Today’s gas-to-liquids technology offers real commercial advantages to countries like Nigeria which produce far more associated gas than they can sell.It leads to an ultra-clean fuel that vehicle and genset operators can use with a clear conscience, too
GONE TO LAGOS” could be an alternative spelled-out form of GTL when Africa’s new 34,000 bpd gas-to-liquids plant comes into production. Or more precisely Escravos in the not-so-far Delta will be where customers of the Sasol/Chevron/NNPC joint venture to produce high-quality transport fuels, lubricants, naphtha feedstock and LPG will be heading.
Based on the renowned Fischer-Tropsch synthesis-gas family of proprietary technologies GTL in theory has been around for many years. South Africa’s Sasol has been producing liquid hydrocarbons from solid coal at Secunda since 1955, and natural gas – not available at that time, but now piped in from Mozambique - has special clean processing and usage advantages over its forerunner.
The company’s own three-stage low-temperature Slurry Phase Distillate (Sasol SPDTM) process will be used in its new joint-venture GTL plant in Qatar. In the 1970s the rival Shell Middle Distillate process was developed and a 14,700 bpd GTL plant, the world’s first, was opened by this major in 1993 at Bintulu in Malaysia, in association with NOC Petronas and Mitsubishi’s Diamond Gas.
In association with Qatar Petroleum the Pearl plant, at 140,000 bpd (GTL products) and 120,000 bpd (associated condensates and LPG), to be the largest in an admittedly small world, is now nearing completion. This brand-new method of commercialising gas offers enormous advantages so other companies have been working on their own proprietary developments to produce clean GTL products too.
Meanwhile the SA company which had to develop handy liquid fuels from tricky solids in the first place took advantage of its own oil-from-coal lead to develop GTL, even though this had little prospect for commercial development at home. It too went into partnership with gas super-rich QP; the government of Qatar and its partners had been scouring the world to find means of monetising the resources of its vast subsea North Field – and the resulting Oryx joint venture there went into production (capacity around eight million b/yr, with output still going up) in 2006.
So it has effectively been a race to win customers for this extraordinarily valuable new family of hydrocarbon processes which offer a combination of ultra-clean products and a way of making use of stranded gas.
The completion of construction and commissioning at Escravos – in 2011 although the original schedule called for completion this year? – should keep the two main international rivals more or less level pegging as each brings on stream a new billion dollar-plus plant, Pearl at least to be export orientated.
All GTL technologies convert hard-to-move gas
All GTL technologies convert hard-to-move gas – Nigeria’s vast and surplus associated supplies are an excellent example, but refinery waste products can also be used – into a very useful range of high-quality liquid fuels and speciality chemicals for which there is a good market in the polymers industry in particular. The common essential steps are the partial oxidation of the natural (cleaned up) raw material via gas reforming over catalysts into syngas which is then converted into a white waxy synthetic crude oil, suitable for cracking (in the Sasol version) by means of Chevron’s Isocracking™ technology. The really clever bits are the various catalysts used to help along the processes and the design and construction of the pressure vessels needed to cope with the conditions in which the sequence of automated operations take place.
Sasol has its own joint-venture cobalt-based catalyst plant overseas in Europe and is also in alliance with Japan’s Ishikawajima-Harima HI engineering consortium which builds the special reactors needed at Ras Laffan and Escravos.
Although not used to it for long customers like GTL fuels because they burn cleaner than conventional petroleum-based diesel, being almost devoid of sulphur, odours and resulting in few emitted pollutants such as the dreaded carbon oxides along with particulates. GTL diesel is claimed to extend engine life, too. It has good cold-flow characteristics in cold climates and can be used in unmodified engine/exhaust systems, unlike some of the fashionable biodiesels. And it can be used ‘neat’ e.g. by the civic-fleet operators who want minimal emissions and used to opt for inconvenient LPG, although the current trend is to offer it as a premium blend. This can be expected to become available in West Africa when Escravos comes on stream, with real advantages for air quality in go-slow Lagos.
Sasol is also active as a crude producer in Gabon and exports a wide range of SA-cracked products across land borders to several sub-Saharan countries.
From its Johannesburg headquarters the company says its own integrated GTL ‘solution’, while not being technically the first in the field, offers significant economic, strategic and environmental benefits for gas-producing countries like Nigeria that lack an adequate pipeline infrastructure. Apart from commercialising gas that would otherwise be flared or vented just one of these is that it promotes ‘dieselisation’ – the preference for more efficient compression-ignition engines by most commercial vehicle – and nearly all industrial genset - operators because of the combined safety, longevity and energy-efficiency advances these sturdily built reciprocating engines offer. The very clean exhaust resulting from a GTL diesel-fuelled machine is just a bonus on top.
Why breakthrough activity as far away as the Arabian Gulf and West Africa for a business headquartered in southern Africa? Because SA itself is desperately short of the world’s most favoured fuel of the 21st century and wants to help other developing countries, especially sub-Saharan ones, make best use of what they’ve got. And because its chemical engineers and theorists had the foresight more than half a century ago to develop processes to make liquid fuels from awkward non-liquid resources at a period when no-one else dreamed that oil supplies would