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As the world population has just passed the seven billion mark, there will be a proportional increase in global energy demands. In 2011 the International Energy Agency (IEA) projected a significant increase in global energy demand by 2050. Although conventional energy sources will play a vital role towards satisfying this demand, sustaining it longer term will require capital investment in unconventional sources of energy such as oil sands.
Background
Oil sands, also known as tar sand, are porous carbonate earth materials enriched with heavy asphaltic crude oil known as bitumen. The world’s largest amount of oil sand deposit is found in Alberta, Canada.
In this region, three major oil sand deposits have been identified and they include the Athabasca, Peace River and Cold Lake deposits. These deposits account for 169 billion barrels of oil reserve (Energy Resources Conservation Board, 2011) and occupy an area larger than the state of Florida (Oil Sands Consultations 2007). The extraction and upgrade of bitumen from the oil sand reserve is very energy intensive due to the high viscosity of the product, which must be diluted or heated to allow flow or pumping. As a result of the energy intensity, the process contributes significantly to atmospheric deposition.
One of the major processes involved in the production of unconventional energy is the recovery of bitumen from the oil sands’ deposits. Over the years, the techniques used for bitumen recovery have been subject to technological metamorphoses, resulting in less energy intensive techniques. Currently, bitumen deposits in the oil sands can be recovered through surface mining or drilling (in-situ recovery) using Steam Assisted Gravity Drainage (SAGD) techniques. The depth of the reserve determines the method of recovery used, and consequently, the environmental footprint.
Surface mining of bitumen, used for shallow deposits of between 70-100m depths, requires the clearing and excavation of a large area of intact forest. The total land disturbance perpetrated by this technique leaves a colossal environmental footprint. On the other hand, in-situ recovery involves drilling wells into deposits typically deeper than 100m and injecting steam into the reservoir, reducing the viscosity of bitumen, and allowing it to be pumped to the surface.
Generally, the production and consumption of oil sands are coupled with the emission of greenhouse gases (GHG) and air pollutants such as carbon dioxide (CO2), ozone (O3), hydrogen sulphide (H2S), nitrogen oxide (NOx), sulphur dioxide (SO2) and fine particulate matter to the atmosphere. The generalisation of emission sources has created some gaps in the oil sand emission inventories, however – especially with regards to GHG emissions from associated land use change. The contribution of the latter to GHG emission cannot be neglected, because of relatively high amounts of carbon stock lost through oil sand land use (Yeh et al, 2010).
For instance, surface mining involves the draining and excavation of peatlands, a type of wetland with the ability to sequester CO2 from the atmosphere. Consequently, the drained and/or extracted peat will begin to decompose, releasing GHGs such as CO2, CH4 and NOx into the atmosphere. The current oil sand emission inventories do not account for these emissions and these might have led to the underestimation of GHG emissions from oil sand activities.
This article describes the current practises in oil sand GHG inventory, identifies the contribution of oil sand land use to GHG emission and highlights the practises that can help achieve a detailed oil sand land use GHG inventory.
Why is GHG emission monitoring essential?
Monitoring atmospheric GHG emission is essential in the oil sands because the components of the atmosphere provide protective cover to the biosphere. Under pristine conditions, a balanced feedback mechanism is established through atmosphere-biosphere interactions.
Emission of GHGs through industrial activities influences the composition of the atmosphere, causing an imbalance which affects ecosystems and human health. A good example of such impacts on ecosystem health is the loss of sensitive vegetation species, e.g. Sphagnum Mosses, in the moorlands within the Peak District National Park following the deposition of sulphur from coal mining operations during the industrialisation of Northern England (Caporn et al, 2007).
Similar trends ensuing from oil sand activities are addressed in subsequent sections of this article. The information from GHG emission monitoring is essential for linking emission sources to its impacts on biosphere functions. The measurements made will provide a baseline for current emissions, enable prediction of future trends and extend the trends back in time to past conditions.
GHG emission from Alberta’s oil sands
The climate change impacts of GHG emissions are shared global challenges that are independent of emission source. Canada has demonstrated her commitment to reducing GHG emission by signing the Copenhagen Accord, which requires that GHG emissions are reduced by 17% below 2005 levels by 2020. While accounting for 0.5% of the increasing world population, Canada produces 2% of global GHG emission and 6.9% of this comes from oil sands. The latter implies that the Alberta oil sands which produced 48 megatonnes of GHG in 2010, accounts for just 0.16% of global GHG emission (Environment Canada, 2012). From the 1990s until the present, GHG emissions associated with oil sand production have seen a 26% reduction due to technological advancements.
Alberta is the first North American jurisdiction to implement mandatory GHG emission reduction targets. In 2007, the government of Alberta implemented a GHG regulation, requiring facilities that emit more than 100,000 tonnes of GHG emissions a year to reduce their emissions’ intensity by 12%, or payment in lieu. The latter allows companies which are unable to comply with the target through direct emissions’ reductions to use recognised offsets by paying a C $15 per tonne fee into a clean energy technology fund.
