According to the International Energy Agency in their most recent World Outlookthe amount of money required to meet energy needs over the next twenty five years is $51tn. That is in real terms measured in 2013 dollars and amounts to approximately 14 times current German gross domestic product.

Energy investment as defined by the IEA includes the exploration, production, distribution, transportation and processing of all forms of energy. It includes new ventures and replacement of the existing capital stock. Some $30tn of the total is expected to be devoted to fossil fuel extraction, transportation and oil refining, while most of the remainder goes to the power sector including $7.4tn to renewables and $1.5tn to nuclear; $8.7tn goes to the development of transmission and distribution systems. This is, of course, an indicative forecast built around the IEA’s assumptions of some progress towards emissions reduction. The detail is less important than the total.

Energy investment is driven by effective demand — the combination of population numbers (up by 1.5bn to 2bn worldwide over the period ) and by the spread of prosperity. Something like 1bn additional consumers have joined the commercial energy market since the turn of the century. That level of expansion is expected to continue but the forecast is far from utopian. Many hundreds of millions living mainly in sub-Saharan Africa and south Asia will still be outside the market and in subsistence lives in 25 years time.