Carbon payback period and carbon offset parity point of wood pellet production in the South‐easternUnited States

Abstract

This study examines the effect of methodological choices to determine the carbon payback time and the offset parity point for wood pellet production from softwood plantations in the South-eastern United States. Using the carbon accounting model GORCAM we model low-, medium-and high-intensity plantation management scenarios for a single stand level, an increasing stand level and a landscape level. Other variables are the fossil-fuel reference system and the electrical conversion efficiency. Due to the large amount of possible methodological choices and reference systems, there is a wide range of payback times ( 1 year at landscape to 27 years at stand level) and offset parity points (2-106 years). Important aspects impacting on the carbon balances are yield, carbon replacement factor, system boundaries and the choice of reference scenario used to determine the parity point. We consider the landscape-level carbon debt approach more appropriate for the situation in the Southeastern United States, where softwood plantation is already in existence, and under this precondition, we conclude that the issue of carbon payback is basically nonexistent. If comparison against a protection scenario is deemed realistic and policy relevant, and assuming that wood pellets directly replace coal in an average coal power plant, the carbon offset parity point is in the range 12-46 years; i.e. one or two rotations. Switching to intensively managed plantations yields most drastic reduction in the time to parity points ( 17 years in 9 of 12 cases).

Renewable Energy from Forest Residues—How Greenhouse Gas Emission Offsets Can Make Fossil Fuel Substitution More Attractive

“…We do not quantify the impact of the temporal delays in CO 2 emissions from decaying forest residues left on a forest site versus the CO 2 emissions that occur immediately if residues are instead supplied to a co-generation facility for fuel substitution. As a result, our cost assessment does not consider the temporal profiles of GHG emissions or periods of carbon debt repayment (such as presented in [39] and [25]), which can be quite short in the case of forest residues substituting for fossil fuels [20,21]. While a gradual decay of forest residues over several years does translate into delayed CO 2 emissions, our focus here is the development of indicative national cost curves.…”

“…For example, additional utility can be extracted from the capacity of forest biomass to offset GHG emissions when used to replace fossil fuel combustion for energy generation [20][21][22][23]. The combustion of residues can potentially achieve GHG emissions neutrality in a very short period [24,25]. A number of studies have demonstrated the use of various types of residual biomass for heat and electricity production [14,[26][27][28] and have found that residue biomass is only economically viable without government support when the avoided GHG emissions are given a market value.…”

Logistical, economic, environmental and regulatory conditions for future wood pellet transportation by sea to Europe: The case of Northwest Russian seaports

“…However, greenhouse gas (GHG) emissions are reduced for empty return trips in comparison to loaded trucks. Jonker et al have assumed (based on Hamelinck et al [24]) a 60% GHG emission reduction for a 100-km distance for 16-32 ton empty versus loaded trucks [58]. Another question is to what product chain the emissions from return trips by loaded trucks would be allocated.…”

“…One important quality aspect is that a part of the dry matter of wood pellets is lost during handling in export ports and shipment [58], which decreases the heating value. Jonker et al [58] have assumed total dry matter loss of wood pellets as 7% for the whole supply chain from forest to power plant. The extent of the loss, however, depends on the specific supply chain.…”

“…Both [21] and Cocchi et al [74] evaluate non-renewable GHG emissions from wood pellet logistics by ship (including necessary truck and railway transportations) as being significant. Jonker et al [58] have calculated the carbon balance in their analysis of the wood pellet supply chain from Southeastern USA to Europe. The GHG emissions are supply-chainspecific, depending on the production and transportation volume.…”