1 research outputs found
Assessing the Methane Emissions from Natural Gas-Fired Power Plants and Oil Refineries
Presently,
there is high uncertainty in estimates of methane (CH<sub>4</sub>)
emissions from natural gas-fired power plants (NGPP) and
oil refineries, two major end users of natural gas. Therefore, we
measured CH<sub>4</sub> and CO<sub>2</sub> emissions at three NGPPs
and three refineries using an aircraft-based mass balance technique.
Average CH<sub>4</sub> emission rates (NGPPs: 140 ± 70 kg/h;
refineries: 580 ± 220 kg/h, 95% CL) were larger than facility-reported
estimates by factors of 21–120 (NGPPs) and 11–90 (refineries).
At NGPPs, the percentage of unburned CH<sub>4</sub> emitted from stacks
(0.01–0.14%) was much lower than respective facility-scale
losses (0.10–0.42%), and CH<sub>4</sub> emissions from both
NGPPs and refineries were more strongly correlated with enhanced H<sub>2</sub>O concentrations (<i>R</i><sup>2</sup><sub>avg</sub> = 0.65) than with CO<sub>2</sub> (<i>R</i><sup>2</sup><sub>avg</sub> = 0.21), suggesting noncombustion-related equipment
as potential CH<sub>4</sub> sources. Additionally, calculated throughput-based
emission factors (EF) derived from the NGPP measurements made in this
study were, on average, a factor of 4.4 (stacks) and 42 (facility-scale)
larger than industry-used EFs. Subsequently, throughput-based EFs
for both the NGPPs and refineries were used to estimate total U.S.
emissions from these facility-types. Results indicate that NGPPs and
oil refineries may be large sources of CH<sub>4</sub> emissions and
could contribute significantly (0.61 ± 0.18 Tg CH<sub>4</sub>/yr, 95% CL) to U.S. emissions