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Hydrocarbon-based energy has been estimated to account for 88 percent of the primary global energy consumption in 2007. Forecast reductions in primary energy supplies are mainly due to the peaking and decline of global conventional crude oil production over the next few years. For example, production from the Western Canadian Sedimentary Basin peaked in 1998; 23 other countries have peaked since 1996 and of those, 17 peaked since 2002. Of total global production in 2007, 65 percent was derived from countries past their peak oil production. Depending on the forecasting scenario, the Alberta oil sands will delay the peak in Canadian oil production by an estimated 5 to 20 years, and contribute between 2.6 percent and 4.8 percent of the world's energy supply to meet future demands. Total bitumen production in Alberta is expected to increase from about 1.5 million barrels per day (bpd) in 2008 to about 4.3 million bpd in 2020 and, in some scenarios, is projected to reach 5 to 6 million bpd by 2030. This perceived longer-term opportunity, which was, until mid-2008, reinforced by the rapid run-up in crude oil prices, drove a dramatic acceleration in realized and planned investment in expansion of bitumen production.
New forecasts in January 2009, however, call for bitumen production to reach only 2 to 2.3 million bpd by 2020, i.e. half of what had been previously projected. The new forecast represents a reality-check for the industry and is reflective of the increased uncertainty regarding overall oil market demand and price uncertainties such as the following:
* Economic performance of traditional large-scale capital-intensive processing facilities;
* Issues surrounding local and regional environmental sustainability associated with development, including greenhouse gas (GHG) emissions and the usage of land, ecosystems, and water;
* Reformulation of finished fuel products requiring more intensive processing of bitumen-derived feedstocks.
Despite current economic issues, Alberta's oil sand reserves represent a world-scale energy resource that will play an increasingly vital role in meeting future Canadian and global energy demands. At a time when governments are spending billions to stimulate economic activity, the continued expansion and environmental viability of oil sands operations are strategically important for Alberta's and Canada's present and future economies and energy security.
Background on oil sands upgrading
Government research and development in oil sands exists to provide solutions and knowledge for addressing critical environmental issues while also ensuring their viability as a valuable resource for Canada. With the aforementioned projected increase in oil sands production, several environmental challenges concerning land, air, water, and energy conservation will need to be addressed to ensure that the development occurs in an environmentally sustainable manner. This article describes some of the research initiatives that address issues pertinent to the upgrading and refining of bitumen feedstocks.
What is petroleum refining?
Raw (unprocessed) petroleum resources contain varying amounts of hydrocarbon molecules with very high molecular weights (i.e. residue containing higher-boiling compounds) and impurities such as sulfur, nitrogen, nickel and vanadium. Due to these characteristics, neither the conventional nor unconventional petroleum resources are directly useful to industry or as transportation fuels. In order to remove the impurities and convert the higher-boiling material into useful fractions, petroleum must undergo a refining process to produce fuels, lubricants and solvents, as well as materials such as plastics, elastomers, and fibres for general use. With the gradual depletion of the world's conventional crude oil resources, and increasing prices for that commodity that we have recently experienced first-hand at retail fuel pumps, there is an ever-increasing need to process heavier feed stocks (e.g. heavy oils and bitumen] in order to help fill the widening gap between global energy supply and demand.
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Why upgrade bitumen feedstocks?
Unlike the conventional crude oil, the bitumen extracted from the oil sands needs to undergo an additional processing step before being subjected to the usual refining process. As the majority of the existing petroleum refineries are engineered to refine the conventional crude oil supplies, the bitumen cannot be processed as such in these facilities because of its higher viscosity and higher residue and impurity content. The key objective of an upgrading process is to convert the bitumen into a feedstock called synthetic crude oil (SCO), which can then be further processed in existing refineries to produce useful products.
