煤炭储量丰富，分布广泛。 与煤炭价格相比，天然气价格波动巨大，而且，在矿物燃料殆尽的情况下，其长期趋势也不明朗。
Unlike prices for coal, which is abundant and dispersed geographically, gas prices are subject to significant volatility, and the long-term trend in the face of fossil fuel depletion is uncertain.