Note: The U.S. Department of Energy has just released the statistics for our energy use and generation thru 2019. I thought you might be interested in reading the following analysis.
*U.S. Renewable Energy Sources - Their Real and Potential Output* By: Stan Jakuba, MSc. April 2020 *In graphs and numbers, this article provides an overview of energy generation in the U.S., particularly electricity, during the last two decades. The data are extracted from the annual reports of the Department of Energy**.[1**]** For convenience, the various units used in the DoE tables are converted here to just one unit, the watt (*W*), with its billion multiple, the gigawatt (*GW*). The same unit serves for both generation and consumption, a feature that enables straightforward comparisons among various efficiencies, capacity factors, site factors, and the like. A reference to tables of conversion factors for units such as *Cal, cal, joule, Btu, Wh, *each per second, hour, or year is at the end.* * The Department of Energy (DOE) lists six significant sources of renewable energy: Wind, Solar, Hydro, Wood, Waste, and Geothermal. Among them, solar represents the output of both photovoltaic (PV) and concentrated-solar (C-S) plants. The following pages discuss the up-to-date electricity production of those six sources. In numbers, they estimate the likelihood of the renewable sources powering our society’s future needs. The energy generation obtained from the six sources during the last two decades is illustrated in the two graphs below: Wind and Solar (W&S) on the left, and all the others, Hydro, Wood, Waste, and Geothermal (H&W&W&G) on the right. All sources but geothermal provide only one form of energy, electricity; geo yields also heat but its amount is insignificant in the US). A quick glance at the charts reveals the upward trends in the left graph and the near horizontal, no-growth trends in the right one. The scales are the same in both charts. Notice the lowering rate of growth lately, those less steep lines with wind and, even more so, with solar. The flattening is due to the efficiency loss of the existing plants with age, and due to the portion of the new ones just replacing the aging ones, typically every 20 years. Next are the details of the respective yields of all renewable source, starting with W&S, those two sources being the only ones whose output has been growing. *Wind and Solar Production* In 2019, wind plants’ production rose by 2.6 GW reaching 34.2 GW, and solar added 0.6 GW reaching 8.2 GW. That combined wattage of 42.4 GW represents 9 % of the overall U.S. electricity generation of 463 GW from all electricity sources in the US. Using this 2019 annual rate of growth, it would take 131 years for W&S to reach the above overall number. Actually longer as these numbers imply no growth in consumption, a trend which is unlikely considering population growth, adoption of electric vehicles, robotization of the industry, and the desired increase in living standard of everybody. The U.S. primary energy consumption was 3230 GW, of which perhaps 60 % is waste heat from thermal plants and thus can be subtracted for these comparisons. That lowers the overall amount to approximately 1500 GW. It would take a century and half to cover that amount, and that is without considering the growing demand mentioned just above. These long-term projections for the W&S output would, of course, be realistic only if some large-scale storage technology existed, one that is also relatively low-cost, inasmuch as W&S electricity alone is already many times costlier to the consumers than that produced in the traditional plants of today. As an example of that cost, a 1970s nuclear plant[2] operates at 2.4 $/W, the dollars adjusted for inflation and the wattage reflecting the power delivery over four decades. In comparison, an off-shore wind farm[3] averaged 21.0 $/W cost over two decades. That represents nine times higher cost, all conditions the same. The nuclear plant is still running in its fifth decade, at full power day and night, year round. The wind turbines are being dismantled after the usual two decades, their performance diminishing towards the life end. This ten times higher cost of wind electricity production has not impacted customers as yet thanks to the plethora of subsidies and incentives, paid for by taxpayers, and the mentioned disregard for the cost of dismantling, scrapping and disposing responsibly of all that metal and plastic. Surprisingly, that cost is not much different from the cost of fabricating and erecting the towers. Statistics show that if there had been any lowering in electricity cost, there was the ever cheaper natural gas was behind it. As to the cost of operating the plants, the W&S industry claims employment already higher than either the gas or coal extraction industry at about 250 000 jobs. The relative productivity per employee is 7.5 kW with solar, 32 kW with wind, 1300 kW with fossil fuels, and 2000 kW with nuclear[4] The chart at the very end shows the employment in the solar industry alone exceeding the job numbers in either oil and gas extraction or coal mining. Do the math - the presently available total workforce will be insufficient to