Energy Transitions: Changing Physical Forms

By Siddharth Singh, 18th August, 2015

An initiative on the geography of transport systems by Hofstra University (New York) hosts an interesting graph on energy transitions from the 1800s. Unlike most others which represent the changing consumption of various fuels, this one illustrates fuel use transitions by the physical form that energy takes: solids, liquids and gases.

The graph captures the fuels (primary*) used to generate energy (both primary and secondary*). Solar, wind and other renewables are not captured in this graph.

Energy transitions are triggered by various factors, including: intensity of energy content, ease of availability, ease of transport, reliability, storability, flexibility, safety, cleanliness and affordability.

The graph projects that gaseous forms of energy will dominate in the future. The gases under consideration are, initially, natural gas (which is already being increasingly used for various activities, particularly power generation), and later, hydrogen (which is largely in the R&D phase at the moment).

*Post Script: Energy is classified into primary and secondary forms depending on how they are extracted and prepared for consumption. Definitions of these classifications have been made by several institutions; I prefer the ones by Sara Øvergaard, prepared for the International Recommendation on Energy Statistics in 2008. These definitions are:

“Primary energy is energy embodied in sources which involve human induced extraction or capture, that may include separation from contiguous matrial, cleaning or grading, to make the energy available for trade, use or transformation.”

“Secondary energy is energy embodied in commodities that comes from human induced energy transformation.”

An illustrative representation of this would be:

The author is available on Twitter @siddharth3.