Mapping coal plant emissions

Mapping software can be used to bridge the gap between the science needed to understand air pollution and the engineering required to mitigate it, writes Arne Berndt

Since we began extracting and burning coal on a large scale back in the 17th century, it has proved to be both a blessing and a curse ” providing cheap energy for millions on one hand, but blighting our environment on the other.

Tackling the emissions produced through coal production is a challenge we need to rise to ” until viable energy alternatives are implemented on a wide scale ” to protect our health, our planet and our businesses,

The World Health Organization estimates that ambient (outdoor) air pollution in both cities and rural areas caused three million premature deaths worldwide in 2012 (the latest figures available), and despite some efforts, things won’t have improved since. For instance, London breached its annual air pollution limits just five days into 2017.

Emissions dispersion is important to measure
Emissions dispersion is important to measure
Credit: Soundplan

Alongside the fatalities, many millions more people are affected by respiratory diseases caused by air pollution. There is also a strong correlation between exposure to air pollution and cardiovascular diseases. At the other end of the scale, air pollution can cause temporary ailments like headaches and skin rashes.

That’s enough problems without even delving into the climate change debate.

Coal, of course, is not the only source of air pollution, but it is considered to be the most significant by some degree. Burning coal is the biggest single source of carbon dioxide emissions from human activity according to international environmental organization Greenpeace. It reports many harmful pollutants in the air from coal, which pose a serious threat to our health and environment, including issues such as smog and acid rain. The continuous nature of energy production in coal plants just adds to the problem.

A changing approach

Across the world, alternatives to coal power are being explored and developed. Along with solar and wind power initiatives, there are various trials of new batteries that can store renewable energy and increase reliability.

In China, where air pollution has become a significant public health issue in some areas, not least Beijing, they will begin turning coal plants into nuclear reactors next year, but we are a long way from reducing our reliance on coal, which is used for 44 per cent of electricity generation in the US, for example.

As coal plants are to continue, emissions need to be reduced, so it is important to fully understand where they come from and where they go following release. The source of the outputs of the plant may be largely obvious, but the dispersion after that is also important if it is to be effectively mitigated.

‘Dispersal’ refers to what happens to the pollution during and after its introduction into the atmosphere, factoring in wind conditions and atmospheric changes. Understanding this can help people identify and control it. The pollution may be visible as it leaves the plant, but it soon becomes an invisible problem, except where it forms as smog.

Personal noise-protective equipment
Personal noise-protective equipment
Credit: Soundplan

Bridging the gap

While mapping technology can’t directly reduce emissions, the ability to accurately map their sources and distribution can be invaluable, as can virtual testing of mitigation options before committing time and expense to solutions.

Mapping software can be used to bridge the gap between the science needed to understand air pollution and the engineering required to mitigate it. Air pollution dispersal is a central focus for environmental conservationists and governmental environmental protection agencies (local, state, provincial and national) in many countries as a means of air pollution control.

Accurate wide-scale measurements of air pollution are difficult to get as, even when assessed at several monitoring stations in different locations, the terrain and weather factors mean that levels can vary greatly even in small areas. Therefore, instead of relying on potentially inaccurate measurements, mapping software allows a number of models to be used to map air pollution dispersal. These range from base models to ‘simple’ Gauss models ” for approximate calculations, e.g., to estimate background concentrations or to make worst case studies, whenever free flow conditions can be assumed around emission sources ” up to complex prognostic models. The model selection depends strongly on the task and the available data.

Air pollution models are highly dependent on the meteorological situation for the dispersal calculation, requiring multiple meteorological scenarios. In order to correctly assess the pollution load for average and various percentiles, the principal concern is simulating the dispersal of the pollutants for a wide variety of wind directions and scenarios. An added variant is that the air pollutants are often reactive gases which change over time under the presence of UV light.

Critical tools

As well as looking to improve the environmental situation, the results of air pollution models are often critical in planning processes and need to be robust enough to withstand the scrutiny of the court system. It is essential that they can be validated and have well-defined boundary conditions, are supported by a team of experts and are used by well-trained people.

The management of meteorological conditions and the control of different scenarios are a constant focus for developers and software improvements regularly mean what was impossible yesterday might be possible today. Measured meteorological data must be extremely well assessed and modified very cautiously, especially if the reference meteorological station is outside the investigation area. Developers continually add tools to assess, complete and modify data.

Consequently, air pollution mapping software has become a powerful tool to save time and avoid nasty surprises when inspecting calculation results. Some software includes diagrams to analyze background pollution measurement and to deliver supporting arguments to why the background concentrations need to be adjusted.

If poor measurements cannot be rectified, this software helps visualize data problems and supplies good arguments for better data.

Once air pollution has been accurately mapped, then the software can be used to test different mitigation options, which may include carbon capture initiatives. Using the software to test in this virtual way means that all options can be tested without incurring costs and the best methods can be selected.

Noisy neighbour

Air pollution isn’t the only emission to be concerned about in coal plants. Like the vast majority of industrial premises, they are also noisy. Noise emissions are considered harmful if people are exposed to levels of 85 decibels (dB) or above for a continuous period; a sudden louder noise can also be detrimental.

Whether the impact is temporary or permanent hearing loss or other physiological or psychological effects, it can have serious repercussions for the victim(s).

Mapping software can once again help. Noise can be displayed in coloured maps, making it easy to understand the sources and propagation. They can also be produced in 3D and animated form so that the problem is truly understood. The most advanced software is sophisticated enough to map a single room or an entire country.

Using the maps in coal plants, mitigation measures, such as replacing turbine equipment with quieter models, for example, can be tested and the noise contour line established. The line is the point at which noise levels reach 85 dB and anyone crossing it should be wearing personal protective equipment, such as ear defenders.

Noise sources in coal plants vary widely in sound power, emitted frequency spectra and directivity, and also in their time dependency. Using mapping software is more effective than taking measurements as the software can break down the sources and doesn’t just work with the overall sound.

Controlling air pollution and noise emissions from coal plants is not just about being good for the environment, as important as that is. Without taking action, the health and safety of employees, visitors and local residents is threatened. As well as the personal impact, this can mean costly downtime and potentially expensive litigation. Mapping the issues and demonstrating the mitigation measures taken can help reduce those risks.

Arne Berndt is owner/adviser at SoundPLAN International, which makes noise and air pollution mapping software.

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