The amount of managed oil sands CO₂ emissions, and therefore the CCS infrastructure, is very sensitive to the carbon price; significant capture and storage occurs only above 110$/tonne CO₂ in their simulations. Deployment of infrastructure is also sensitive to CO₂ capture decisions and technology, particularly the fraction of capturable CO2 from oil sands upgrading and steam generation facilities. The framework will help stakeholders and policy makers understand how CCS infrastructure, including an extensive pipeline system, can be safely and cost-effectively deployed, they suggest.

The Alberta oil sands industry is expected to rapidly expand in coming decades; production could double or more in the next 10−15 years alone. Thus, there will be an ever-increasing need to reduce the environmental impacts, in particular CO₂ emissions. This expansion means there will be many new and large CO₂ sources coming online, sources which should be integrated into an iterative, time-dependent version of our framework. In that case, the benefits of sensible planning and system-wide optimization will be even larger when compared to piecemeal unoptimized infrastructure development.

This time-dependent model would likely show interesting results, such as the early “over-building” of infrastructure like CO₂ trunk lines, in order to accommodate larger capture and storage volumes in the future. In addition, future work should account for the co-benefits associated with CO₂ utilization (e.g., EOR); EOR can reduce CO₂ management cost for early adopters of CCS as well as reduce the carbon footprint associated with conventional oil production.

—Middleton and Brandt

Their work integrated four streams of scientific research to improve understanding how the cost of CO₂ emissions mitigation varies with the size and extent of CO₂ infrastructure in the oil sands region. They developed a suite of optimal infrastructure investment plans for capturing, transporting, and injecting/storing up to 36 MtCO₂/yr from the Alberta oil sands industry.

The study is divided into four sequential steps:

• Analysis of the engineering and economics of capturing CO₂ from the oil sands industry.

• Identification of a set of spatially dispersed reservoirs capable of securely storing oil sands CO₂ emissions. These sites are characterized using a combination of existing acid gas injection data and the CO₂-PENS risk assessment model.

• Identify of a candidate network of routes where CO₂ pipelines could be constructed.

• Use of the SimCCS optimization framework to integrate CO₂ capture, storage, and transportation decisions in order to understand how the oil sands industry might respond to six different prices on CO₂ emissions.

Among their findings were that:

• At a low CO₂ price, only the most cost-effective CO₂ streams are captured, while only a relatively short pipeline network is needed to transport CO₂ to favorable storage reservoirs.

• Generally, CO₂ is first captured (1.6 MtCO₂/yr, a 4% reduction in CO₂ emissions) when the emissions price reaches $38/ tCO₂—a much higher price than Alberta’s $15/tCO₂ “tax”. Even though the capture cost is only $19.74/tCO₂, the cost to transport ($14.70/tCO₂) is high because a 488 km pipeline network is required.

• Until the emissions price reaches $62/tCO₂, no additional CO₂ is captured—i.e., it is cheaper to pay the emissions tax rather than install CCS infrastructure.

• Between the $80 and $85/tCO₂ scenarios, captured CO₂ rises from 2.4 to 9.0 MtCO₂/yr, although the network length increases only from 541 to 563 km—i.e., larger pipeline along same trunk line route. In other words, a relatively small increase ($5/tCO₂) in the CO₂ tax has a large impact on CCS infrastructure (almost four times more CO₂ captured) and CO₂ emissions in this case study; at 9.0 MtCO₂/yr, total CO₂ emissions are reduced by 23%).

• The $113/tCO₂ scenario captures 19.6 MtCO₂/yr (50% emissions reduction), while the $110/tCO₂ scenario manages 10.6 MtCO₂/yr or 27% of emissions). This large increase in captured CO₂ not only increases the network length to 758 km, the main trunk line now takes a more easterly route compared to all previous scenarios. Three new sinks are used for the first time, and one of the two sinks used in previous scenarios is no longer cost-optimal.

• Increasing the tax to just $114/tCO₂ significantly increases managed CO₂ (24.5 MtCO₂/yr, 61% emissions reduction), network length (854 km), as well as pushing the major trunk line back to the typical westerly route.

The rapid increase in captured CO₂ relative to small changes in the CO₂ price can be explained by the step function of the capturable CO₂ amounts and the extra costs incurred to transport larger amounts of CO₂. The maximum amount of captured CO₂ (i.e., 90% reduction in CO₂ emissions) is achieved when the tax rises to $155/tCO using a 1239 km pipeline network and seven storage reservoirs. At high capture rates, economies of scale in transport infrastructure are observed: instead of a web of pipelines being built, the most cost-effective system design relies on a relatively small number of large-diameter “trunk” lines that serve to move bulk CO₂ from the concentration of sources to the concentration of sinks. Even when all CO₂ emissions are captured, expensive sinks...and distant sinks...are never utilized.

The use of infrastructure optimization techniques can help the oil sands industry reduce their carbon footprint and assists policy makers and regulators in understanding how best to set a price for CO₂ emissions. Our results clearly show the benefits of building an integrated, large-scale system, rather than “one-off” pipelines between sources and sinks. Planning with foresight will aid in reducing the impacts of CO₂ emissions from oil sands operations at least cost (economically and environmentally) to society and consumers.

—Middleton and Brandt

Resources

• Richard S. Middleton and Adam R. Brandt (2012) Using Infrastructure Optimization to Reduce Greenhouse Gas Emissions from Oil Sands Extraction and Processing. Environmental Science & Technology doi: 10.1021/es3035895