Part 9 of the excellent series on California water policy from California Globe.
An excerpt.
“In May 1957, Harvey Banks, then director of the California Dept. of Water Resources, submitted “The California Water Plan” to the governor and state legislature. On page 14 of part one of this comprehensive document, Table 3 depicts what Banks and his team determined to be the “Estimated Present and Probable Ultimate Mean Seasonal Water Requirements.” The scale of their ultimate expectations reveals the magnitude of the challenge they had accepted.
“At the time, the estimated statewide water requirements were 19.0 million acre-feet (MAF) per year for agriculture, which they estimated would ultimately peak at more than double that amount, 41.1 MAF/year. The total urban and miscellaneous use per year at the time was 2.0 MAF/year, which they estimated would eventually quintuple to 10.0 MAF/year. In all, California’s mid-century water planners intended to build infrastructure capable of delivering to farms and cities 51.1 million acre-feet per year.
“This is a fascinating statistic, because this ultimate goal, set 65 years ago, easily fulfills the goal anyone might set who wishes to realize water abundance in California today. As we have seen, the average total water use in California in recent years for farms and cities was 41.6 million acre feet per year, well short of the 51.1 MAF goal set by Harvey Banks and his team back in 1957.
“A examination of what they intended to build in order to accomplish this objective back then, compared to how it could be possible today, can uncover encouraging insights. To view this grand conception, refer to Table 30 on page 212 (ref. part two) of the original Water Plan, “Summary of Features, Accomplishments, and Costs of Physical Works Under the California Water Plan.” Or, for a summary of this summary, refer to the following table.
“The 1957 Water Plan called for construction of 376 new reservoirs to be in addition to those already built. These new reservoirs were planned to add 76.9 million acre feet of new storage capacity with an average annual yield of 24.0 million acre feet. The other primary element of the 1957 Water Plan was to rely on interbasin transfers via an astonishing array of new conduits. These included 4,987 miles of canals, 680 miles of pipe, and 598 miles of tunnels.
“The attentive reader will note that gigawatt-years is referenced on the summary chart above, instead of “millions of kilowatt-hours,” which appears on the source document. This unit of energy, gigawatt-years, is an underutilized but very useful point of reference. Its utility comes into focus when anyone attempts to determine the yield of an energy project. It makes it very easy to compare capacity in gigawatts (or megawatts), which is a common term used to report how much energy flow can be produced or consumed by a project when running at maximum output, to how much of that capacity is actually used (or produced) by a project over a period of time. In the above examples, it can be seen that the new hydroelectric dams included in the 1957 Water Plan could have collectively generated an electricity flow of 7.9 gigawatts if all of the reservoirs had sufficient water to spin all the turbines, all the time, in all of the power houses. But given the amount of projected rainfall and timing of releases from these dams, the planners expected them to annually produce only 3.9 gigawatt-years of energy. By normalizing these two measurements – flow of energy, and units of energy – to gigawatts, it is easy to see that the planners expected a yield of 49 percent (3.9/7.9). In their report, the planners projected a yield of 33,767 million kilowatt-hours, rendering it impossible for anyone viewing that table to intuitively assess the yield of these planned projects. One gigawatt-year is 8,766 million kilowatt-hours. Do that in your head.
“If the goal of public policy discussions is to come up with rational public policies, the choice of units matters. For example, when viewing “nameplate capacity” on solar or wind installations, the amounts are typically reported in megawatts, and the yields are then reported in megawatt-hours. Without a calculator, this offers no insight into the yield of these devices. But when a solar or wind farm is installed with a reported output capacity of, for example, 500 megawatts, and the projected annual energy production is reported at 100 megawatt-years, one knows immediately that the yield is 20 percent (100/500). One megawatt-year is 8,766 megawatt-hours (365.25 x 24). More on this later.
“In specific reference to California’s water infrastructure, normalizing these variables also makes it easy to compare the estimated annual energy yield from the planned hydroelectric dams (3.9 gigawatt-years), and the estimated annual energy consumption of the planned pumps (5.6 gigawatt-years), to the total electrical generation in California. In 2018, according to data compiled by the Lawrence Livermore Laboratory, California generated 1,700 trillion BTUs of electric power, which equates to 57 gigawatt-years (1,000 trillion BTUs equals 33.4 gigawatt-years). This is interesting. Had the 1957 Water Plan been fully implemented, today those new pumps would be consuming an amount equal to 10 percent of California’s entire electricity consumption today (5.6/57), offset by planned hydroelectric generating capacity that may have given back an amount equal to 8 percent of California’s current electricity consumption (3.9/57).”
To read the rest, The Abundance Choice, Part 9: Can Reservoirs be Part of the Solution? – California Globe
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