But a new assessment from the US National Academies of Sciences, Engineering and Medicine says that some of these “negative emissions technologies” are ready to be deployed, on a large scale, right now.
The authors point to the fact that the US Congress has recently passed the 45Q tax rule, which gives a $50 tax credit for every tonne of CO2 that’s captured and stored. So their study highlights some technologies that are available at between $20 and $100 per tonne.
Coastal blue carbon
This report says that there is a lot of potential for increasing the amount of carbon that is stored in living plants and sediments found in the marshy lands near the sea shore and on the edges of river estuaries. They include mangroves, tidal areas and seagrass beds.
Together, these wetlands contain the highest carbon stocks per unit area of any ecosystem.
The National Academies study says that by creating new wetlands and restoring and protecting these fringe areas, there is the potential to more than double the current rate of carbon extracted from the atmosphere.
What’s more the study says that this is quite a cheap option, where carbon can be captured for around $20 a tonne.
The downsides, though, are that these coastal ecosystems are some of the most threatened areas on Earth, with an estimated 340,000 to 980,000 hectares being destroyed each year.
When you degrade these areas, instead of soaking up CO2 they themselves become significant sources of the gas.
Other problems are that rising seas around the world might swamp and destroy marsh lands. Another restriction is that there just aren’t enough coastal areas.
“Although coastal engineering is very expensive, coastal blue carbon is probably about the lowest cost option that we’ve got,” said Prof Stephen Pacala, from Princeton University, who chaired the report.
“The problem is that the total capacity is not that large.” Read More