Research & Innovation 2015-16 - Page 93

Thought leader
costs are worth it depends largely on methane leakage
rates, strict monitoring and enforcement of bestpractice regulations during fracking, and how the gas
itself is used. Shale gas exploitation requires new wells
to be drilled regularly and operate continuously, which
results in 24-hour pollution from diesel generators,
stationary engines and truck traffic transporting
water and waste to and from the well pads. The main
pollutants include nitrogen oxides (NOx), volatile organic
compounds (VOCs), and particulate matter (PM). NOx
and VOCs are precursors to ozone, which is linked
to asthma, decreased lung function and premature
mortality. Increased PM leads to increased hospital
admissions, respiratory symptoms, chronic respiratory
and cardiovascular diseases, decreased lung function
and premature mortality. However, use of shale gas
could result in considerable health benefits – despite the
air pollution – if its use displaced other, dirtier, fuels such
as coal or wood for use indoors in poorer households.
technologies, to the worst case, of old polluting
technologies and high levels of well development.
Filling the knowledge gap
It is important to note that this is a prospective
emissions inventory, for activities that have not
commenced, and indeed may never happen. Goodpractice guidelines will be needed to minimise
impacts on air quality and reduce GHG emissions,
with guidelines for control technologies, consideration
of effective legal regulation, early establishment
of baselines, and continuous monitoring and good
governance enabled by co-ordination across several
South African institutions – a challenging set of tasks.
The literature on shale gas development is largely
international, particularly from the USA, with relatively
few studies undertaken in South Africa. This partly
reflects different levels of development of shale gas,
but points to the overall need for more research,
including on air quality and GHG risks under South
African conditions.
The Karoo is a sparsely populated and vast area
with low levels of industrial activity. Before shale gas
exploration occurs in South Africa, it is important
to investigate the potential negative impacts on air
quality in the Karoo, as well as the potential benefits
for GHG emissions for South Africa as a whole.
Policymakers need to formulate an air-quality
monitoring plan, and prescribe emissions regulation
levels; but currently, they lack the basic information
required to begin such an assessment.
A recent study conducted with my colleague,
Adrian Stone, and published in the journal
Atmospheric Environment, seeks to fill this gap
in knowledge by developing a prospective airpollutant emissions inventory for the NOx, PM and
VOCs associated with all aspects of shale gas.
Emissions inventories can be used to establish
regulations, devise enforcement strategies and
health-risk assessments, as a predictive tool to
establish monitoring strategies and as inputs to
regional air-quality models.
The amount of air pollution that results from shale
gas depends on the number of wells drilled, as
well as the technology used. We constructed a
well-development model for South Africa, using
information from existing well fields in the USA
and what is known about the scale of the Karoo
shale gas field. A wide range of technologies were
assumed to be possible, from old engines (e.g.
those available from mining operations), which
could lead to high pollutant emissions, to newer
electric engines, which would minimise air pollutant
emissions. All of the uncertainty was included in
the emissions calculations, such that a range of
emissions is determined – from the best case, of
very controlled resource exploitation using clean
Prospective impact of shale gas on air quality
We find that the shale gas industry will probably
become the largest regional source of NOx and VOCs
(bearing in mind the current under-development of
the region), comparable to adding a city the size of
Durban to the middle of the Karoo. Even if the lowest
estimate of NOx emissions is used, shale gas would be
the fourth-largest source of NOx nationally. Similarly,
VOCs from shale gas activities would be the secondlargest source of VOCs in the country. The high
estimated values of NOx and VOC emissions are a
concern, for regional ozone and for compliance with
national ambient air-quality standards. But emissions
could be reduced, even with large-scale development,
using already existing control technologies.
Renewable energy is available as nature provides it,
not as a function of electricity demand. Therefore,
demand and supply cannot always be matched.
Natural gas electricity-generation plants respond
to demand very rapidly compared to both coal
and nuclear, which provide baseload electricity.
Baseload plants can take several days to start
up and shut down; and they run all of the time,
providing a continuous level of energy. Natural gas
peaking plants are smaller and can respond rapidly
to changes in supply and demand. Thus, natural
gas is quite compatible with renewable energy, as
it fills the gaps in supply created by variable wind
and sun.
By Dr Katye Altieri, research scientist at the
Energy Research Centre. Image by South African
Tourism, Flickr.
Affordable, clean energy and climate action 88


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