Reducing nitrogen oxides makes the air cleaner to breathe

03 February 2021, 14:33 EET

The focus in solving the current climate crisis is on reducing CO2 emission levels and moving towards a low-carbon economy – and fast. Yet, at the same time, we need to continue controlling the discharge of other harmful emissions, such as nitrogen oxides, into the environment, as they have serious environmental and health impacts.

Cows on a meadow in front of a power plant.

NOx emissions occur when nitrogen oxides, a chemical compound of oxygen and nitrogen, are released as a gas into the atmosphere during combustion at high temperatures. This happens mainly from the combustion of fossil fuels, such as oil, diesel, gas and organic matter. Nitrogen oxide pollution in urban areas is primarily caused by traffic, but also by energy production. Nitrogen oxides are also produced naturally by volcanic outbursts and lightning. However, the emissions caused by human activity are clearly more harmful, due to high local concentration.

Why should we control NOx emissions?

NOx emissions cause a range of harmful impacts on human health and the environment. The emissions are responsible for smog and the typical brown cloud formation that commonly covers larger cities, causing poor air quality that can lead to respiratory problems and headaches. NOx emissions irritate and, at high concentrations, damage respiratory tissues and blood vessels, and they also increase the risk of cardiac disorders.

Nitrogen oxides also contribute to acid rain and the formation of ground-level ozone, which can adversely impact plant life by damaging foliage, decreasing growth or reducing crop yields. NOx deposition in the oceans provides phytoplankton with nutrients, leading to harmful algae blooms.

The EU strictly regulates emissions to air

Countries around the world have adopted regulations that require energy producers and industrial operators to reduce their NOx emissions. Among others, the EU has set very strict limits for flue-gas emissions. The graphic below illustrates the steps the EU has taken over the past 30 years to tighten the allowed limits for NOx emissions.

IIPC = International Plant Protection Convention
LCP = Large Combustion Plants
IED = Industrial Emissions Directive
BAT / LCP BREF = Best Available Technology / Reference Document on BAT techniques for LCP​​


Emission limits became stricter when the Industrial Emissions Directive (IED) came into force in 2016; the EU is expected to again tighten the allowed emission limits for large industrial installations in 2021. The regulatory path that the EU has taken thus far in reducing emissions is expected to be followed by others, and the global trend towards continuously lower emission limits is likely to continue.

Clean air is a major priority

Clean air is essential to human health and wellbeing as well as to the surrounding environment. According to a survey*, 88% of respondents prioritised clean air as their top personal concern.

*) BBMG and Sustainable Brand: Unleashing the Power of Brands to Create a Culture of Sustainable Living. 2020.

Nordic cities less polluted

According to a recent urban health study** that ranked European cities based on premature mortality rate due to air pollution, the Nordic cities revealed to have the lowest risk for death resulting from nitrogen dioxide (No2) emissions.

**) ISGlobal Ranking of Cities, led by the Barcelona Institute for Global Health

Cutting NOx emissions in energy production is feasible

In energy production, it is possible to decrease nitrogen oxide and other harmful air emissions through the choice of fuel and combustion technology, and with various flue-gas cleaning technologies. As Fortum aims to reduce emissions to air from its own operations, it also offers its own solution for the efficient reduction of NOx emissions through advanced combustion technology.

All Fortum's power plants operate in compliance with the terms of their environmental permits, and, for the most part, its plants also meet the new emissions requirements in Europe. Emissions at Fortum's Russian power plants are limited in accordance with Russian legislation.

Fortum’s solution reduces NOx emissions effectively by preventing the formation of NOx in the combustion process. Compared to alternative methods, Fortum’s solution is cost-efficient and environmentally friendly, as there is minimal need for new equipment, no auxiliary power consumption, no water consumption, and no ammonia or urea consumption, meaning no by-products requiring disposal.

Since the 1990s, Fortum has implemented approximately 50 projects to reduce the nitrogen oxide emissions of our customers’ coal- and oil-fired boilers in the EU area and, recently, also in India. Cumulatively, we have reduced NOx emissions at our customers' power plants by more than 800,000 tonnes globally. By comparison, Finland's total NOx emissions were 130,000 tonnes in 2017.

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