Technological advancements over the past decade have led to a rapid rise in unconventional natural gas production, known as 'shale gas', particularly in the USA and Canada. The large-scale and rapid development of shale gas has resulted in an abundant and cheap energy source, with lower direct greenhouse gas (GHG) emissions than coal and petroleum. South Africa has the eighth-largest technically recoverable shale gas reserve in the world, located in three geological formations in the Karoo; surely, then, that should be cause for celebration? But global concerns about the environmental impacts of shale gas development and production on local water supplies, air quality and human health have made the process of extracting this natural gas – called hydraulic fracturing, or 'fracking' – a very contentious issue, writes Katye Altieri.
To frack or not to frack?
The economic value of this deposit has been estimated to range from 3.3 to 10.4% of Gross Domestic Product (GDP), while estimates of the number of new jobs that could be created in its extraction varies considerably, from 1 441 to 700 000. The potential impacts on GDP and job creation in South Africa – an upper-middle income developing country with a 26.7% unemployment rate – are critical factors to consider when weighing up the pros and cons between shale gas development and environmental concerns.
A further consideration is the current power crisis in South Africa, in which the power parastatal Eskom has been unable to provide adequate electricity to match demand. Eskom is in the process of building two new coal-fired power stations, but this development is greatly at odds with South Africa's commitment to reduce GHG emissions in the coming years. Currently, natural gas contributes only 2.8% to primary energy in South Africa, and is used primarily to produce synthetic liquid fuels.
The development of shale gas in South Africa could lead to a significant shift in the electricity sector, by replacing coal-fired electricity. In addition, bridging from coal to natural gas could assist in South Africa's commitment to a peak, plateau and decline GHG emissions trajectory, as gas-fired electricity generation is compatible with energy from renewables in a way that coal and nuclear are not.
Air pollution and GHG trade-offs
However, the GHG-reduction benefits gained from shale gas are not guaranteed; neither does shale gas come without its own set of air pollution costs. Whether the costs are worth it depends largely on methane leakage rates, strict monitoring and enforcement of best practice 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.
Filling the knowledge gap
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 air pollutant 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 technologies, to the worst case, of old polluting technologies and high levels of well development.
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 second largest 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.
It is important to note that this is a prospective emissions inventory, for activities that have not commenced, and indeed may never happen. Good practice 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.
By Dr Katye Altieri, research scientist at the Energy Research Centre. Photo South African Tourism, Flickr.
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