.jpg)
The analysis performed herein represents a much-needed update and harmonization of the EROI literature, and it advances the conversation surrounding the viability of renewable resources in the energy transition process. A common argument is that the EROIs from renewable energy technologies are supposedly lower than those provided by fossil fuels, and that transitioning to RE technologies would therefore result in a large loss in net energy. The results of this analysis rebuke that sentiment, noting that the three most important technologies for the energy transition—wind, PV, and hydropower—all have EROIs at or above 10 (even when the output is weighted in terms of primary energy equivalent assuming a future-proof life-cycle grid efficiency of ηG = 0.7, i.e., 1 unit of electricity per 1.4 units of primary energy). This means that more than 90% of the energy produced by these technologies is delivered to society as net energy.
Perhaps more interesting still, the EROIs from liquid fuels, including the EROI from conventional oil production, are less than 10 once the costs of refining and delivery to the point-of-use are included. Oil is widely considered the most important fuel for the economy, used mostly in the transportation sector. This means that oil delivers less net energy to society for each unit invested in extraction, refining, and delivery than PV or wind. The transition to electric vehicles, according to these results, will actually increase the amount of net energy delivered to society (even more so when considering the higher efficiency of electrical power trains vs. internal combustion engines).
It is clear from these results that EROI estimates at the point of extraction can be wildly misleading. As a case in point, even if crude oil were measured to have an EROI of 1000 or more at the point of extraction, the corresponding EROI at the point of use, using global average data for the energy “cost” of the process chain, would still only be a maximum of 8.7. Furthermore, as the quality of oil, gas and coal continue to decline in the future, the energy “cost” of the associated process chains will increase, further reducing the EROIs. On the other hand, as the technologies used to harness renewable energy improve, the corresponding EROIs will continue to increase in the future.
Very good news. But thinking holistically, if two limits (say energy and greenhouse) are overcome, others will be encountered (landfill space, extinctions, food, etc) as exponential growth continues. Therefore, to make the energy transition "work", ending population and economic growth are essential. To make the energy transition work fast enough to avoid climate catastrophe, ending growth is almost certainly essential. To end growth we need social justice and better information systems. Better institutions to manage growth--starting with the obvious need for family planning campaigns to end population growth and liberate women. Current growth approximately triples power demand per century. Too many solar panels.
ReplyDeleteIt seems the embedded energy of all sources is a moving target, misrepresented by advocates and detractors of each option. Here is the scoop on solar PV: https://hiddenhistorycenter.org/wp-content/uploads/2020/01/BurningCoalTreesToMakeSolarPanels.pdf.
ReplyDeleteAnd here is the picture on mining copper, rare earths and silica: https://threadreaderapp.com/thread/1614178348694904837.html
Conclusions from 2019 Burning Trees paper at hiddenhistory:
Delete"Every step in the production of solar photovoltaic (PV)
power systems requires a perpetual input of fossil fuels -
as carbon reductants for smelting metals from ore, for
process heat and power, international transport, and
deployment. Silicon smelters, polysilicon refineries, and
crystal growers around the world all depend on
uninterrupted, 24/7 power that comes mostly from coal
and uranium. The only "renewable" materials consumed
in PV production are obtained by deforestation - for
wood chips, and by burning vast areas of tropical
rainforest for charcoal used as a source of carbon for
silicon smelters. So far, both media and journal claims
that solar PV can somehow "replace fossil fuels" have not
addressed the non-renewable reality of global supply
chains necessary for mining, manufacturing, and
distribution of PV power systems. Based on current
world production levels of solar PV, an attempt to
replace conventional electricity production with solar
PV would require a dramatic increase in the amount of
coal and petcoke needed for silicon smelting, along with
the increased cutting of vast areas of forest for charcoal
and wood chips/"