Records indicate that this fund has generated about C $200 million that is being invested into innovative technologies and projects that will reduce GHG emissions. According to Alberta Environment and Sustainable Resource Development (AESRD), since implementation in July 2007, these regulations have resulted in GHG reductions of more than 23 megatonnes, the equivalent of taking 4.8 million cars off the road for one year. Notwithstanding the recorded success in GHG emissions’ reduction from the oil sands, a major concern is to assess if these GHG statistics presented above are from detailed emission source inventories.
GHG inventory in the oil sands
Environment Canada, (2012) reported that in the past, data resulting from monitoring of emissions are often not incorporated into air emission inventories. Instead, approved emission rates are used, e.g. the rate at which the facility is permitted to emit. In the absence of approval limits or emissions’ monitoring data, the general approach is to use emission factors coupled with source operational or activity data to estimate the emissions from various sources. Together, these factors limit the value of existing inventories for determining effects of present and future emissions on air quality. This explains why GHG inventories from the oil sands often focus on life cycle assessments.
Life cycle GHG assessment involves measuring total GHG emissions from the start of oil sand production through to combustion – from well to wheel. Under this system, GHG emission inventories tend to adapt a holistic approach. The generalisation of emission sources has led to the omission of critical emission sources that can only be captured through fine scale measurements. For instance, the GHG emissions resulting from the land use change penetrated by the draining of peatlands before the recovery of oil sands are not considered under the life cycle analysis approach.
The gaps in emission data inventories were identified in a recent report by Environment Canada, (2012) on an integrated air quality monitoring plan for the oil sands. The report recommended a breakdown of existing holistic emission sources so as to provide a scientific emission inventory that adequately represents the individual emission sources.
The report identified five sources – stack emission, mobile emission, fugitive emission, community and natural sources – which are critical to achieving a detailed emission inventory. Under fugitive emissions mine reclamation was listed as one of the missing emission sources that is required to complement the scientific emission inventory.
With regards to GHG emission sources associated with oil sand land use, however, peatland draining and decomposition present a greater potential for being critical emission sources than mine reclamation. Still, this has not been duly addressed in the new scientific emission inventory. To overcome this limitation, scientific emission inventory needs to consider all the emissions associated with oil sand land use change and those from subsequent feedbacks.
GHG emission from oil sands land use change
The United Nations Climate Change Secretariat defined land use change as “a GHG inventory sector that accounts for emissions and removals of greenhouse gases resulting from direct human-induced modification of natural land use capabilities.” For instance, the conversion of Boreal forest wetlands to open pits and tailing ponds after oil sands’ mining is a major form of anthropogenic land use change.
Land use change is usually associated with a change in land cover and a consequent change in ecosystem carbon stock. The intensity of GHG emission from any land use change depends on the amount of carbon stored in the ecosystem prior to disturbance.
Canadian oil sand projects are mainly located in Northeastern Alberta, with some development extending to the northwest of the province and east into Saskatchewan, an area classified as the Boreal forest region (Alberta Sustainable Resource Development, 2007). Historically, the Canadian Boreal forest regions were largely intact and undisturbed, an area described by Graf, (2009) as one of the largest pristine ecosystems on the planet.
About 50% of the Boreal forest landscapes are dominated by wetlands, and peatlands account for about 90% of these wetland types (Vitt et al, 1996). These peatlands have accumulated large carbon stocks since the last glaciation due to the imbalance between the rate of biomass production and decomposition driven by low temperatures and high water levels (Vitt, 1994). Peatlands represent the largest stock of carbon among other Canadian terrestrial biome, thus play a key role in the regional and global carbon cycle (Gorham, 1991).
The carbon sink function of peatlands is undermined by oil sands’ land use change. A good instance of GHG emissions from peatland disturbance (land use change) is seen in the work of Page et al (2011) in the palm oil producing regions of Southeast Asia, where peatlands are being drained to increase palm oil production for the growing global market. Unlike the oil sand development region, however, GHG emission inventory in Southeast Asia considers the land use change associated with peatlands’ exploitation for unsustainable palm oil production as a major source of GHG emission within the region.
The first stage of oil sand recovery involves the draining of peatlands, overlaying the deposit and stripping of surface vegetation cover. By removing the functional vegetation layer on the surface of a peatland, the disturbed ecosystem loses its inherent ability to sequester atmospheric carbon (CO2) through photosynthesis.
In addition, the draining of peatlands creates suitable conditions for the decomposition of belowground organic carbon stock (Turetsky et al, 2002). On decomposition, the carbon stored in peatlands will be released back into the atmosphere as either carbon dioxide or methane (CH4), depending on antecedent soil moisture conditions. These gases – CH4 and CO2 – that are released during peat decomposition have been implicated due to their global warming potential (IPCC, 2007).
As oil sand developments on peatlands continue to extend to an area of about 1,400 km2 (Alberta Environment, 1999), the rate of GHG emissions from associated land use change will likely increase. Although Yeh et al (2010) have conducted a preliminary study on land use GHG emission from Alberta oil sands, there is need for more research attention in this area. Such research is not only required for improved scientific GHG emission inventory, but also to help understand the direct and indirect feedbacks resulting from increasing trends in land use change and GHG emission in the oil sands’ development region.
