UN Report Trumpets the Benefits of Nuclear as a Electricity Generation Source

The UN Economic Commission for Europe (UNECE) recently released a report entitled “Life Cycle Assessment of Electricity Generation Options” (UNECE Report; Report).  The Report analyzes the environmental profiles of the full lifecycle of various technologies in order to evaluate their “all in” environmental costs—such as greenhouse gas emissions (GHG), human toxicity, water use, and other environmental and health metrics of different electricity sources—including wind, solar, coal, gas, hydro, and nuclear. In a finding that may be very surprising to many, but likely not those in the nuclear field, nuclear had some of the smallest impacts on the environment out of all the electricity sources analyzed.


The UNECE Report emphasized that decarbonization needs to be pursued with a “well-informed energy policy design.”  Report at 6.  To accomplish this, stakeholders need to ensure that the “cradle-to-grave” environmental impacts of electricity generation are evaluated, including mining the materials used in the facilities, manufacturing their components, and constructing, operating, and decommissioning them. Report at 8. Notably, the Report wants to ensure that we do not “shift the problem” by reducing environmental impacts from operating power generation sources, only to shift them someplace else, like to the operations needed to produce the materials for facilities, or to the land requirements needed to support them. Report at 8.

The Report undertook this evaluation for a wide range of electricity generation sources to better inform stakeholders in the decision-making process.  It notes upfront—and in bold—that all electricity generation sources create environmental impacts over their life cycles, and these impacts vary widely across sites and designs. Report at 7. However, as set forth in the Report, of all the electricity sources evaluated, nuclear was found to have some of the smallest impacts to the environment.  Across its entire life-cycle, nuclear power emits less greenhouse gases and uses less land than the other power sources studied, including all variants of wind and solar. Nuclear is also ranked as one of the most environmentally-friendly generation sources—second to only one variant of hydropower—when measured against the other power sources for consumption of mined minerals and metals, carcinogenic effects, and freshwater eutrophication.

As this blog and its authors routinely note, including in our recent blog summarizing the latest UN Intergovernmental Panel on Climate Change (IPCC) report, we must use everything in our arsenal to reduce GHG emissions.  Moreover, we need immense sources of energy that produce minimal greenhouse gases and can support a reliable electricity grid.  This will require the deployment of a range of technologies—including wind, solar, hydrogen, nuclear, battery storage, and carbon-capture and sequestration.  There is no one technology that is a “silver bullet” to combatting climate change.  Difficult decisions must therefore be made by stakeholders, who need objective and thorough supporting research to make informed choices.  As the UNECE makes very clear, all electricity sources impact the environment, and not necessarily in the way stakeholders might realize.

The Report further references the recent IPCC report, stating that because the most ambitious climate mitigation scenarios require electrification of ever-greater swathes of the U.S. and world economy, it is vital to evaluate the environmental impacts of various energy sources for future electricity generation. Report at 6. The UNECE Report did exactly that.  It studied six variations of hard coal technology, two variations of natural gas, two of hydropower, eight of solar power including photovoltaic, three of wind power, and conventional nuclear power.  The Report also assessed twelve regions worldwide, with varying load factors, methane leakage rates, background grid electricity consumption, and other factors.  Its objective was to assess the environmental impacts of delivering one kWh of electricity to the grid, on a global average, for 2020.

Conventional nuclear energy for electricity generation fared supremely well, and nuclear outpaced all or almost all studied generation sources in the following areas:

  • Carbon emissions. The Report’s model found that out of the 22 technologies studied, nuclear had the absolute lowest lifecycle greenhouse gas emissions, with an average of just 5.1-6.4 g CO2 eq./kWh (a measure of the GHG emission intensity of electricity generation, with a range to account for technological and regional variations). And it wasn’t even that close.

For comparison, the second-lowest emission intensity is 6.1-11 g CO2 eq./kWh for 360 MW hydropower (a figure that is much higher for 660 MW hydro, at 85-147). Solar photovoltaic ranges anywhere from around 8 to 83 g CO2 eq./kWh, depending on the specific technology and other factors.  Natural gas and coal are of course much higher, with hard coal ranging dramatically from a low of around 150 to a high of roughly 1,100 g CO2 eq./kWh.  Natural gas ranges from 403 to 513 by this metric—also not even in the same ballpark as nuclear.

  • Land occupation. The Report also shows that nuclear technology on average has the lowest lifecycle land occupation requirements out of any technology studied, dramatically lower than all types of coal, natural gas, and renewables.
  • Carcinogenic effects. Contrary to its unfairly-maligned reputation as a source of carcinogens—largely owing to the effects of nuclear radiation from atomic bombs and anachronistic, irresponsible nuclear weapons testing procedures—the production of nuclear power for electricity generation has the second-lowest rate of carcinogenic effects out of the 22 technologies studied. This is behind only 360 MW hydro, but ahead of 660 MW hydro and all other solar and wind variations studied.
  • Freshwater eutrophication. Freshwater eutrophication is caused by emissions of phosphorus compounds into freshwater bodies such as rivers and groundwater. For this metric, nuclear generation is the second best of the 22 technologies studied, again behind only 360 MW hydro, and ahead of all eight solar variations studied and all three wind variations.
  • Consumption of minerals and metals. Once again, nuclear outperformed all other electricity generation sources—both fossil fuels and renewables—except for 360 MW hydro, in its consumption of minerals and metals. The high energy density of the uranium (and sometimes plutonium) used in conventional nuclear reactors leads to a relatively minimal mining area per kWh.

The main downsides to nuclear generation as expressed in the Report are its water use requirements and its ionizing radiation.  However, the Report contextualizes these drawbacks against nuclear’s low carbon emissions and the other striking environmental benefits mentioned above.  And even with respect to radiation, the Report found that coal and geothermal cause more radiation dose to the public than does nuclear—and radiation from all types of studied power generation is far less than the average dose received by airline pilots.

To note, the Report focuses on conventional nuclear generation—as opposed to advanced reactor technologies and fusion—yet conventional nuclear still outshines competing renewable and fossil fuel generation sources on many key environmental indicators.  The gap between nuclear and the rest of the field further widens when one accounts for advanced reactor technologies, not to mention the emerging prospect of commercialized fusion energy.  These technologies have the potential to produce even more impactful environmental advantages for nuclear generation, on top of the significant benefits conventional nuclear power already boasts.

Many variables and detailed analyses went into the UNECE Report, and we recommend it as necessary reading for policy makers and other stakeholders—as well as supporters, opponents, and those still on the fence about nuclear power.  We also recommend it for anyone interested in becoming or staying informed about decarbonization of the electricity sector.  Combatting climate change is a complex task, with multiple facets that need to be understood and woven together into a coherent and effective strategy.  And this requires policy makers coming to the table with a full appreciation of what needs to be achieved.  The Report employs an in-depth quantitative methodology without a corresponding agenda, and is a significant contribution to the energy transition discussion and implementation.


Authored by Amy Roma and Rob Matsick.


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