Upgrading bitumen
A simplified schematic of a typical bitumen upgrading process is shown in Figure 1. A diluent is added to the bitumen to facilitate its transport through pipelines from the production site to an upgrading plant. The bitumen feedstock is distilled to remove the diluent and lower-boiling compounds from the "atmospheric" residue that boils above ~ 343[degrees]C. The atmospheric residue is further distilled in a vacuum distillation unit to separate the lower-boiling fractions from the "vacuum" residue, which boils above ~ 524[degrees]C. As the vacuum residue cannot be easily processed further by means of physical separation processes such as distillation, it is subjected to chemical reactions in coking and/or hydroconversion reactors. In a coking reactor, high-temperature and low-pressure conditions are used to facilitate the conversion of high-molecular-weight compounds into useful fuel fractions. These reactors reject a certain amount of carbon as solid coke. Hydroconversion processes use lower temperatures, higher pressures, hydrogen gas, and catalyst for vacuum residue processing. The various oil fractions derived from the distillation and reaction processes undergo further hydrogen addition, as well as sulfur and nitrogen removal, before being combined to form an SCO product. Synthetic crudes contain very little sulfur, nitrogen, and vacuum residue.
Research and development towards a cleaner oil sands resource
Although the steps involved in an upgrading process closely resemble those in conventional petroleum refining, the chemical and physical characteristics of bitumen pose additional processability challenges. To meet these challenges, much scientific research is being done in the areas of bitumen conversion chemistry, refinery process adaptations, and integration of current and future technologies. Technological advances will be necessary to ensure that Canada's bitumen resources remain as a competitive market choice in a world with changing environmental concerns and regulations and evolving fuel requirements. Currently, the significant challenges facing the upgrading industry are: (1) reducing GHG emissions; (2) reducing energy consumption; (3) reducing natural gas use/requirements; and (4) improving the quality of SCO. The following sections of the article discuss how researchers endeavor to provide practical made-in-Canada solutions to these challenges.
Reducing GHG emissions
GHGs trap radiant heat within the Earth's atmosphere. The GHG effect is a natural and important phenomenon of the Earth's ecosystem. Carbon dioxide, the most prevalent of all GHGs, arises from both natural and anthropogenic sources. Increases in emissions of C[O.sub.2] are considered by many scientists to be a contributing factor to the phenomenon of global warming and adverse climate changes.
The two highest GHG emitting provinces in Canada are Alberta and Ontario. The difference between these two provinces is in how the GHGs are emitted: Ontario's emissions are primarily associated with power generation, industry, and the burning of transportation fuels, whereas in Alberta the primary sources are large final emitters (LFE) such as power generation, industrial activities, and the petroleum industry, which includes oil sands operations. New upgrading facilities that are expected to come on stream in 2012 or later, may have targets based on the use of carbon capture and storage (CCS) or other technologies, in order to drastically reduce GHG emissions.
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The responsible utilization of the vast oil sands resources warrants the capture and sequestration of C[O.sub.2] for sustainable development. By far, the most significant cost in reducing C[O.sub.2] emissions arises from the capture component. Current C[O.sub.2] capture technologies available to the industry are expensive and energy intensive. Newly planned research activities at CanmetENERGY, in collaboration with scientists from various government laboratories and academic institutions in North America such as the National Institute for Nanotechnology (NINT), are aimed at developing cost-effective C[O.sub.2] capture technologies that are affordable to oil sands processors and other industries.
Adsorption processes that utilize high-surface-area solid adsorbents are less energy intensive than other methods of capturing C[O.sub.2]. However, achieving desirable adsorption and diffusion selectivity in solid adsorbents is a challenging research problem. Researchers at CanmetENERGY and NINT are planning to use quantum chemical simulations and experimental methods to develop a fundamental understanding of C[O.sub.2] adsorption by investigating the effect of pore geometries, cations, and functional groups on the C[O.sub.2] adsorption/desorption capacities and selectivities of various materials. The knowledge base derived from the research will help in the design and synthesis of nanoporous materials tailored towards C[O.sub.2] adsorption.
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