With the western United States now in its second year of a widespread drought, the extraordinarily low water levels at some of the critical reservoirs are adding a layer of uncertainty to electric reliability this summer.
The power generated from the West’s fleet of hydroelectric generating facilities is on pace to be much lower than normal during what could be a record hot summer. Some generators could shut down if water levels at reservoirs fall under certain thresholds needed for safe operation.
Lake Mead, the reservoir formed by the Hoover Dam in Nevada, has already fallen to the lowest level in its 85-year history, curbing the amount of power being produced to serve customers in Arizona, Nevada and Mexico, according to the Bureau of Reclamation Lower Colorado Region.
When full, the lake can hold 9 trillion gallons of water, a three-year supply for the states it serves. Earlier this month, the reservoir had fallen to only 200 feet above “dead pool” level, the point at which water cannot pass through the dam.
“We have a decrease of about 25% of our capacity in producing power because of the lower lake levels,” said spokesperson Patti Aaron of the Bureau of Reclamation Lower Colorado Region. The federal agency oversees water resource management in the region.
By August, the federal agency, which is the second largest hydroelectric power producer in the western United States, could declare an official water shortage.
In Oregon, snowpack in some parts of the state were at near or above-normal levels this winter. Since then, there’s been little to no rain, and the snowpack is gone.
Historically Low Water Levels
Meanwhile, California electric regulators noted that snowpack water content peaked at 60% of normal, similar to last year. However, this year’s snowmelt runoff has been earlier than a year ago, which also was earlier than normal. The California Independent System Operator (CAISO) said average water levels of large reservoirs for 2021 was about 70% of normal, which compared to 101% of normal in 2020.
The CAISO used Northwest River Forecast Center projections as an indication of potential imports into the state when planning for this summer. The Dalles Dam on the Columbia River in Oregon is generally used as a representative indicator. In May, the April-September reservoir storage projection was at 89% of average.
Several lakes in California are also recording historically low water levels. Lake Mendocino in Northern California could be empty by the end of the year, officials aid. Lake Oroville, the state’s second largest reservoir, is at around 40% of average. Some projections have the lake falling below 640 feet by late August. At that level, one of the three storage and pumping facilities it serves, the Edward Hyatt Powerplant, would have to be shut.
“Runoff this year in key mountain watersheds remains on a par with that of 2014 and 2015, the two warmest and driest years of California’s last drought, despite this year’s statewide April 1 snowpack being at 59% of average as compared to 25% of average in 2014 and 5% of average in 2015,” the California Department of Water Resources said.
‘Cautiously Optimistic’
Although hydro makes up less than 2,500 MW of the more than 30,000 MW of installed capacity in the state, CAISO accounted for the lower output from those facilities in its electricity planning for this summer.
“We were under the assumption that there would be lower-than-normal hydro conditions,” spokesperson Anne Gonzales said. “We noted that some of those lower hydro levels would affect us in the latter part of summer.”
Imports, typically from baseload natural gas plants, are expected to play a “substantial role” in reliability this summer, according to the CAISO. Natural gas also makes up more than 40% of the in-state power generation.
There are also about 2,000 MW of additional, readily available resources coming online to serve net peak demand. This includes battery storage that is expected to absorb excess renewable energy in the middle of the day, and inject it back into the grid after sunset when solar generation goes offline.
“New resources are coming online by summer, and we have taken the lessons learned from last year to make modifications to our market and operations,” CAISO CEO Elliot Mainzer said. “This makes us cautiously optimistic that there will be enough electricity to meet demand this summer.”
For two days last August, the grid operator implemented rolling blackouts to meet demand. Power loads are expected to be roughly the same this year, but CAISO said extreme heat events are becoming more likely.
“By incorporating last August’s historical heat wave into the assessment, it pushes weather previously regarded as extreme into what is now considered more normal ranges,” it said.
