Shale gas, air quality and GHG emissions

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. That South Africa has the eighth largest technically recoverable shale gas reserve in the world – located in three geological formations in the Karoo – should then surely be cause for celebration? Global concerns about the environmental impacts of shale gas development and production on local water supplies, air quality, and human health have however made the process of extracting this natural gas, called hydraulic fracturing (fracking), a very contentious issue.

To frack or not to frack?

The economic value of this deposit has been estimated to range from 3.3-10.4% of Gross Domestic Product (GDP), while estimates of the number of new jobs that could be created varies considerably from 1441-700 000. The potential impacts on GDP and job creation in South Africa – an upper middle-income developing country with a 29% unemployment rate – are critical factors to consider when weighing 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 the 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 primarily used to produce synthetic liquid fuels. As such, 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 renewable energy in a way that coal or nuclear is not.

Air pollution and GHG Tradeoffs

ERC participated in the Strategic Environmental Assessment for Shale Gas Development in South Africa as authors of the Air Quality and Greenhouse Gas chapter. The objective was to inform decision makers about the risks and opportunities related to shale gas development. Our chapter found that the GHG reduction benefits gained from shale gas are not guaranteed nor does shale gas come without its own set of air pollution costs. Whether or not 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. Policy makers need to formulate an air quality monitoring plan and prescribe emissions regulation levels, but they currently lack the basic information required to begin such an assessment.

A recent study conducted by ERC, and published in the journal Atmospheric Environment, seeks to fill this gap in knowledge by developing a prospective air pollutant emissions inventory for 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 minimize 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 likely 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 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 coordination 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.

Written by Katye Altieri (PhD)