Every year, air pollution kills about nine million people due to its detrimental impact on the environment and public health, particularly in urban areas. The primary sources of pollution are transportation, industrial processes, and fossil fuel combustion. The combustion of fossil fuels, particularly coal, for energy purposes, accounts for 40–50 per cent of the world’s air pollution. This causes localised air pollution and climate change (by CO2 emissions), which can result in smog, acid rain, and health problems. About 30 per cent of worldwide emissions come from the industrial sector, which also heavily contributes to acid rain and airborne particle pollution. Respiratory conditions including asthma, bronchitis, and persistent lung infections can be brought on by this pollution entering the bloodstream and lungs.
Another significant source of urban air pollution, particularly in large cities, is the transportation sector, which accounts for 15–25 per cent of all air pollution worldwide. The International Energy Agency (IEA) estimates that 24 per cent of the world’s CO2 emissions from fossil fuels come from road transportation alone. Ground-level ozone, or smog, and particle matter are major contributors to vehicle emissions, primarily from gasoline and diesel engines. These pollutants aggravate respiratory ailments.
These elements emphasise the need for tackling industrial and transportation processes, which significantly rely on fossil fuel energy sources and are the main causes of air pollution worldwide. Biofuels made from renewable resources are gaining popularity as a strategy to combat runaway pollution, lessen dependency on fossil fuels, and lessen negative effects on the environment and human health.
A type of biofuel called biodiesel has a lower environmental impact than traditional fossil fuels because of the carbon cycle that is involved in both its production and consumption. The carbon footprint of biodiesel, which is made from renewable resources like vegetable oils, animal fats, or waste cooking oil (WCO), is lowered because the plants that make it absorb CO2 during photosynthesis, which is how they develop. Biodiesel is technically carbon neutral because it releases CO2 solely to the extent that it was absorbed by the plants during their life cycle. In contrast, burning fossil fuels releases “new” CO2 into the atmosphere, which has been stored for millions of years and exacerbates climate change.
Throughout its lifecycle, biodiesel can save CO2 emissions by up to 78 per cent when compared to petroleum fuel. Biodiesel not only reduces CO2 emissions but also the production of dangerous greenhouse gases such as nitrous oxide (N2O) and methane (CH₄). In addition, it produces no sulfur emissions and emits less particulate matter and carbon monoxide (CO), making it a cleaner fuel. Moreover, spills of biodiesel break down fast because it is a non-toxic and biodegradable fuel, lowering the possibility of contaminating nearby waterways and soil.
Compared to virgin vegetable oils like soybean and canola oil, which are usually utilised in the creation of biodiesel, waste cooking oil is far less expensive. Since WCO is frequently seen as a waste product, it is available from homes, restaurants, and the food industry at little to no cost. This lowers the cost of feedstock for the manufacturing of biodiesel as well as the environmental impact of disposal. The feedstock cost can be reduced by 60–80 per cent by using WCO, which results in considerable savings.
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Steel slag, a byproduct of steel manufacturing in Basic Oxygen Furnaces (BOF), is also an underused, sustainable alternative catalyst in biodiesel production. It contains a high composition of metal oxides that are effective in the transesterification reaction. For every tonne of steel produced through the BOF method, around 0.15 to 0.20 tonnes of slag is generated, which often ends up in landfills, causing soil and water pollution. Steel slag also reduces production costs by minimising the need for purification and post-processing, thus cutting down on water usage, energy consumption, and waste disposal.
Using WCO and steel slag in biodiesel production offers a circular economy approach, turning waste materials into valuable inputs for fuel production. However, policymakers and biofuel producers must understand the complex socioeconomic and political contexts in which biofuel production will take place. For a successful transition to sustainable biofuels, Africa must pay special attention to robust policy frameworks, biofuel incentives, and consideration of socioeconomic and environmental concerns. These include gender disparities, land utilisation, raw material choices, deforestation, biodiversity, and food and energy security. My research envisages the viability of such a transition, if countries remain open to adapting and incorporating African research into bettering their climate change solutions.
Ms Ali is a PhD student in Chemical Engineering at Vaal University of Technology in South Africa, a 2023 Mawazo Fellow, and a tutorial fellow at the Technical University of Kenya