Feedbacks associated with oil sand land use change
The closely coupled interaction existing among the various components of the biosphere results in a feedback mechanism. For this reason, a functional change in any of the biosphere components is reflected in the other components. A good example of this feedback is evident in the interaction between the soil, vegetation and atmosphere following land use change.
The carbon released into the atmosphere through peatland draining and decomposition contributes to increasing CO2 concentration locally. Some studies have suggested that under high CO2 concentrations, the rate of photosynthesis will increase in some plant species, allowing them to remove more carbon from the atmosphere. This is referred to as the carbon fertilisation effect (Houghton et al, 2000).
In the vicinity of the oil sands’ development, the CO2 fertilisation effect will be enhanced by nitrogen deposition, which is eminent in this area due to NOx atmospheric pollution from anthropogenic activities (Bhatti et al, 2003). In adjacent intact peatland ecosystems, a blend of these CO2 and NOx fertilisation effects will reduce vegetation biodiversity by encouraging the growth of deciduous, or broadleaf trees at the expense of peatland species such as Sphagnum Mosses – the major builders of peatland carbon stock.
This structural transformation of peatlands to a forest-like ecosystem affects the global carbon cycle in two major ways. Firstly, by increasing the density of broadleaf trees in this region, the risk and frequency of forest fire will increase, especially under projected drier climate conditions. Forest fire is a major natural disturbance and a source of air pollution/GHG emission in the Boreal forest region (Turetsky and St Louis, 2006). When a forest burns, the carbon and nitrogen compounds stored in biomass are released back into the atmosphere as GHGs with other air pollutants and fine particulate matter.
Secondly, compared to peatland ecosystems, the rate of carbon turnover in deciduous forest is very high as a result of the high decomposition rates, stimulated by low C/N ratio of broadleaf vegetation. Under increasing NOx fertilisation, the vegetative parts of deciduous plants are structurally composed of simple carbohydrate compounds, which are less recalcitrant to microbial degradation. Faster rates of biomass decomposition have an implication on the carbon cycle and GHG emission.
Accounting for oil sands’ land use GHG emissions
The preceding sections of this article highlight the significant contributions of oil sands’ land use change to GHG emissions. The feedback mechanisms ensuing from oil sands’ land use change further highlight the need to consider it as a major source of GHG when taking a scientific GHG emission inventory for oil sands.
This is critical in the case of the Alberta oil sands’ industry, where land use GHG emissions’ intensity is very high due to the carbon richness of the region’s landscapes (Yeh et al, 2010). Achieving a high quality inventory for land use GHG emission will require adequate forest carbon stock quantification prior to implementing any sort of land use change. This can be achieved by a combination of different methods used in carbon stock measurements (Gibbs et al, 2007). Following land disturbance, e.g. draining of wetlands, meteorological instrumentation can be implemented in-situ, to monitor the contribution of the disturbed area to GHG emission.
Based on a review of the IPCC 2006 guidelines, the World Resources Institute identified the following four main methods for GHG emission quantification: the emission factor-based method; the mass balance method; the predictive emissions monitoring system (PEMS) and the continuing emissions monitoring system (CEMS). The method used depends on the purpose and scale of GHGs quantification.
In the Boreal forest regions, the eddy covariance technique is widely used to explore the continuous exchange of GHGs between peatland ecosystems and the atmosphere. For unforeseen GHG emission sources, e.g. wild fire during the fire season, fluxes of GHGs from forest fires can be quantified by installing eddy towers on adjacent landscapes that are not classified as fire risk areas.
With high footprint resolution, such installation could capture the fluxes of GHGs from any accidental forest fire event. This will help improve the quality of oil sands’ GHG inventories by accounting for indirect sources of oil sand land use GHG emissions.
Conclusion
The studies reviewed in this article suggest that unconventional oil sands’ production will play a key role in satisfying the growing global energy demand. Thus, increase in the price of oil and technological advancement will drive a proportional increase in oil sands’ development activities.
As development expands across the oil sand region – an area larger than the state of Florida – the GHG emissions associated with such large scale land use change will make an enormous contribution to the regional GHG emission inventory. Notwithstanding the anticipated impact, the current oil sands GHG emission inventories have focused on emissions from upgrader fire, flare use, highway and non-road mining fleets – life cycle assessment – and more recently fugitive emissions.
Most of the GHG emissions associated with land use change are classified as fugitive emission. Such a generalisation is misleading and tantamount to underestimation of land use change impacts on GHG emissions. Thus, this article identifies the need for fine-scale emission inventories that will use multi-source monitoring to develop a high resolution and comprehensive inventory. This article also suggested possibilities for estimating GHG emissions from indirect sources of oil sands land use emissions, to help improve future oil sands’ GHG inventories.
Published: 27th Nov 2012 in AWE International
