The Australian government has agreed to invest almost $53 million in a north Tasmanian company to upgrade its coal-fired kiln so it can burn wood waste and used tires for cement manufacturing. Climate Change Minister Chris Bowen says the initiative will help decarbonize the Australian economy. Scientists disagree.
According to a report by Phys.org, the empirical evidence shows burning forest biomass to make concrete is poor climate policy, poor environmental and forest policy, and a poor use of taxpayer funds. The wood material in question includes dead trees, understory vegetation, and fallen logs — material often labeled as forest waste by industry and government.
About half of tree biomass is carbon, assuming a moisture content of 45 percent. That means burning one ton of wood generates roughly one ton of carbon dioxide emissions. Up to 30 percent of those carbon dioxide emissions remain in the atmosphere after 1,000 years.
Cement production is one of the most carbon-intensive industries in the world. About 56 percent of concrete emissions come from processing clinker, the base material for cement. Another 39 percent come from using fossil fuel to generate heat. The remaining 14 percent comes from electricity use. Governments under the Paris Agreement have been searching for alternatives to fossil fuels to power these processes, and forest biomass has increasingly been promoted as one solution, including in the United Kingdom and Europe.
But researchers point to a critical lag time between when the carbon is released and when it is reabsorbed. Carbon released instantly from burning forest biomass takes decades to centuries to be removed from the atmosphere, either through plant regrowth or by making its way to the ocean floor. That lag matters because elevated atmospheric carbon dioxide concentrations cause additional climate change in the meantime. Scientists say this is one of the key reasons why widespread burning of forest biomass in some European countries threatens their ability to meet Paris Agreement climate targets.
Material commonly called forest waste is not ecologically inert. Understory vegetation and fallen logs provide habitat for a wide range of animal species. They also play a central role in nutrient cycling and store substantial amounts of carbon. Removing them for fuel has consequences beyond the smokestack.
While trees are technically a renewable resource because they can be regrown after logging, researchers say that framing misses the point. The carbon released during burning is real and immediate. The carbon absorbed during regrowth takes generations. The gap between those two events is where the climate damage occurs.
The Tasmanian project has not yet broken ground, and the $53 million federal commitment represents a significant bet on a technology pathway that a growing body of scientific literature is calling into question.