manufacture, erect, operate, maintain, tear down, and dispose of all those millions of W&S plants that would be needed anew five times a century to fully power our society. Most of us would work for the W&S industry, its operators, suppliers, contractors, maintenance, line crews, wreckers, etc. And we should recognize that jobs are a labor cost that raises the electricity cost to customers. Employing robots instead, as has been suggested, implies more energy needed which requires more W&S plants to generate it, which requires more …... (you got it). Besides, jobs are a cost and not benefit if economics matter. Employees and contractors can do other things besides manufacturing, erecting, manning, dismantling and disposing of W&S plants. *Non-W&S Renewable Sources:* Referring to the preceding right-hand-side graph, the near-horizontal-trend lines there show no worthwhile upward trend in the waste, wood, geothermal output in the two decades, stagnating at 9.1 GW. Hydro registered its usual ups and downs, ending at 33 GW this year. The combined yield of all four sources is not any higher today than it was two decades ago; actually, it is slightly less. What is the chance for a gain? Let’s start with hydro: Increasing hydro’s yield would require either more rain or reduced irrigation. (Dams sometimes serve both power and irrigation purposes.) The rain is beyond our control. Regarding irrigation, are we willing to cut down on domestic-grown veggies? There are proposals for building more dams, or equip current irrigation and flood control dams with turbine-generators. But there is a limit for the number of sites suitable for damming and some of those could not be built because of environmental concerns. The retrofitting offers too low a return on investments, if any, which is why engineers in the past did not equip the dams with generators when it would have been much cheaper. And that was at times when electricity was more expensive and environmental restrictions fewer than today. The builders undoubtedly considered also silting, the ultimate death of all dams, and a rather quick one with the small ones. The three remaining “Other” sources, wood, waste and geothermal (W&W&G) provide steady supply from year to year, unlike the wiggling hydro, but it is minuscule in comparison. Besides, although wood and waste are renewable sources they cannot be classified as clean: their burning emits CO2 as well as “real” pollutants such as those that one can smell. Thus the legitimate, clean, sources in the “Other” category are just two: hydro and geothermal; they yielded 33+2=35 GW in 2019. That output inevitably will continue averaging at the same level for the foreseeable future. *What then is the prospect for meeting the 100 % clean energy goal in this country? * To achieve that, W&S would have to be generating roughly *hundred times* the present generation. Should electric cars become ubiquitous, they alone would be consuming another 110 GW[5] increasing the total for the country to 573 GW. Theoretically, it should be possible to surpass current W&S output by 100 %; however, the high cost of doing so would bring dire consequences for the U.S., to what purpose? And it would actually take longer, because the DOE/EIA numbers are not quite correct; their yields are too high. They do represent the values reported to the Department by each utility all right, but those numbers have not been corrected for the input-energy that all sites receive from the grid and from fossil fuels. This external feed is needed nightly and cloudy-days with solar, and, with wind, when it blows too little or too much. Then there are also the maintenance and repair interruptions. During all those times the site consumes energy that comes from the grid or other energy sources. That amount should be subtracted to provide true yields. As an example of this reverse energy flow, a CSP[6] in Mojave desert drew about 9 % of its output from the grid and from burning natural gas, diesel fuel, propane, gasoline, aviation fuel (helicopters) and the like. Such draw is rare with nuclear and other thermal plants and also insignificant on the scale of the incomparably higher output per site. Adjusted accordingly, the corrected DOE numbers for renewable sources would be several percent lower than those two graphs show them. How much depends on the productivity of each site individually; that information is not only too difficult for me to obtain, but it may differ among information source such as be adjusted for political correctness with some. This needed downwards correction is best reflected in the so called *Site Factor* (SF). SF is a ratio akin to the *Capacity Factor* (CF), but whereas CF is the ratio of the *plant’s actual output *averaged over its whole life* to its name plate power* rating, the SF is the ratio of the *plant’s input energy *from all external sources* to the output *of the site. As each plant deteriorates with age and use, its CF is declining and the SF growing. Eventually, the CF and SF would get to the point where the site just powers itself. No net output. An operation at this point in time should list zero output and negative numbers beyond that. But the fact is that essentially all energy statistics worldwide list