Scope 1–3 CO₂e会計とライフサイクル評価（LCA）のシステム境界整合：化石燃料火力・原子力発電所の比較ケーススタディ

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🔬研究者:LCAとScope会計の境界整合手法と、電源別のScope配分・感度要因（メタン漏洩、資本財）の定量例を提供する。

🏢実務担当者:自社のScope 3算定や電源調達・販売に伴うScope配分の設計、CCSや原子力調達時の開示根拠として活用できる。

🏛政策担当者:電源別排出比較やScope 3開示制度の設計において、組織境界とLCA境界の違いを踏まえたガイダンス整備の参考になる。

The objectives of this research are twofold: First, we quantify cradle-to-grid (CtG) life-cycle greenhouse-gas (GHG) intensities for three major electricity-generation technologies and map these results to the GHG Protocol Scopes 1–3. We do so by harmonizing system boundaries across technologies and disaggregating impacts into direct operational emissions (Scope 1), purchased-energy emissions (Scope 2), and upstream/downstream value-chain emissions (Scope 3). Second, we examine how organizational GHG accounting aligns with, and can diverge from, LCA boundary definitions by comparing nuclear (PWR and BWR) generation with coal-fired and natural-gas combined-cycle (NGCC) power plants, and by explicitly linking scope classifications to CtG and cradle-to-grave (CtGr) LCA boundaries (with CtG defined at the busbar/plant gate). Results show that nuclear electricity has a very low life-cycle GHG intensity relative to dispatchable fossil alternatives. Unlike fossil generation, nuclear emissions occur predominantly in Scope 3, especially in the front end of the uranium fuel cycle (mining, conversion, enrichment, and fuel fabrication) and in embodied emissions from capital goods, rather than in Scope 1 emissions from plant operations. By contrast, coal and NGCC remain materially higher due to dominant Scope 1 combustion emissions alongside nontrivial Scope 3 fuel-cycle contributions. For NGCC, upstream methane leakage is a pivotal Scope 3 driver that can materially shift CtG outcomes compared with Scope 1 combustion-only reporting. With carbon capture and storage (CCS), residual fossil GHG intensity is governed by capture rate, efficiency (energy) penalties, and upstream fuel-cycle emissions. We also find that scope allocations can change when moving from a plant-owner (investor-owned) boundary to a utility holding-company boundary, particularly where generation is not operationally controlled and purchased electricity for resale becomes a major indirect category. Overall, the study provides a transparent mapping between LCA boundaries and Scopes 1–3 that reduces boundary mismatches in technology comparisons and sensitivity analyses (e.g., methane leakage and capital-goods emission burdens) and supports clearer, more credible emissions reporting for regulators, investors, and other stakeholders.

• semanticscholar https://doi.org/10.63002/gres.405.1801first seen 2026-10-22 05:22:32 · last seen 2026-11-06 05:16:35