LCA Nuances

Lifecycle analysis numbers are only as reliable as their input assumptions. Two variables move them dramatically: methane leakage rate for natural gas, and manufacturing grid intensity for solar.

Methane leakage. Gas burns cleaner than coal at the point of combustion, but methane leaking from wells and pipelines before reaching a burner has 80x the warming potential of CO2 over 20 years. At 1% leakage, gas's lifecycle advantage over coal holds comfortably. At 3.5%, gas is roughly even with coal on climate impact. The EPA estimates US leakage at ~1.4%, but field measurements in major basins have clocked 2-5x higher in specific regions. Which number enters your LCA determines whether gas looks like a bridge fuel or a dead end.

Manufacturing location. A solar panel made using Chinese coal electricity carries roughly 40-80 gCO2/kWh over its life. The same panel made with cleaner grid electricity: 20-30 gCO2/kWh. Both are far below coal (800+), but the 3x spread matters when comparing gas peakers (400-500 gCO2/kWh) versus solar in a close policy call.

A senator's staff memo argues that replacing coal with domestic gas cuts lifecycle emissions by 50%, assuming 1.2% methane leakage.

What happens to that claim if the actual leakage rate in that basin is 3%?

The 50% cut shrinks to roughly 25-35%. At 3% leakage, gas lifecycle emissions rise to 600-700 gCO2/kWh. The policy conclusion may still hold, but the magnitude is halved. If a carbon price or renewable alternative is in play, the decision could flip.

A useful policy reader asks: What leakage rate does this gas LCA assume? What grid powered the solar manufacturing? How sensitive is the conclusion to those inputs?

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