New research published in the journal Nature Energy has warned that society may be heading towards a ‘net energy cliff’ unless it undertakes a rapid shift to renewables, as fossil fuels become increasingly harder to access.
As reserves are depleted, fossil fuel supplies will require exploration in harder to reach places, forcing it further offshore, and digging deeper to reach the remaining supplies, and at greater cost.
The study was completed by researchers at the Sustainability Research Institute at the University of Leeds and has found that manufacturing processes for solar panel and wind turbines have continued to improve, while access to fossil fuel resources continues to get more difficult.
The study examined the energy-return-on-investment (EROI) for various energy sources, which is a way of comparing of the amount of energy that is used in the process of extracting a particular energy source, to the amount of useable energy that is gained through extraction.
As easy to access coal, gas and oil resources are depleted, harder to access resources will require more work, and consume more energy, to extract. Researchers fear that when efficiency losses are taken into account, such as energy lost during electricity generation, society may face ‘falling off a cliff’ with regards to the amount of useful ‘final energy’.
“We find it credible that declining EROI ratios of fossil fuels will lead to constraints on the energy available to society in the not-so-distant future, and that these constraints might unfold in rapid and unexpected ways,” the paper said.
The researchers say it could lead to a snowball effect, that more and more fossil fuels are consumed in the search for harder to reach reserves, sending energy availability “off a cliff” and having a disastrous contribution to global warming.
“This translates to an urgent need to include fossil fuel EROI at the final energy stage in energy–economy models, to study possible socioeconomic impacts and responses. These insights are urgently required, as future policy and energy infrastructure investment decisions are being made now to meet climate change mitigation commitments.”
For example, it is possible to compare the amount of energy used in the manufacture of wind turbines, such as the production of steel towers and fibreglass for the blades, to the amount of electricity generated by the wind turbine during its operating life.
It is an often encountered misconception that renewable energy technologies require more energy in their manufacture than they produced during their operating lifetime.
The new research has shown that not only is this a misconception, but that renewable energy technologies may soon provide a better energy-return-on-investment than fossil fuel resources.
Studies show that solar PV panels generally produce between 10 and 20 times as much energy as is used in their manufacture.
Wind turbines have similar energy-return-on-investment, generally producing between 15 and 30 times the energy used to manufacture and install the turbines.
Generally, the energy-return-on-investment for renewable energy technologies have been improving, as efficiencies improve and production processes become more refined.
The energy-return-on-investment is presumed to be high for fossil fuel resources, with coal, oil and gas all generally providing a 25:1 energy return ratio, with some projects achieving returns of up to 80-times.
However, these metrics have historically been determined based on ‘primary’ energy production and do not account for the amount of useful ‘final’ energy once losses and efficiencies are accounted for.
The researchers find that it there’s an important distinction to be made between ‘primary’ energy production (energy produced at the point of extraction) and the amount of ‘final’ energy produced (the amount of energy made available to customers, such as in the form of electricity). A significant portion of energy can be lost through efficiency losses when ‘primary’ is converted to a form of ‘final’ energy.
“Conceptually, the estimation of fossil fuel EROI at the final energy stage is much more relevant to society and the economy than at the primary energy stage, because final energy is much closer to end energy services. It also enables a fairer comparison between fossil fuels and renewables,” the researchers said.
The research completed by the Leeds University research team found that when the overall life-cycle energy use is examined, factoring in energy losses when coal and gas are used for electricity generation, that the energy returns are similar to sources of renewable electricity.
As fossil fuels become harder to access, the energy return ratios will continue to fall, leading researchers to suggest that a rapid transition to renewable energy should occur while fossil fuels are still abundant.
Lobby groups, such as the Mineral’s Council of Australia, love to point out that many components of renewable energy technologies are produced using the products of fossil fuels.
Perhaps they can concentrate using the fossil fuels we have now to build more renewables and prepare society for a post-carbon future.