Revised 28 February 2025


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Energy is required to explore and identify where the most concentrated reserves of fossil fuels are located. The mining of materials for plant and machinery also requires the use of energy. More energy is then required to construct the necessary plant and machines to extract the fossil fuels from the ground and to run the plant and machines. The reserves of fossil fuels in the ground which are extracted represent gross energy. Net energy, also known as a surplus, is what is left over for use after subtracting the energy used in exploration and extraction (Hall 2016). The annual rate of production of all forms of fossil fuels eventually peak, followed by a progressive reduction in the rate of production due to increasing energy costs of extraction (Bentley 2016).


In Figure 1 below, Delannoy and colleagues (2021) chart the history of oil liquids production from 1950 to 2021. Oil liquids includes natural gas liquids, biofuels, and shale. The Energy of production is plotted along the Y-axis and the date in years are plotted along the X-axis. Delannoy and colleagues then project oil liquids production based on the Globalshift model (Smith 2015) which ignores carbon budgets required to mitigate the impact of fossil fuels. In other words, a continuation of current business as usual. 


The cross-hatched light-yellow area at the top of the plotted areas represents the energy required to produce net energy. All stacked areas below this light-yellow area represents net energy available at the point of extraction. The dark grey area at the bottom of the chart represents field oil. 



Figure 1: Energy Production of Oil & Gas From 1950 Projected to 2050 (Delannoy et al. 2021) 


When field oil was drilled in 1950, it required about one unit of investment in energy to provide a return of 50 units of energy, an EROI ratio of 50:1. Net field oil peaked about 1979. The combination of net field oil and off shore drilling to 500 metres coloured light grey peaked about 2004. Off shore drilling to 2,000 metres, shale tight oil, oil sands, onshore natural gas, and biofuel have allowed total net energy to increase until about 2020. 


According to Delannoy and colleagues (2021), total net oil liquids will peak about 2024 and then continuously decline until 2050. Other sources of energy include coal, nuclear energy, and renewables. Coal can be converted into a liquid form of fossil fuels, but any conversion involves losses in energy. Time has run out for expanding the use of nuclear energy. New nuclear power stations would be up and running after the next two most critical decades of transition and mitigation of climate change. (Murphy 2021). 


Over the next number of decades, global net energy production of key convenient forms of fossil fuels will decline. We need to transition as soon as possible from these fossil fuels to sustainable energy sources before the annual rate of net energy production declines to a level where a transition would be physically impossible.