An equation for global energy efficiency gains in the long-run
研究发现全球能源效率（GDP与最终能源消费之比）在过去两百年间随累积能源消费呈指数增长，并据此估算从新石器时代到1820年效率翻倍，此后又增长约两倍。该方程可用于分析历史及校准未来能源消费情景。
This work focuses on the global economic efficiency of energy use, defined as the ratio at world scale of Gross Domestic Product to Final Energy Consumption, including food for humans and feed for draft animals. With a simple hypothesis of energy efficiency gains being proportional to economic activity, it evidences that for the last two centuries energy efficiency grew on average exponentially with the cumulative energy consumption. By extrapolating this relationship, I estimate that the global economic efficiency of energy doubled or so from the Neolithic transition up to 1820, whereas it roughly tripled since then. Concerning the present energy transition, the International Energy Agency's scenario for “Net zero emission” by 2050 would reverse a recent slowdown in efficiency gains and retrieve the trend of the last two centuries, eventually overpassing it. The equation thus provides a historical reference for analyzing the past and calibrating future energy consumption scenarios.