Creating Trust and Transparency in Fossil CO2 Emissions Reporting

by Jocelyn Turnbull, Senior Scientist, GNS Science

Marcus Trimble and Margaret Norris using the GNS Science high-tech grass sampling method near the Kapuni plant in Taranaki. A GPS, a plastic bag and a marker pen are all that is required. And perhaps a pair of gumboots! Photo credit: Jocelyn Turnbull, GNS Science.

Last year, I wrote about how we can use atmospheric measurements to determine whether nations and industries are meeting their fossil fuel CO₂ emission reduction goals. With the Paris Agreement, the stakes have gotten higher, with most nations agreeing to reduce their emissions, and a recognized need for “trust and transparency” amongst nations in emissions reporting.

This week, GNS Science published a new research paper taking the concepts I talked about in my previous post, and turning them into a specific method that evaluates emissions from individual power plants to better than 10% accuracy. This is key because power plants are the biggest emission sources (the huge Taichung coal-fired power plant in Taiwan produces more fossil fuel CO₂ than all of New Zealand!). This makes them an obvious target for regulating and reducing emissions. 

In the past there have been considerable barriers to measuring emissions rates from power plants. Radiocarbon measurements that need to be used in this process are time-consuming and expensive. Additionally, the atmospheric models used to translate fossil CO₂ concentration measurements to emission rates from the power plant are most accurate when averaged over long time periods.

To remove these barriers, the scientists at GNS came up with the idea of using living grass as sample collectors. There is no special field sampling equipment required, and grass effectively collects a radiocarbon sample averaged over the many days it grows. A single grass measurement tracks a week or so of emissions and is a perfect complement to the optimal model averaging period. These innovations allow us to measure the power plant emission rate to 10% accuracy. This is a marked improvement over the ~20% reported by individual power plants (based on their methods). That ~20% also doesn't take into account any bias in the plants' self-reporting. 

Grass growing in farmland near the Vector Kapuni plant in Taranaki makes an ideal sampler for fossil CO₂ emissions. Photo credit: Jocelyn Turnbull, GNS Science.

This simple and low-cost method was developed using the Kapuni processing plant in Taranaki as a test case and can be readily applied around the world.