In the 10 years 1996-2005, US refiners significantly reduced the amount of hazardous air emissions, according to a September 2008 report from the US Environmental Protection Agency.
The report “2008 Sector Performance Report” said that, in 2005, US refiners reported 42.2 million lb of absolute air emissions to EPA’s annual Toxics Release Inventory (TRI). This was a 31% decrease from the level in 1996, which was 61.1 million lb.
TRI chemicals in water discharges, however, increased during the reporting period.
The total amount of waste managed decreased during 1996-2005.
Air emissions
In 2005, 163 refineries reported they emitted 18.9 million lb less air pollutants than in 1996, a reduction of 31% (Fig. 1).
These emissions of all TRI chemicals include hazardous air pollutants (HAPs) regulated under the Clean Air Act.
HAP emissions during 1996-2005 declined to 19.4 million lb from 36.0 million lb.
When normalized by crude inputs to the refineries, air emissions decreased by 36% during the reporting period (Fig. 2). The emissions of HAPs normalized for crude inputs decreased 50%, to 18.1 million lb.
EPA’s report also assigned a risk-screening environmental indicator to each TRI chemical to consider the relative toxicity of air emissions.
The normalized toxicity score for US refiners increased by 50% during 1996-2005.
The toxicity score increased mainly due to sulfuric acid, which has a relatively high weighting compared with other TRI chemicals and is related to SO2 emissions. Sulfuric acid accounted for about three quarters of the 2005 toxicity score.
Ammonia was the most emitted chemical in 2005, accounting for 8.574 million lb. Sulfuric acid was the next highest-ranked chemical with 8.015 million lb emitted in 2005.
Greenhouse gases
The report stated that, in terms of methane emissions, US refiners released an estimated 28.4 million tonnes of CO2 equivalent in 2005. This was an increase of 7% since 1996.
Vented emissions accounted for 87% of greenhouse gas emissions. Fugitive and combustion emissions accounted for 6% and 7% of emissions, respectively.
Water discharges
The EPA report stated that in 2005, 121 US refineries reported water discharges of 17.7 million lb of TRI chemicals. This amount was an absolute increase of 52% compared with 1996 and a normalized increase of 42%.
Nitrate compounds and ammonia accounted for 97% of the reported discharges.
Waste management
According to the report, refiners reported generating 5.1 million tons of hazardous waste in 2005. The hazardous-waste management method that refiners used most was disposal, which accounted for 84% of wastes managed.
In 2005, refineries reported 1 billion lb of chemicals released, disposed, or managed through treatment, energy recovery, or recycling. This was a 22% decrease in waste managed compared with 1996, when normalized by crude inputs.
In 2005, 54% of managed waste was treated, 23% was recovered for energy use, 17% was recycled, and 6% of TRI-reported waste was disposed or released. Energy recovery was the main waste management method in the late 1990s; treatment, however, is now the primary management method.
Refiners reported disposing of 6.3 million lb of TRI chemicals to land or transferred to offsite locations for disposal in 2005. Ammonia, zinc, and nickel accounted for nearly half of the total weight of chemicals disposed. Most refinery TRI hazardous waste disposals used underground injection, although 43% relied upon landfill disposal.
