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The Understand Energy Learning Hub is a cross-campus effort of the Precourt Institute for Energy.

Current Energy Landscape

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Note: This figure does not include difficult-to-measure traditional biomass (~7%).

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Percentages do not add to 100 due to rounding of individual categories.

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*Other includes electricity generated from resources not specified elsewhere (e.g., pumped hydro, non-renewable waste and heat from chemical sources)

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Percentages do not add to 100 due to rounding of individual categories.

Sources: Energy Institute. Statistical Review of World Energy. (2023); ElA. Total Energy. Energy Overview Table 1.3, Electricity Table 7.2a. (2022)

Energy Systems

An energy system converts primary energy resources (like fossil fuels or wind) into energy currencies (like electricity) to provide services humans want and need. 

Diagram of an energy system showing how energy resources relate to energy currencies, energy storage, and energy services

World Energy System Overview

The world energy system is only 42% efficient. 58% is lost (rejected energy).

Diagram showing the the flow of energy from sources to consumption
Source: LLNL 2014. Data is based on IEA's Extended World Energy Balances (2013 Edition)
All quantities are rounded to 2 significant digits and annual flows of less than 0.05 PJ are not included. Totals may not equal sum of flows due to statistical differences. Imports and Exports represent gross global trade. Further detail on how all flows are calculated can be found at http://flowcharts.llnl.gov

View larger | Download tabular data World Energy Flow 2011 (XLSX, 11KB)

US Energy System Overview

The US Energy System is only 33% efficient. Two-thirds is lost (rejected energy).

Diagram showing the flow of energy from sources to consumption in the US in 2021
Source: LLNL March, 2022; DOE/EIA MER (2021).
Distributed electricity represents only retail electricity sales and does not include self-generation. EIA reports consumption of renewable resources (i.e., hydro, wind, geothermal and solar) for electricity in BTU-equivalent values by assuming a typical fossil fuel plant heat rate. The efficiency of electricity production is calculated as the total retail electricity delivered divided by the primary energy input into electricity generation. End use efficiency is estimated as 65% for the residential sector, 65% for the commercial sector, 21% for the transportation sector and 49% for the industrial sector, which was updated in 2017 to reflect DOE's analysis of manufacturing. Totals may not equal sum of components due to independent rounding.

View larger | Download tabular data Estimated US Energy Consumption 2021 (XLSX, 11KB)