Life Cycle Greenhouse Gas Emissions of Current Oil Sands Technologies: Surface Mining and In Situ Applications

Abstract

Life cycle greenhouse gas (GHG) emissions associated with two major recovery and extraction processes currently utilized in Alberta's oil sands, surface mining and in situ, are quantified. Process modules are developed and integrated into a life cycle model-GHOST (GreenHouse gas emissions of current Oil Sands Technologies) developed in prior work. Recovery and extraction of bitumen through surface mining and in situ processes result in 3-9 and 9-16 g CO(2)eq/MJ bitumen, respectively; upgrading emissions are an additional 6-17 g CO(2)eq/MJ synthetic crude oil (SCO) (all results are on a HHV basis). Although a high degree of variability exists in well-to-wheel emissions due to differences in technologies employed, operating conditions, and product characteristics, the surface mining dilbit and the in situ SCO pathways have the lowest and highest emissions, 88 and 120 g CO(2)eq/MJ reformulated gasoline. Through the use of improved data obtained from operating oil sands projects, we present ranges of emissions that overlap with emissions in literature for conventional crude oil. An increased focus is recommended in policy discussions on understanding interproject variability of emissions of both oil sands and conventional crudes, as this has not been adequately represented in previous studies.

Energy consumption and greenhouse gas emissions in the recovery and extraction of crude bitumen from Canada’s oil sands

“…The figures in the literature for electricity consumption in surface mining unit operations vary widely. Bergerson et al reports 50-100 kW h of electricity consumption per m 3 bitumen [24]. A feasibility study of a stand-alone surface mining project estimates 34 kW h of electricity consumption per m 3 of bitumen [34].…”

“…Brandt suggested further research toward modeling the emissions of process-specific configurations. Bergerson et al [24] documents the development of GHOST, a life cycle assessment model for oil sands-derived pathways. GHOST is based on confidential data from industry on energy consumption from a set of operating projects.…”

“…(a)[21] Emissions are calculated based on default values of fuel consumption specified in the model; (b)[20] Emissions are calculated based on default values of fuel consumption specified in the model; (c)[10] The lower value is with cogeneration and the higher value corresponds to the ''no cogeneration'' case. The emissions reported are based on the assumption that energy in surface mining is about one half of the energy consumed in SAGD operation with SOR of three; (d)[24] The ''no cogeneration'' and ''with cogeneration'' ranges overlap; the range shown is a combined range; (e) Values reported in the literature have been converted using 8 API gravity and LHV of bitumen from the GHGenius, for comparison purposes.…”

Process analysis of a low emissions hydrogen and steam generation technology for oil sands operations

“…The hydrogen product stream (4) is cooled in a heat exchanger (B7) where its energy supplies the sensible heat for heating the NG feed (NG-1) from 15°C to 1,000°C. The cooled hydrogen stream (12) is fed to a pressure swing adsorption (PSA) column where the hydrogen product (6) is separated from impurities (5). The heat requirements of the NGD reactor are supplied by the oxy-fired NG combustor (B10), which are fed NG (NG-2) and oxygen (O2).…”

“…To ensure compliance to this policy, the oil sands industry must reduce the energy intensity of bitumen extraction and upgrading or pay into a technology fund at CAD$15/tonne CO 2 emitted. To put the life cycle GHG footprint of heavy oil recovery in perspective, production of SCO results in emissions ranging from 99 to 176 kg CO 2 eq per barrel (bbl) (1 bbl = 0.156 m 3 ) of oil or 16.2-28.7 g CO 2 eq/MJ whereas conventional crude oil production emits 27-58 kg CO 2 eq/bbl (4.5-9.6 g CO 2 eq/MJ) [4][5][6]. By implication, a facility producing 30,000 bbl/d oil from an oil sands process emits about 1.8 million tons/yr GHGs and is expected to make an annual GHG reduction of 251,400 tons CO 2 -eq or pay $3.2 million/yr carbon tax.…”