolong the life of exhaust catalysts.
Additionally, sulphur-free petrol is "enabling technology" in that it optimises the efficiency of new direct injection petrol engines that improve fuel efficiency and reduce emissions of carbon dioxide when combined with de-NOx exhaust catalysts.
Sulphur-free diesel should also slightly reduce nitrogen oxide emissions from diesel engines and assist the efficiency of vehicles fitted with re-generative particulate filters within the exhaust system.
However, it should be borne in mind that the increased processing at refineries to make sulphur-free fuels also uses more energy and these increases in CO2 emissions may offset, to some extent, the gains made in these new vehicles.
Fuels for Non Road Mobile machinery (NRMM)
The EU's Fuel Quality Directive (2009/30/EC) has introduced a requirement for all gas oil for use in NRMM to be virtually sulphur-free (sulphur content not exceeding 10 parts per million). In the UK, the directive was transposed such that NRMM met this requirement by 1 January 2011. Under EU derogation, fuel for rail locomotives have met the sulphur free requirement from 1 January 2012.
The UK's gas oil standard BS 2869 has been updated to reflect these changes.