Planning For The Future
The Western Electricity Coordinating Council (WECC), which creates and enforces reliability standards across 14 states, two Canadian provinces and northern Baja Mexico, also acknowledged that the extreme heat and persistent drought conditions are prompting discussions on resource adequacy. The WECC collaborated with the North American Electric Reliability Council to create guidance for regional entities following the heatwave last August.
“We also perform short and long-term assessments to ensure entities have the appropriate planning tools and assumptions,” said WECC’s Julie Booth, manager of communications and outreach.
The Northwest PowerPool Corp., a voluntary association of Pacific Northwest-based utilities, also is developing a regional resource adequacy program to evaluate future capacity needs and pool resources to serve demand during stressed grid or market conditions.
Already this summer, the Bonneville Power Administration (BPA) has seen a decline in hydro output. The agency is the federal nonprofit provider of about 28% of the electric power used in the U.S. Northwest. In mid-May, hydro generation within the BPA territory was above 11,000 MW. It soared as high as 13,000 MW in the first week of June but has since declined, falling below 10,000 MW by the middle of the month.
The reduced hydro output comes as the region is bracing for the most grueling heat in decades. The National Weather Service (NWS) said temperatures could break records beginning June 27, with the scorching conditions set to linger for days. Daytime temperatures in cities such as Portland, OR, and Seattle were forecast to approach 110 degrees, breaking all-time high records. The extreme heat also was forecast to drift toward Idaho and Montana, approaching highs of 110 degrees, according to NWS.
Worsening Drought
Meanwhile, the U.S. Drought Monitor (USDR) indicated on Thursday that conditions continued to worsen after a hot and dry week. A few areas of drought in south-central and southeast New Mexico saw some “slight improvement” because of several rain and thunderstorm events in the last month.
“Unfortunately, widespread severe or worse drought continued in New Mexico, and conditions remained the same or worsened elsewhere,” according to the USDR. The monitor is produced jointly by the National Drought Mitigation Center at the University of Nebraska-Lincoln, the National Oceanic and Atmospheric Administration and the U.S. Department of Agriculture.
The drought map showed increases in moderate, severe, extreme (and in a few cases, exceptional) coverage in Colorado, Montana, Utah and Wyoming. Severe drought also expanded in western Idaho.
By the fall, wetter weather is expected to offer a bit of a reprieve in the West. The Pacific Northwest and California could be due for a pattern of summer storms known as the Southwest Monsoon. However, the so-called monsoon has been anything but for the last two years as 2020 was the driest and hottest on record.
The NWS said a lack of ability to predict the placement and strength of the subtropical high, which sets up near the Four Corners each and every summer, makes it difficult to predict how much rain may arrive. As of June 10, weather models showed various degrees of near average precipitation for July, August and September for western and central New Mexico, with slightly below to below-average precipitation east.
Given that polar regions are warming at a faster rate than the tropics because of climate change and causing the westerlies/polar jet stream to weaken, near-average precipitation during July, August and September is getting “harder to come by” in New Mexico, according to NWS. “An average monsoon may be a thing of the past.”
International Concerns
The dry conditions are not only a concern in the United States. Brazil is in the thick of its worst drought in more than a century, wreaking havoc on the country’s hydro power, which supplies nearly two-thirds of its electricity
Average water levels in the affected dams’ reservoirs in Brazil have fallen by more than 30%. The decline in hydro output has resuscitated liquefied natural gas (LNG), with imports up 60% in Brazil, according to consultancy Timera Energy.
NGI calculations indicate that a total of 54 U.S. cargoes had gone to Latin America this year. Brazil has made up the bulk at 20, followed by Chile at 13.5. Still, with the Southern Cone winter ramping up in June, these numbers are set to rise. New rules in the gas market that have allowed for competition along with a robust infrastructure buildout have also facilitated Brazil’s LNG demand.
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June 26, 2021 at 07:08PM
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'Substantial Role' Seen for Natural Gas as Extreme Drought Crippling Western Hydro Generation - Natural Gas Intelligence
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