Sep-2014

Driving refining change: part 2

A look at how automotive emissions legislation and the drive for energy sustainability are impacting the refining industry.

Stephen Harrison
Linde Gas

Article Summary

As the demand for sustainable fuels intensifies, there has been a marked convergence of plant science, biotechnology, crop science and petrochemical refining over the past ten years. Fossil fuels are being progressively depleted and professionals in these arenas are collaborating in the pursuit of sustainable alternative fuel sources that will reduce future dependence on traditional petroleum products.

Alternative fuels
The quest to develop fuels from other sources is being driven by geopolitics as much as it is influenced by legislation. Security of oil supply is a growing concern among countries who import massive quantities of oil for transportation fuel. A desire to establish a sustainable economic strategy by reducing expenditure on oil imports is another factor in play. So while major fuel consuming countries like China will continue to import oil from leading suppliers in Middle East, Venezuela and Brazil, there is an unprecedented trend aimed at achieving greater geopolitical self-sufficiency through the development of local biofuel production capabilities based on plant science. This trend recognises that fuel sources which harness the continuous energy of the sun to produce crops are both sustainable and cost efficient.

The current decade has heralded some dramatic changes in the fuels being used in both the automotive and aviation sectors. These biofuels are sometimes introduced to conventional fuels as additives or, in other applications, are wholly used as 100% biodiesel from rapeseed oil or other biological sources.

Finnish company Neste Oil is a leading example of a refining operation that produces biofuels and refined petroleum products derived from biological sources, notably biodiesel. A major portion of Neste Oil’s annual R&D investment goes to research into renewable raw materials and refining technologies for processing these materials. Neste Oil is involved in research involving completely new raw materials – such as microbes, algae and wood-based biomass – and existing alternatives, like waste fat from the fish processing industry. The company selects the focus of its raw material research based on availability, price and sustainability.

Neste produces NExBTL diesel, which is a hydrodeoxygenated (HDO) paraffinic fuel, as opposed to traditional transesterified biodiesel. In 2007, the entire bus fleet owned by Helsinki Region Transport switched fully to NExBTL. Experiments by Neste, VTT Technical Research Centre of Finland and Proventia showed that local emissions were decreased significantly, with particle emissions decreased by 30% and nitrogen oxide emissions by 10%, with excellent winter performance and no problems with catalytic converters. In Finland, Neste brought two renewable diesel plants, located at the Porvoo refinery, on stream in 2007 and 2009. Together, these produce 0.525 million tons annually, which is approximately one fifth of the diesel consumption in Finland. In 2010, Neste completed its third renewable diesel plant in Singapore. Producing 800,000 tons annually, it is the world’s largest renewable diesel plant. A fourth plant of the same capacity was brought on stream in Rotterdam in 2011.

Thailand’s state-owned PTT oil and gas company announced last year that it planned to develop algae biofuel in collaboration with Australia’s Commonwealth Scientific and Industrial Research Organisation. PTT plans to transfer algae knowledge back to its own research facilities and is also considering investing in algae biofuel production in Australia in the near future. Though the project development is still in its first phases PTT hopes to introduce algae biofuel into the market by 2017.

Established refineries that wish to follow the same route will need to implement technological changes focused on feedstock handling that will enable them to process agricultural products such as rapeseed oil instead of crude oil.

Methane
A stop/start driving profile is the most difficult cycle for any vehicle’s engine, resulting in production of the highest level of toxic emissions when conventional petrol or fuel is consumed. This profile is typically associated with buses and garbage collection trucks operating in urban areas and, to mitigate emissions, an increasing volume of these vehicles is now being run on Liquefied Natural Gas (LNG) or natural gas.

This natural gas, also known as “biogas” or methane, can be sourced from natural underground sources or is produced as a by-product of the waste water treatment industry, where contaminants from wastewater and household sewage, both runoff (effluents), domestic, commercial and institutional are removed from water. One of the two principle technology routes harnessed by this industry to purify water is anaerobic digestion, which is a collection of processes by which microorganisms break down biodegradable material in the absence of oxygen. Anaerobic digestion produces methane gas as a by-product, while the alternative purification technology — aerobic treatment that harnesses pure oxygen or ambient air — does not produce methane.

It’s clear that as the significance and number of applications of biogas increases, the value of natural gas will go up, prompting a shift in water treatment technology towards the anaerobic method in order to produce a by-product that has a useful economic value. This in turn will lead to a change in waste water treatment infrastructure in favour of anaerobic sludge digesters.

The handling of biogas from waste water treatment works is very similar to the handling of natural gas from other sources, since it typically remains in a gaseous form as a compressed high pressure natural gas. The gas arising from natural resources is generally converted to LNG so that it can be easily moved around the world in tankers.

Handling biogas as a source of methane presents a challenge to the refining industry because, although the same chemical is involved, the handling of a high pressure compressed gas requires different technology and different storage mechanisms in the form of high pressure cylinders, as opposed to the cryogenic technology required for LNG. Regardless of source, natural gas is poised to become an important fuel of the future, rendering the correct sourcing of technology associated with handling high pressure compressed natural gas increasingly important.

Ethanol
The properties of ethanol as a fuel for transportation are quite similar to the properties of the regular petrol currently used in today’s vehicles. Ethanol can be derived from crops such as sweetcorn, which is converted to ethanol by fermenting it in a similar process to producing beer and wine. The process removes sugars from the sweetcorn and converts them through a process of biological fermentation to produce a mixture of water and ethanol. This mixture is then distilled to produce pure ethanol, which can be added to petrol.

This process creates a strong link between agricultural science and biotechnology and brings these two worlds close to the heart of petrochemical processing and refining. In Europe today most automotive fuels contain 10% ethanol and 90% fossil fuel petrol derived from the distillation of crude oil from fossil fuels. In the USA recent legislation has allowed the use of 15% ethanol in fuel and this development foreshadows higher percentages of ethanol in fuel in the not too distant future.

Ethanol production within a refinery involves the production of the ethanol via a fermentation process, followed by the distillation of the ethanol away from water to produce pure ethanol, and finally the blending of the ethanol with conventional fuel. These are relatively new process steps and time will tell if they will be progressively incorporated into the petrochemical industry, or will lead to the establishment of factories dedicated to producing pure ethanol which will also perform the blending operation.

In a certain number of cases, instead of producing distilled ethanol from agricultural crops, refineries simply create ethanol through chemical synthesis by introducing a shift in their product mix.