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active phases, it is important to note that these occur within a limited time frame that
is considerably shorter than the active phases of many other projects such as road
construction or the erection of a commercial building. Once the wells are completed
and brought on production, the risks from dust and smoke are significantly reduced
as most of the equipment that is the source of these emissions is no longer onsite.
Implementing mitigation measures like dust control, diesel exhaust filters, and
fuel substitution can reduce particulate emissions. Dust control for PM 10 can be as
simple as a periodic water spray on dirt roads and well pads, and the use of particulate respirators for crews working near frack sand tanks and blenders. Many O&G
wells are located in remote areas far from population centers, so broader mitigation
measures are often not used, but for drilling in urban locations where air quality
may already be compromised, mitigation is necessary.
A new technology called electric hydraulic fracturing or an e-frack uses natural
gas-fired turbines to generate electricity that powers electric pumps. The process is
much less polluting to the air than traditional diesel pump trucks and diesel generators, and also quieter for operations in urban areas. The natural gas fuel can often be
supplied essentially “for free” from nearby, existing wells owned by the production
company.
On the downside, the capital costs of e-frack equipment are approximately twice
those of diesel. Some of this may be recovered by using natural gas-fired electricity
to also supply power to the big triple rigs required to drill shale gas and tight oil
directional wells. These rigs rely on electric-hydraulic systems to lift pipe, pump
mud, and turn a drill bit. Switching from diesel pumps and generators to natural gas
turbines for well pad electrical supplies would require an up-front expenditure to
purchase the equipment, but once obtained it could be used at multiple well locations. Over time, it would substantially reduce operating expenses by substituting
natural gas for expensive diesel fuel. It would also provide much lower emissions
of PM 2.5 .
Although production operations primarily emit NOx and VOCs (described
below), the VOC emissions will form PM 2.5 from organic matter-based aerosols.
These can be a significant component of PM exposure to populations near or downwind from O&G production areas (Buonocore et al. 2019). The VOCs can also react
photochemically with the air to form ground level ozone, another health hazard.
5.2 VOCs, NOx and Fugitive Emissions
Shale gas and tight oil development activities can create measurable emissions of
volatile organic compounds (VOCs), nitrogen oxides (NOx), and methane gas
(CH 4 ). The sources of these vary from well pad to well pad (Pekney et al. 2014).
NOx is typically emitted by internal combustion engines powering generators, drill
rigs, and hydraulic fracturing pumps. Bringing natural gas, NGL, and petroleum to
the surface during the production process can release methane, carbon dioxide
(CO 2 ), and VOCs into the air from venting and flaring. Methane and VOCs may also
5 Fracking and Air Quality
active phases, it is important to note that these occur within a limited time frame that
is considerably shorter than the active phases of many other projects such as road
construction or the erection of a commercial building. Once the wells are completed
and brought on production, the risks from dust and smoke are significantly reduced
as most of the equipment that is the source of these emissions is no longer onsite.
Implementing mitigation measures like dust control, diesel exhaust filters, and
fuel substitution can reduce particulate emissions. Dust control for PM 10 can be as
simple as a periodic water spray on dirt roads and well pads, and the use of particulate respirators for crews working near frack sand tanks and blenders. Many O&G
wells are located in remote areas far from population centers, so broader mitigation
measures are often not used, but for drilling in urban locations where air quality
may already be compromised, mitigation is necessary.
A new technology called electric hydraulic fracturing or an e-frack uses natural
gas-fired turbines to generate electricity that powers electric pumps. The process is
much less polluting to the air than traditional diesel pump trucks and diesel generators, and also quieter for operations in urban areas. The natural gas fuel can often be
supplied essentially “for free” from nearby, existing wells owned by the production
company.
On the downside, the capital costs of e-frack equipment are approximately twice
those of diesel. Some of this may be recovered by using natural gas-fired electricity
to also supply power to the big triple rigs required to drill shale gas and tight oil
directional wells. These rigs rely on electric-hydraulic systems to lift pipe, pump
mud, and turn a drill bit. Switching from diesel pumps and generators to natural gas
turbines for well pad electrical supplies would require an up-front expenditure to
purchase the equipment, but once obtained it could be used at multiple well locations. Over time, it would substantially reduce operating expenses by substituting
natural gas for expensive diesel fuel. It would also provide much lower emissions
of PM 2.5 .
Although production operations primarily emit NOx and VOCs (described
below), the VOC emissions will form PM 2.5 from organic matter-based aerosols.
These can be a significant component of PM exposure to populations near or downwind from O&G production areas (Buonocore et al. 2019). The VOCs can also react
photochemically with the air to form ground level ozone, another health hazard.
5.2 VOCs, NOx and Fugitive Emissions
Shale gas and tight oil development activities can create measurable emissions of
volatile organic compounds (VOCs), nitrogen oxides (NOx), and methane gas
(CH 4 ). The sources of these vary from well pad to well pad (Pekney et al. 2014).
NOx is typically emitted by internal combustion engines powering generators, drill
rigs, and hydraulic fracturing pumps. Bringing natural gas, NGL, and petroleum to
the surface during the production process can release methane, carbon dioxide
(CO 2 ), and VOCs into the air from venting and flaring. Methane and VOCs may also
5 Fracking and Air Quality