January 9th 2012

"Bacton Processing Plant and the World of gas"

          Dr Rob Nibbelke
Shell U.K.

This talk had been postponed from October 2011 owing to Rob, the plant manager for the Shell Bacton Gas plant, being called away on business to Qatar, a key resource for liquid natural gas (LNG) in the Persian Gulf which provides an essential component (~25%) of the UK’s current gas supplies.

To a large audience of well over 100, Rob started his talk by outlining key points which he would address:-

	'The World of Gas'
	'Gas Processing'
	'The Shell Bacton Plant'

In looking generally at energy requirements for 2050, with a possible planet population of 9 billion people, the population being 4-5 times richer, and double the current energy needed with a doubling of overall efficiency in its usage, an extrapolation would predict 6 to 10 times more renewable energy would be required. Challenges for future energy supply include:- security of supply (~60% of UK natural gas is now imported), safeguarding the environment, and societal concerns.

Rob point out that the case for gas as a prime energy source is based on three factors:-

	(a) its abundance - it is estimated that supplies for ~250 years are available in the world
	(b) its acceptability – it generates 50-70% less carbon dioxide than coal
	(c) its affordability – gas power stations are cheaper to build and have similar operating costs to coal and nuclear plants.

There are huge global reserves of gas, both ‘conventional’ and unconventional (e.g. shale gas).



As regards future demand, it is estimated 50% will come from Asia, and future supplies will be very dependent on Russia, the Middle East, and Africa. Gas provides the cheapest option for satisfying the projected demand and its acceptability is based on it being the cleanest burning fossil fuel.

Growth is clearly required to meet future demand – a figure of $200 billion per annum was suggested as investment needed in the gas industry and it was conjectured that one-half of the production in 2025 would come from fields not producing today. As regards supply and demand in Europe, imports are set to increase with outlooks for moderate growth or flat demand.

Natural gas is abundant and accessible; a key question is its transport from source to site of use. In this regard pipelines are clearly attractive but over long distances the transport of natural gas in the liquefied form (at -161 °C) becomes cheaper. Refrigeration during transport is not necessary since controlled evaporation keeps the remaining liquid cold and the gas produced can be used to drive the turbines which propel the ship. Alternatively the boiled off gas is re-liquified.




It is encouraging (for Europeans) that 70% of global gas is within relatively easy reach of Europe. Figures of import capacity, past and projected, were compared: 43 bcm in 2005 and 145 bcm in 2025.

Since there is a considerable network of pipelines which are connected with the UK, there is the possibility that it will become a hub for reception and distribution of gas supplies.

Gas trading via pipelines, utilising the daily variation in its price to advantage, can clearly lead to attractive profits. However, gas storage by pumping back into empty wells can make for economic difficulties and Shell is not involved in this aspect of gas storage at this time.



As regards acceptability in meeting future carbon dioxide targets, gas power stations may be built in approximately half the time taken to build coal and nuclear plants – a typical figure of over 50 months was given for building the latter types. Since generation of electricity by wind power is bound to be of an intermittent nature, the continuing necessity of power generation by conventional means is clear.

Rob then focused on the position of Shell as a company in the field of fuel provision (gas and oil) for power generation under the headings of its leadership (in exploration, production, and size – it is one of the world’s largest companies in the field), gas liquefaction (the largest supplier of liquefied natural gas, LNG), shipping of LNG (the largest ship operator for this purpose), LNG re-gasification and storage (holds a strategic position), market and trading, and technology.

LNG is now a very important part of the supply line and typically has the advantage over the pipe-transfer of gas when a pipe line exceeds 3000 km. It consists predominantly (~90%) of methane with small amounts of ethane, propane, and butane.

The World's largest floating structure so far that is in the construction planning stages – essentially an enormous barge - is an offshore gas liquefaction plant which measures 480 x 75 metres and weighs 600,000 metric tonnes. The platform will be moored close to the well head and can be moved to a new well when required.

A vessel for transportation of the LNG is moored alongside during transfer and such an arrangement removes the need for expensive docking facilities which would otherwise be required for an on-shore installation.





An important development that has taken place over the last 40 years is the chemical conversion of natural gas into oil products, a process which started for Shell on a laboratory scale in 1973 and today can produce, in Qatar, 140,000 barrels/day.

The processing of natural gas is also dependent on chemistry since at the well head, apart from 70-90% methane and lower proportions of ethane, propane, and butane, it contains water, carbon dioxide, hydrogen sulphide, traces of mercury, nitrogen, and in addition gasoline condensates consisting of hydrocarbons with higher molecular weights, that is more than 5 carbon atoms per hydrocarbon molecule.

After purification, gas properties have to ascertained e.g. the heating value and flame characteristics, the latter being indicated by the Wobbe index which compares the combustion energy output of different composition fuel gases in an appliance (fire, cooker, etc.) The purification processes for natural gas can involve the use of refrigeration, distillation and absorption with specific filters. The gasoline condensates from Bacton are transferred through pipeline to the North Walsham rail terminal for transport to customers in the petroleum industry for processing by distillation, etc.


The UK gas supply comes from several sources, the most obvious being direct from the UK continental shelf. However, supply also comes from pipelines connected to the continent, the Interconnector UK (IUK) connected to Zeebrugge, Belgium and the BBL Pipeline connected to the Netherlands. Import of LNG is also of great importance. The Bacton terminal supplies 20-25% of the UK requirements and receives inputs from the Sean and Leman fields in the southern North Sea and via the SEAL Pipeline which connects to gas fields in the Northern North Sea.

Rob’s talk was an excellent, clearly delivered presentation, well illustrated with slides and delivered with a nice sense of humour. He happily answered questions during his talk, and the number of these clearly indicated that he had captured the interest of the very large audience. Time restraints precluded more potential questions and Tony Meacock proposed a vote of thanks; the Society is very grateful to Rob for the time he found in a very busy schedule to enlighten us on what happens before we turn on the gas.

Alan Haines          January 2012