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| Fig. 1: Electricity generation by source in 2022. [3] 91% of electricity generation came from renewable energy sources (Source: J. Contreras) |
In 2014, the WWF recognized Uruguay as a green energy leader for its significant investments in renewable energy. [1] Investments in hydroelectricity, wind, and solar have allowed Uruguay to decarbonize its grid over the past decade and popularized it as an example of sustainable living. [2] As can be seen in Fig. 1, more than 90% of electricity generation in the country came from renewable sources in 2022. [3] However, electricity represents only one sector of the energy economy and fossil fuels have many uses including fuel for transportation and heating for industrial processes, homes, and businesses. To more accurately understand Uruguay's environmental impact, it is necessary to examine fossil fuel use across all sectors of the economy.
Electricity generation by source is not an accurate metric for understanding Uruguay's carbon footprint because it captures only the output of electricity produced and not the amount of energy consumed to generate it. Some energy is lost as heat in all energy conversion processes due to the second law of thermodynamics. When examining fossil fuel use, it is more accurate to refer to the inputs for electricity generation, which accounts for the energy loss associated with the conversion to electricity in power plants. This will provide a more complete picture of the country's use of fossil fuels.
To calculate the inputs for electricity generation from fossil fuels, I referred to Uruguay's energy balance report last published by the Ministry of Industry, Energy, and Mining in 2022. It showed that a total of 1564.8 kilotonne of oil equivalent (ktoe) was used for electricity generation and 223.1 ktoe, 33.7 ktoe, 0 ktoe, and 0 ktoe came from gas oil, fuel oil, gasoline, and natural gas respectively for a total of 256.8 ktoe from fossil fuels. [3]
Converting to joules per year we have
| 256.8 ktoe y-1 × 1000 toe ktoe-1 × 4.18 × 1010 J toe-1 | = | 1.073 × 1016 J per year |
To assess fossil fuel reliance across all economic sectors, I looked at figures from Uruguay's primary energy matrix, which showed a total 5,668.8 ktoe energy supply in 2022. Of those 5,668.8 ktoe, 71.9 ktoe, 2419.3 ktoe, and 1.7 ktoe came from natural gas, oil, and coal respectively. [3] Summing and multiplying we have
| 71.9 ktoe + 2419.3 ktoe + 1.7 ktoe | = | 2,492.9 ktoe |
| 2,492.9 ktoe y-1 × 1000 toe ktoe-1 × 4.18 × 1010 J toe-1 | = | 1.044 × 1017 J per year |
Comparing the two figures, we can see that inputs for electricity generation make up approximately
| 1.073 × 1016 J 1.044 × 1017 J |
= | 0.103 |
or 10.3% of the energy derived from fossil fuels, meaning the majority (89.7%) is used in other economic sectors.
Then, I calculated the total amount of electric energy consumed in Uruguay in 2022 to understand the share that came from the fossil fuel inputs. 4,846 ktoe were consumed in 2022 and 21% of that energy was electric energy. [3] Multiplying and converting we have
| 4,836 ktoe y-1 × 0.21 | = | 1015.56 ktoe y-1 |
| 1015.56 ktoe y-1 × 1000 toe ktoe-1 × 4.18 × 1010 J toe-1 | = | 4.245 × 1016 J per year |
The previously calculated inputs for electricity generation cannot be directly compared to the total amount of electric energy because they represent the chemical energy contained in the fossil fuels. I estimated the useful electric energy generated from these fossil fuel inputs by assuming a standard power plant efficiency of 40% as cited in the BP Statistical Review Methodology. [4]
| 1.073 × 1016 J y-1 × 0.4 | = | 4.292 × 1015 J per year |
Now directly comparing we find that
| 4.292 × 1015 J 4.245 × 1016 J |
= | 0.101 |
meaning only about 10% of the electric energy consumed in 2022 came from fossil fuels and the other ~90% came from renewables.
Uruguay has made significant progress towards a clean energy economy, particularly in the electricity sector. Fossil fuel use is in decline, but it is clearly still a significant source of energy for Uruguay and nearly 90% of fossil fuel energy is used outside of the electricity sector. While we can expect that the country's carbon footprint will continue to fall in coming years, it is important to see that even the greenest nations have a long road to fully decarbonizing their economies.
© Julio Contreras. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] "Green Energy Leaders," World Wildlife Fund, November 2014.
[2] N. G. Shannon, "What Does Sustainable Living Look Like? Maybe Like Uruguay," New York Times, 5 Oct 22.
[3] "Energy Balance 2022," Ministerio de Industría, Energía y Minería de Uruguay, 2022.
[4] "BP Statistical Review of World Energy 2022," British Petroleum, June 2022.