the output as if each plant consumed zero outside energy in its existence. That custom was established when thermal plants ruled; their SF was, and still is, negligible. Thus the unpopularity of this criterion with renewable sources. But, for a fair comparison among different types of plants and different sites, the SF and its value should be recognized and it should be included in the DOE/EIA reports. And yes, it is difficult to find the data for the energy input to the plant. Most site managers do not know it themselves. The data should include all forms of energy, not just electricity, such as the heat from fossil fuels. If you know of a good way to search for this info, please let this author know. *Feasibility of 100 % Energy from Renewable Sources* Over $3 trillion has been spent on the renewable energy effort since 2004, and the figure has now stabilized at about $300 billion for each one of the last six years.[7] For a cost comparison, the earlier mentioned nuclear power plant - another source of clean and green electricity and also heat - cost $4 million, inflation adjusted. Not billions, just millions. Thousands of them could have been producing power for the money spent on renewables today, making our country and the world cleaner and richer as a result. As to the likelihood of the W&S output influencing climate change, those less than 10 % of electricity, which is 1 % of total U.S. energy consumption, is unlikely to do so. Besides, we have no means of measuring such causes and effects reliably as yet. Despite this discouraging renewable energy history, documented numerically in voluminous literature, it is politics, not economy, that forces our country and individual states continue year after year to commit us, the tax- and rate- payers, to the goals of “20, 50, …. 100 percent of energy to be derived from clean, renewable sources in 5, 10 …. 20 years.” That, despite seeing those goals not met and budgets going red repeatedly for a half a century by now. And some proponents claim this energy to mean the US energy overall not just the electrical portion of it. That raises the target sevenfold. ---------------- *A note on the units in the DoE annual statistics: Those pages list different units for different kind of energy and power thus making comparisons cumbersome and prone to errors. Unified in this report on just one unit, the watt (W) makes comparison instant and less prone to mistakes. For information, 1 GW = 8770 million kilowatt-hours/year and 30 quadrillion Btu/year. The “per year” is implied in the DOE tables, but not stated. This omission in the headings is one reason why there is confusion in converting power and energy numbers. Where just one unit, the watt, should suffice, there is also joule, calorie, Btu, …., and any of them per second, minute, hour, day, or year. Stanislav Jakuba, MIT ’70 References: [1] https://nam01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.doe.eia%2F&data=02%7C01%7CusMA%40lists.colostate.edu%7C21217344e23a4bb021d108d7d973223a%7Cafb58802ff7a4bb1ab21367ff2ecfc8b%7C0%7C0%7C637216960831648363&sdata=iAqX6sSGrE4XqRWX388UZBh9fbp5F6tWNECmgNSqijw%3D&reserved=0 Annual Energy Review [2] https://nam01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.millstone%2F&data=02%7C01%7CusMA%40lists.colostate.edu%7C21217344e23a4bb021d108d7d973223a%7Cafb58802ff7a4bb1ab21367ff2ecfc8b%7C0%7C0%7C637216960831648363&sdata=a9tOHJj8YMDhr9VEwz5ZSOw5yl1UstxL3UfHppKYu8k%3D&reserved=0 Nuclear Power Plant complex in CT [3] https://nam01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.vindeby%2F&data=02%7C01%7CusMA%40lists.colostate.edu%7C21217344e23a4bb021d108d7d973223a%7Cafb58802ff7a4bb1ab21367ff2ecfc8b%7C0%7C0%7C637216960831648363&sdata=ziagnDaORAr%2F722jeFndL2t0m84b%2FnjyVnMq7WseXnE%3D&reserved=0 Offshore Wind Farm, Denmark [4] https://nam01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.bloomberg%2F&data=02%7C01%7CusMA%40lists.colostate.edu%7C21217344e23a4bb021d108d7d973223a%7Cafb58802ff7a4bb1ab21367ff2ecfc8b%7C0%7C0%7C637216960831648363&sdata=nKPSQr9%2F9TmevcPRHMlDL2AyjbUzf9jxK1vgmjffoEM%3D&reserved=0: There Are More Jobs in Solar than Oil and Gas, Coal Extraction in the U.S. [5] https://nam01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.masterresource.org%2Felectric-vehicles%2Fenergy-usage-cost-gasoline-vs-electric&data=02%7C01%7CusMA%40lists.colostate.edu%7C21217344e23a4bb021d108d7d973223a%7Cafb58802ff7a4bb1ab21367ff2ecfc8b%7C0%7C0%7C637216960831648363&sdata=jSCewcYKvIdP836a5Yuug1HfVwmNcfMbyhXIQ5KKDac%3D&reserved=0 [6] https://nam01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.masterresources.org%2Fconcentratedsolarplant&data=02%7C01%7CusMA%40lists.colostate.edu%7C21217344e23a4bb021d108d7d973223a%7Cafb58802ff7a4bb1ab21367ff2ecfc8b%7C0%7C0%7C637216960831648363&sdata=1T7wynIgCKuHvXdnwqsK1%2FpKBvt%2FIFC78gKw2BC7s4w%3D&reserved=0 [7] https://nam01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.bnef.com%2Fdataview%2Fclean-energy-investement%2Findex.html&data=02%7C01%7CusMA%40lists.colostate.edu%7C21217344e23a4bb021d108d7d973223a%7Cafb58802ff7a4bb1ab21367ff2ecfc8b%7C0%7C0%7C637216960831648363&sdata=nBOWdA85OmTSx2f4bpVQm0ZVdOP9%2F5q3brC0R9SobMQ%3D&reserved=0
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