Wood Vault: remove atmospheric CO2 with trees, store wood for carbon sequestration for now and as biomass, bioenergy and carbon reserve for the future

Table 5 Unexploited wood sources in the US (Perlack et al. [6]; dry ton converted to wet tonne or tCO₂ using a conversion factor of two)

Source		Availability per area tCO₂ ha⁻¹	State MD (25,000 km²) MtCO₂ y⁻¹	US (unexploited/total) MtCO₂ y⁻¹	Permanence and durability after WHS storage	Current use
Urban wood residue (56 out of 124Mt total)	Woody yard trimmings (natural wood) MSW	0.2	0.5	4/20 (4 out of total of 20)	1000+ years	Partially used for mulch, energy
	Construction residue			17/23	100+ years
	Demolition debris			23/55	100+ years
	Wood MSW (Furnitures +)			12/26	100+ years
Forest thinning (128 Mt)	Thinning for fire prevention (fuel treatment)	0.4	1	120	1000+ years (large pieces) 100 years (smaller pieces)	Not common (needs policy and investment)
Logging residue		0.3	0.75	93	100+ years	Partially used for mulch, energy
Other removals (land clearing precommercial treatment)		0.12	0.3	35
Forest products industry wastes (Mill residues)		0.05	0.125	16/321
Total		1.1	2.8	328

Available = Generated-(Recovered + Combusted + unusable). Unusable sources such as contaminated wood were already excluded. Potential availability per unit area is assumed to be distributed over US forested land of 3 Mkm²

ISSN: 1750-0680