Electric Trains: Pollution Or Progress?

Electric trains are widely considered to be environmentally friendly and a more sustainable mode of transport than cars and planes. Electric trains emit 20-35% less carbon than diesel trains and have zero emissions at the point of use. However, the generation of electricity used to power electric trains has historically relied on burning fossil fuels or coal, which produces a large amount of carbon emissions. With the emergence of clean energy generation, electric trains can now be operated with a significantly lower environmental impact. This has led to governments worldwide, including in the UK, US, and China, taking steps to electrify more railway lines to reduce carbon emissions and improve air quality, particularly in pollution hotspots such as cities and mainline stations.

Electric trains are emission-free at the point of use

While electric trains are emission-free, the means of generating the electricity used to power them is predominantly through burning fossil fuels or coal, which does produce carbon emissions. However, with the emergence of clean energy generation, electric trains can be run with a very low environmental impact. For example, the high-speed rail line proposed between San Francisco and Los Angeles in California will be powered by renewable energy sources, resulting in zero greenhouse gas emissions.

In the UK, only 41% of train tracks are electrified, and diesel trains are still heavily relied upon. In 2019, LNER retired its old fleet of diesel high-speed trains and replaced them with modern electric and bi-mode Azuma trains, reducing carbon-intensive diesel consumption by 30% compared to 2019. Similarly, the UK government has also announced plans to electrify more railways across England and Wales, which will help reduce carbon emissions.

Electric trains emit 20-35% less carbon than diesel trains, and this benefit will only improve as the electricity generation industry reduces its carbon levels. Hybrid trains, which use a combination of power sources, also reduce carbon emissions by 19%. As such, electric trains are a more environmentally friendly mode of transport than traditional cars, and they are also cheaper to run and maintain.

Rail electrification helps to reduce localised air pollution

Electric trains emit no direct carbon emissions, as they are powered by internal electric motors. However, the electricity used to power these motors often comes from burning fossil fuels or coal, which does produce carbon emissions. With the emergence of renewable energy sources, electric trains can now be powered with low-carbon alternatives, reducing their environmental impact.

Rail electrification is an important strategy for reducing carbon emissions and improving air quality. Electric trains emit 20-35% less carbon per passenger mile than diesel trains, and this benefit will only improve as the electricity generation industry reduces its carbon output. Electric trains have zero emissions at the point of use, which is particularly beneficial for improving air quality in pollution hotspots like city centres and mainline stations.

The UK's LNER successfully replaced its old fleet of diesel high-speed trains with modern electric and bi-mode Azuma trains in 2019, reducing carbon-intensive diesel consumption by 30%. Similarly, the US EPA has implemented standards for diesel locomotives that reduce particulate matter and nitrogen oxide emissions by up to 90% and 80%, respectively.

In addition to reducing carbon emissions, rail electrification can also help address environmental injustice. In the US, freight train routes often run through or parallel to communities of colour and low-income communities, exposing them to toxic diesel pollution. By electrifying these trains and improving air quality, the negative health impacts of locomotive pollution on vulnerable communities can be reduced.

Furthermore, urban and high-speed rail networks have expanded rapidly in recent years, providing convenient and low-emissions transport within and between cities. Electrified passenger rail, especially when powered by renewables or nuclear energy, has even lower emissions per passenger kilometre than other forms of transport, including air travel. As a result, promoting rail as a mode of transport can help reduce overall emissions and improve air quality, particularly in urban areas.

Electric trains are more cost-effective and cause less track damage than diesel trains

Electric trains are more cost-effective and environmentally friendly than their diesel counterparts. They have a higher power-to-weight ratio, as they don't need onboard fuel tanks, which results in faster acceleration, higher speed limits, and less noise pollution. Electric trains are also more energy-efficient, with regenerative braking reducing power loss when idling. This flexibility in primary energy sources means that electric trains can use renewable energy sources such as hydro, solar, or wind power, rather than diesel fuel.

