In the absence of a global policy for nitrous oxide—a greenhouse gas with nearly 300 times the warming potential of carbon dioxide—industries have been inconsistent in deploying, affordable and readily available technologies to reduce its emissions.
The biggest source of nitrous oxide emissions is agriculture, explains the Industry Decarbonization Newsletter. They are difficult to avoid in this sector without substantial changes in farm practices.
But since the 1990s, there have been deployable and affordable options to reduce emissions in the chemical industry, another major source. Nitrous oxide emitted while producing nitric acid for fertilizers, or while producing adipic acid for nylon fibre, can be abated with two simple technologies: catalytic converters that chemically turn the gas into harmless substances, and thermal decomposition that breaks down nitrous oxide under high temperatures.
“Avoiding the equivalent of a tonne of carbon dioxide with nitrous oxide abatement technology usually costs less than five dollars,” writes Industry Decarbonization. And the costs are often below one dollar “for the easiest to avoid emissions” of a gas with 265 times the warming potential of carbon dioxide over a 100-year time scale.
In comparison, other climate mitigation technologies can be expensive. Costs between C$40 and C$140 per tonne of carbon dioxide are not unusual.
National emissions profiles reflect the benefits of abatement in countries where the gas is regulated. For instance, emissions from nitric acid have dropped from 137,000 tonnes to less than 10 tonnes in the European Union since the continent’s Emission Trading System (ETS) was implemented in 2005. And though nitrous oxide emissions from caprolactam—an organic compound used to produce synthetic fibres—are not part of the ETS, caprolactam facilities have made significant emissions reductions.
In 2015, Germany initiated the Nitric Acid Climate Action Group (NACAG), focusing on the main source of industrial nitrous oxide emissions—nitric acid production for chemical fertilizers. NACAG offers developing countries funding for the initial cost of installing abatement technologies. It has collaborated with Mexico, Uzbekistan, and Zimbabwe, and is seeking partnerships with other countries that can commit to abatement policies or regulations.
This separates NACAG from other initiatives, like the 1997 Kyoto Protocol, through which industrialized countries could use the Clean Development Mechanism (CDM) “to fund emissions reduction projects in developing countries and count those towards their own reduction goals,” explains Industry Decarbonization, adding that many of these projects happened in China.
In many cases, abatement technologies were installed with CDM funding, “only to be abandoned after funding via this instrument stopped.” As a result, China now has the world’s largest adipic acid industry where most emissions are not abated.
Abatement regulation is also inconsistent in industrialized countries like the United States, where less than half of nitric oxide facilities abate their emissions in the absence of nationwide regulation.
Nitrous oxide emissions only represent around 0.2% of global greenhouse gas emissions, but “given that only a few special processes are responsible for the bulk of these emissions, these industries proportionally have an outsized impact on climate change,” writes Industry Decarbonization. “Most importantly, due to the very low costs, these emission reduction potentials are the low-hanging fruit of emission avoidance.”