Atmosmare organisoi asiaan liittyvän demonstraation Lietoon
Only a very limited amount of carbon can be stored per hectare in a growing forest. The largest per-hectare timber volumes measured in our natural forests have been between 700 and 800 cubic meters of stemwood, which translates to approximately 150 or a maximum of 200 tons of carbon, depending on the tree species. The organic matter in tree roots and topsoil can also contain 100 – 200 tons of carbon per hectare.
On good soil, the carbon stock of the above-ground part of the tree stand can be increased somewhat beyond the maximum values found in natural forests by thinning the tree stand appropriately. In Finland and its neighboring areas, there are some old forests or stands that have been relatively thinned or originally grown sparsely, from experimental plots established in which per-hectare stemwood volumes of up to 1,200 – 2,000 cubic meters have been measured. In such areas, there have been only 150 – 450 trees per hectare grown larger than normal.
These figures are already very difficult to exceed, even under ideal growing conditions. At some point, a limit is reached, after which the forest’s carbon stock no longer grows but gradually begins to decrease as trees fall or rot standing.
However, there are a number of ways by which it would be possible to store significantly larger amounts of wood and its contained carbon per hectare. Discussions have brought up examples such as submerging tree trunks to the bottom of lakes or compacting them into bogs.
An even simpler and cheaper method would be to collect logging residues, wood generated from sapling and first thinnings, and potentially also reed plants cultivated in fields and sphagnum moss growth from bogs (every few years) into thick piles and cover them with an inexpensive but at least 50–100 year durable waterproof cover.
If piles composed of small-sized wood and possibly other biomass were compacted or rolled into relatively dense piles, it would be possible to store an estimated 80,000 cubic meters of wood or an amount of biomass equivalent to 20,000 tons of carbon per hectare in ten-meter high storages, roughly a hundred times more than in a growing forest.
If the piles are protected from rain and established on rocks or on rocky or gravelly soil, the biomass can easily be kept dry enough to prevent it from rotting and its contained carbon from being released into the atmosphere as carbon dioxide. In practice, wood does not rot if its moisture content remains below 20 percent.
Old, disused barns could be used for this type of climate change-mitigating storage of organic matter, which is essentially carbon – approximately 50 percent of all organic matter is carbon. Many other types of disused buildings, such as old factories or uninhabited houses in remote areas, should perhaps be harnessed for similar use. Even more essential would be to develop the cheapest possible ways to protect large wood and biomass piles from rainwater for at least a hundred years without the waterproof cover needing constant renewal. Such carbon storages could indeed be established in an emergency, as much as needed.
Biomass (carbon) storage areas could also be used, if desired, for solar power generation and rainwater collection. The waterproof cover of biomass piles can consist of solar panels and could be designed so that water falling on the pile cover can be collected in areas where there is a water shortage during some seasons.
Atmosmare is planning to organize a demonstration that tests and illustrates the possibilities of this approach on its forest plot located in Lieto. The demonstration consists of filling an old barn with wood and, at a later stage, also storing wood and other biomass under a simpler waterproof cover.
If, for example, one-seventh of Finland’s current greenhouse gas emissions (approximately 60 million tons of carbon dioxide equivalent per year) were eliminated through this kind of “barn-carbon storage,” approximately one square kilometer, or one hundred hectares, of wood and other biomass storage areas would need to be established annually for this purpose.
