Air pollution from the combustion of fossil fuels is creating an ongoing global public health crisis. Data from the World Health Organization (WHO) illustrates that ambient air pollution caused ~4.2 million premature deaths worldwide in 2019 with almost 89% of those in low- and middle income countries.  

Climate change, one of the most significant environmental challenges of our time, is driving the global transition to clean energy. As we address this global challenge, we have the opportunity not only to reduce carbon emissions, but to improve air quality in communities worldwide which currently experience the worst fossil fuel pollution.    

Large fossil-fuelled power stations and motor vehicles are commonly blamed for air pollution, but often-overlooked are the polluting diesel generators which tend to be located in populated areas. In many developing countries, the unpredictability of the grid necessitates the use of these diesel generators to ensure reliable, resilient power, regardless of their high cost and the toxic pollutants they emit.  

Despite their drawbacks, these diesel generators are a critical electricity source for millions of homes and businesses. Fortunately, clean energy technologies are now available which can replace these dirty diesel generators and provide clean, reliable energy 24/7. New battery technologies, such as the iron flow batteries manufactured by ESS, can be deployed either as standalone backup systems or incorporated into community-scale solar + storage microgrids to replace backup diesel generation and ensure clean air.  

Dirty Diesel  

There are estimated to be 82.6 millions diesel generators in use globally. In the developing world, these generators provide an estimated 350–500 gigawatts (GW) of energy across 20-30 million individual sites, permeating communities worldwide.  

This generation capacity is equivalent to hundreds of coal power stations. But, while large central power stations are typically located in remote areas, diesel generators are found in urban areas where their particulate, nitrogen oxide, and carbon monoxide pollution is particularly harmful to local communities.   

While particularly acute in the developing world, developed economies do not fully avoid the impacts of diesel generators either: industry relies on diesel generators for construction, off-grid applications (such as agriculture),and as back-up power for critical infrastructure such as hospitals and data centres.  

A recent study by the Centre for Science and Environment provides one example in a community in India where diesel generators operated several hours a day increased particulate matter (PM) such as PM2.5 and PM10 by 30% and 50-100% compared to levels before their operation. (PM2.5 and PM10 refer to inhalable particles in the air measuring 2.5 and 10 micrometres in diameter, respectively.) PM2.5 poses the most critical threat to human health. These particles can affect an individual’s lungs and heart and have been linked to heart disease, asthma and reduced lung function. Particulates can also affect water and soil quality, and damage sensitive forests and farm crops.  

A report on London air pollution stated that 26% of the PM2.5 and 40% of the PM10 from diesel fuel combustion comes from construction, industrial and commercial applications, not automobiles. In California, their emissions are estimated to cost $136 million in annual health costs, underscoring the global nature of the risk.  

Sun, Wind and Long-duration Energy Storage Offer a Path Forward  
The ultimate answer is clearly to transition to renewable energy sources which emit little or no pollution. Replacing a fossil-fuel generator with solar and wind power will limit particulates almost immediately while also quickly reducing or eliminating other pollutants in ambient air. 

The transition is not without challenges. As renewable energy is increasingly deployed to the grid, it is becoming clear that the intermittency of wind and solar remains a challenge to reliability and grid stability. Today, if the sun is not shining or the wind is not blowing, diesel gensets are needed to fill the gap in many places.  “Green” datacentres that are designed to be powered exclusively by renewables are forced to depend on diesel generators for back-up. Amazon Web Services recently announced that it was purchasing over 100 diesel generators, and that is just for its datacentres in Ireland.  

To realise the benefits of renewables, clean energy sources will need to be coupled with energy storage to provide reliable, resilient energy and avoid the need for diesel generation.  Emerging long-duration energy storage technologies can store and deploy hours of clean energy and enable renewable energy to be available on demand. For example, ESS iron flow batteries provide up to 12 hours of energy storage. In addition, they are safe and nontoxic, and can be safely sited in populated areas, providing safe, clean energy whenever needed.