Remoorestation: recreating peatlands with hydrochar
Reforestation is a major component of most carbon capture strategies. But how about bringing back peatlands?
Peatlands, coming in a variety of forms such as moors, bogs, (quag)mires, muskegs, or fens, are characterized by the prevalence of peat (also known as turf): organic matter in various stages of decomposition under various conditions, from tropical to arctic, from lowlands to mountainous highlands, from waterlogged to (comparatively) dry, from hardy grasslands to boreal swamps. Peat formation is typically the first step in the natural creation of coal.
Swamp-like, wet habitats consisting mainly of grasses, moss, and peat are called peatlands or bogs. They are important ecosystems. For peatlands to function, a constantly high water level is required. Raised bogs (peat bogs or upland moor) are formed above the groundwater level and are fed exclusively by rainwater. Since this contains few nutrients, few animals and plants live in these areas. Fens and mires (low moors) on the other hand are suffused by groundwater and are very rich in species and nutrients.
Over the course of millennia, peatlands have become a gigantic carbon store. Every year, peatlands worldwide remove 150-250 million metric tons of carbon dioxide from the atmosphere. Characteristically and in contrast to forests, the CO2 absorbed by the plants growing on peatland remains fixed in the peat after they die. Although they cover only 3% of the earth's terrestrial surface, they bind one third of terrestrial carbon in their peat layers. That’s about twice the biomass stored by forests, even if forests cover ten times as much of the global landmass.
The problem with peatlands, however, is that they are an endangered species: they are drained, used for agriculture and, particularly fatal, fertilized with nitrogen. Nitrogen-enriched peat begins a decomposition process similar to composting and the carbon contained is released again as CO2 and, even worse, as methane.
Many peatlands in cultivated and industrialized areas have lost their property as carbon sinks; instead, they have or at risk of becoming strong emitters of carbon compounds. We have to accept: Carbon sequestration in peatlands is a reversible process. It is very important to stop this process, and some governments are already enacting protection programs.
Remoorestation: Creating new carbon-rich ecosystems from hydrochar
Sequestering carbon as hydrochar (or biochar) offers an effective alternative to peat. Peat is much easier biologically activated than char and forms only metastable carbon sinks. Hydrochar and biochar are much less susceptible to biological degradation and are suitable to store carbon for long periods of time.
Protecting the current peatlands should have the highest priority in any global carbon strategy, in particular because they also represent a key tipping point in climate change. But the alternatives with more converted organic material as hydrochar and biochar, with their greater robustness against biodegradation, should get the attention they deserve.
Peatlands can only develop (or be created) where sufficient water is available. Conditions promoting peatland growth are found mainly in North America, Northern Europe, South America, North and South-East Asia and the Amazon basin. Parts of Russia, Alaska and Canada are particularly rich in peatlands. Peatlands of all kinds cover a total area of four million square kilometers, or about 3% of the Earth's land surface.
An emerging problem is that global precipitation is shifting geographically, so areas that previously had enough water to form peatlands are now drying out and peatlands are degrading. Other areas receive more water now but don’t have enough biomass build-up to form peatland. This is where biomass has to be accumulated to compensate for the peatlands disappearing elsewhere, and this is where hydrochar production has the most potential to make an immediate difference.
Further readings
Faizal Parish et al “Assessment on Peatlands, Biodiversity and Climate change: Main Report” UNEP, Global Environment Centre & Wetlands International (2008).
Fred Pearce “Why ‘Carbon-Cycle Feedbacks’ Could Drive Temperatures Even Higher” Yale Environment 360 (2020).
Michael Röhrdanz & Rainer Buchwald “Biokohle aus Moorgrünland-Aufwüchsen – Eignung grasartiger Landschaftspflege-Aufwüchse zur hydrothermalen Carbonisierung” (“Biochar from plant biomass of mire grasslands – Suitability of grasslike growth from landscape management for hydrothermal carbonization”), Naturschutz & Landschaftsplanung (2017).
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