Sociology

Investment (military)

Population

Biology

Politics

Per capita

Energy budget

Macroeconomics

Animal science

Demography

Engineering

Environmental economics

Return on investment

Political science

Economics

Natural resource economics

Renewable energy

Ecology

Efficient energy use

Production (economics)

Net energy

Environmental science

Waste management

Fossil fuel

Nature Energy

Low-carbon energy transitions aim to stay within a carbon budget that limits potential climate change to 2 °C—or well below—through a substantial growth in renewable energy sources alongside improved energy efficiency and carbon capture and storage. Current scenarios tend to overlook their low net energy returns compared to the existing fossil fuel infrastructure. Correcting from gross to net energy, we show that a low-carbon transition would probably lead to a 24–31% decline in net energy per capita by 2050, which implies a strong reversal of the recent rising trends of 0.5% per annum. Unless vast end-use efficiency savings can be achieved in the coming decades, current lifestyles might be impaired. To maintain the present net energy returns, solar and wind renewable power sources should grow two to three times faster than in other proposals. We suggest a new indicator, ‘energy return on carbon’, to assist in maximizing the net energy from the remaining carbon budget. Energy systems are transitioning from fossil fuel sources to renewable sources with lower net energy generation. Using the concept of energy return on investment, this study finds that net energy per capita is likely to greatly decrease without more efficiency savings or energy infrastructure.

Implications of net energy-return-on-investment for a low-carbon energy transition