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| Fig. 1: Energy usage percentage by section in California, 2012. [1] (Image Credit: C. Hong) |
California is a state located in the west part of the United States adjacent to the Pacific Ocean. It is currently the No.1 energy consuming state in the whole United States. Although still mostly powered by fossil fuels, there is already a significant difference in energy usage percentage by section in California now (2021) than that ten years ago (2012).
Fig. 1 shows California's energy usage percentage chart in the year of 2012, as reported by the EIA. [1] From the chart, energy from coal, petroleum and natural gas is 0.66%, 46.7% and 37.3%, respectively. After summing the above three sources together, as a whole, fossil fuels occupy 87.87% of California's energy use. All renewables account for the rest 12.13%, with nuclear, hydro, biomass and geothermal being 2.94%, 3.87%, 4.5% and 1.84%, respectively. One fact to notice is that two of the most popular renewables, solar and wind, only account for 0.8% and 1.41% of the total energy use in 2012, respectively.
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| Fig. 2: Energy usage percentage by section in California, 2021. [2] (Image Credit: C. Hong) |
Fig. 2 shows California's energy usage percentage chart in the year of 2021, as reported from the EIA. [1] From the chart, energy usage from coal, oil and natural gas is 0.42%, 44.5% and 32.5%. Fossil fuels altogether account for 77.42% of California's energy supply. The remaining 21.06% comes from all sorts of renewables, with nuclear, hydro, biomass and geothermal being 2.56%, 1.94%, 7% and 1.51%, respectively. Solar and wind account for 7.52% and 2% of California's energy supply in 2021.
A few interesting observations can be made after comparing these two charts. One thing is that for coal, oil and natural gas, the energy usage percentage for each of them has a small drop from 2012 to 2021, meaning that people are using fewer fossil fuels. As a whole, it drops from 87.87% in 2012 to 78.94% in 2021. In terms of renewables, the total energy usage percentage almost doubles between 2012 to 2021 (from 12.13% to 22.58%). For some renewables such as nuclear, hydro and geothermal, there is a decrease in energy usage percentage. This might be due to security reasons or exploitation. The percentage for wind stays relatively stable. However, the use of biomass increases a lot, from 4.5% to 7%. The most exciting thing is related to solar power. During the ten-year period, the energy usage percentage for solar increases by almost 10 fold, from 0.8% to 7.52%.
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| Fig. 3: Future California energy usage. (Image Credit: C. Hong) |
Recent research finds that the total power of a rooftop solar panel can reach up to 5000 W. [2] According to the San Francisco Chronicle, the total population in California is 39 million. [3] Assume a house occupies an average of 3 residents, there are approximately 13 million houses in California. Installing more rooftop solar panels can be one of the many energy solutions in California in the future. Assuming an additional 30% of home owners in California agree to install solar panels , and assuming each home has 2 panel systems, the total energy produces from these panels is 4.12 × 1017 J per year(See calculations below). California's total annual energy consumption did not vary a lot between 2012 and 2021, roughly 7400 billion BTUs, which is equivalent to 7.8 × 1018 J. [1] Therefore, new installed solar panels can account for about 6% of California's total energy consumption in 2021.
| Energy per year | = | 5000 Watts panel-1 × 2 panels household-1 |
| × 1.3 × 107 households × 0.3 | ||
| × 3600 sec h-1 × 8 h d-1 × 365 d y-1 | ||
| = | 4.10 × 1017 J |
Fig. 3 presents a scenario of what California's energy usage percentage may look like in the future based on the calculations above, assuming the solar panels are successfully installed and come into use. Also, another assumption to make is that energy percentage for others, which is nuclear, hydro, geothermal, biomass and wind, stay relatively stable. According to the figure, energy percentage of solar further increases from 7.52% (2021) to 13.52% (future), which is another big step in terms of renewables. In terms of fossil fuels, the total energy usage percentage of fossil fuels will keep declining, from 84.66 (2012) to 77.42 (2021) to 71.47 (future).
Although the shift may be slow and not that obvious, California is indeed moving towards to a greener energy campaign. Reliance on fossil fuels is diminishing year by year between 2012 and 2021, and may be further diminished in the near future. There is never a silver bullet that can solve all the problems altogether. Rather, it is a mixture of all the existing and future techniques. Therefore, working hard and being optimistic are crucial in order to bring California towards the campaign!
© Chunchen Hong. 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] "State Energy Consumption Estimates 1960 through 2021," U.S. Energy Information Administration, DOE/EIA-0214(2021), June 2023, pp. 83-84.
[2] K. Atluri et al., "Performance of Rooftop Solar PV System with Crystalline Solar Cells," 2018 National Power Engineering Conference (NPEC), IEEE 8476721, 9 Mar 18.
[3] N. Sumida, "Charts Show Extremely Detailed Look into California's Changing Population," San Francisco Chronicle, 11 Oct 23.