Scenario-Based Economic Screening of Forest-Residue Gasification Utilization Pathways in Korea: Break-Even Conditions and Uncertainty

The economics of alternative product-gas uses from forest-residue gasification remain poorly bounded. This study screens four pathways in South Korea: hydrogen with fuel-cell power (S1), gas-engine power (S2), compressed direct gas supply (S3), and hydrogen-limited methanation with upgrading (S4). A common product-gas flow of 25,000 Nm3 day−1, 328.5 operating days per year, a 20-year period, and a 4.5% real discount rate were applied to a documented air-blown downdraft gas (base case; lower heating value 4.74 MJ Nm−3) and, as an upper bound, to a nitrogen-lean gas (9.26 MJ Nm−3). Under a downstream-only boundary (A), all four pathways have negative base-case net present values (NPVs; KRW billion): −58.83 (S1), −5.72 (S2), −3.61 (S3, with purchased compression electricity), and −33.83 (S4). Adding a common upstream allowance of KRW 11.80 billion (boundary B) deepens all of them. Boundary B break-even prices are KRW 1796 kWh−1 (S1), 597 kWh−1 (S2), 40.2 MJ−1 (S3), and 157 MJ−1 (S4). Only with the nitrogen-lean upper-bound gas does S2 reach a positive boundary A NPV (KRW 3.35 billion). Monte Carlo simulation (10,000 iterations, bounded physical inputs) gives no positive NPV for any pathway under either boundary in the base case, and, only with the nitrogen-lean gas, simulated frequencies of positive boundary A NPV of 80.5% (S2) and 39.0% (S3). Residue-cost variation over a 30–100 km radius shifts NPV by less than KRW 1.2 billion. The results are conditional screening thresholds, not evidence of commercial feasibility.