The use of electric trains also results in less track damage. The lighter rolling stock of electric trains reduces wear and tear on the tracks, lowering maintenance costs. However, electrification of lines can increase maintenance costs due to the need for alterations or upgrades to signalling systems, and the fragility of overhead electrification systems can lead to disruptions from mechanical faults or high winds.

Despite these challenges, electric trains remain a more cost-effective and environmentally sustainable option than diesel trains. They produce less pollution, with no exposure of passengers or nearby communities to toxic diesel exhaust. The carbon footprint intensity of rail is decreasing, and the decarbonisation of the UK national grid has led to a reduction in carbon-intensive diesel consumption.

While electric trains may face some challenges regarding infrastructure and maintenance, their higher energy efficiency, reduced environmental impact, and lower track maintenance costs make them a more cost-effective and sustainable choice for rail transport.

The UK's diesel trains are breaching European air quality limits

Although rail is considered a green mode of transport compared to road and air, diesel trains emit harmful pollutants. In the European Union, diesel trains were estimated to contribute 2.0%, 2.8% and 2.5% of mobile sources for NO2, PM2.5 and PM10, respectively.

In the UK, air quality measurements have been taken at London Paddington, Birmingham New Street, Edinburgh Waverley and London King's Cross stations. The results showed that average NO2 concentrations were above the annual limit value of 40 μg m−3, with higher levels inside the stations, especially at Edinburgh Waverley. Concentrations of PM2.5 inside the stations were also elevated, up to 40% higher at Edinburgh Waverley than outside. These levels of NO2 and PM2.5 were highest near the platforms, particularly those with a higher frequency of diesel services.

UK diesel trains were found to have lower PM2.5 and PNC than other transport modes, including subway systems, diesel and petrol cars. However, the engine fuel mode was a significant factor, with NO2 levels up to 14 times higher when trains ran on diesel compared to electric or hybrid power.

To improve air quality, the UK has started replacing old diesel trains with modern electric and bi-mode trains, reducing carbon-intensive diesel consumption. Hybrid trains, such as those with a diesel engine and battery power, can reduce carbon emissions by up to 19%. Hydrogen-powered trains, or "Hydrail", are also being explored, with zero direct greenhouse gas emissions.

The US freight rail system is causing climate change and environmental injustice

The US freight rail system is one of the largest networks within a single country, with almost 140,000 route miles. While it is the most fuel-efficient way to move freight over land, it is still causing climate change and environmental injustice.

Firstly, the freight rail system emits a significant amount of carbon pollution, with diesel trains releasing the greatest amount of carbon. More than 13 million people in the US live and work near railyards, rail lines, and ports, and are directly impacted by locomotive pollution. This disproportionately affects communities of colour and lower-income communities, who commonly live and work near freight routes, bearing the brunt of toxic diesel pollution. Locomotive pollution has been linked to cancer clusters in these neighbourhoods.

Secondly, the US freight rail network is vulnerable to the impacts of climate change. Projected temperature increases pose a risk of track expansion, which can lead to train delays and, in extreme cases, derailments. To address this, freight railroads are investing in infrastructure and technology to reduce their carbon footprint and build resilience against climate change. This includes deploying battery-electric and hydrogen fuel cell locomotives, testing hybrid models, and incorporating renewable fuels. Additionally, railroads are implementing strategies to prevent wildfires, deploying "fire trains," and constructing raised tracks to minimize heat-induced track buckling.

Furthermore, the rail industry's resistance to updating pollution rules exacerbates the issue. The EPA has not updated federal locomotive pollution rules in 15 years, despite the urgent need for action. While the EPA has prioritized climate and environmental justice, the freight system still requires significant changes to address its contribution to climate change and environmental injustice.

In conclusion, while the US freight rail system is efficient in moving freight over land, it is causing climate change and environmental injustice through its carbon emissions and vulnerability to temperature increases. To mitigate these issues, freight railroads must continue to invest in sustainable practices and infrastructure, while also addressing the outdated pollution rules that have disproportionately affected marginalized communities.

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