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Last updateTue, 18 Sep 2018 1pm

Gov. Jerry Brown made international news when he vowed to fight President Donald Trump’s attempts to cut America’s climate-change research and rescind the nation’s commitment to the Paris Agreement.

Brown’s commitment to fighting climate change seems real, and under his leadership, his state has engaged in numerous greenhouse-gas-reduction plans. But there are caveats to his commitment, including the continued growth in fossil fuel extraction in California, and the state’s near-explosive population growth—both of which drive emissions up, not down.

There’s another issue that California needs to address: methane emissions from hydropower, particularly at Hoover Dam, the source of a significant portion of Los Angeles’ electricity.

About 25 years ago, a small team of scientists in Brazil started measuring the methane produced at hydropower dams and reservoirs. Led by Philip Fearnside, the scientists found surprising results, indicating that hydropower dams and reservoirs in tropical countries like Brazil emit high levels of methane—sometimes as much as a coal-fired power plant. Fearnside referred to these hydropower producers as “methane factories.”

The studies have multiplied over the last two decades, and in 2006, the Intergovernmental Panel on Climate Change included calculations for measuring “Methane Emissions From Flooded Land” in making national greenhouse-gas inventories. Since 2006, study after study has confirmed high levels of methane emissions from dams and reservoirs, and when the Environmental Protection Agency measured methane emissions from a reservoir in the Midwestern United States in 2016, the emissions detected were as high as those measured in the Brazilian hydropower plants.

In September of last year, an international team of scientists synthesized dozens of studies around the globe and found that hydropower’s methane emissions have been dramatically under-measured. This analysis, published in Bioscience and funded by the Army Corps of Engineers, the EPA and U.S. National Science Foundation, made international news with its conclusion that the Intergovernmental Panel on Climate Change needed to revise its calculations and include hydropower’s significant emissions in its climate change scenarios.

Another study, published in September 2016 by a team of Swiss scientists, used previous measurements at dams and reservoirs around the world to create a model that estimated methane emissions from nearly 1,500 hydropower plants and other dams and reservoirs across the planet. The study’s conclusions further rocked the climate-change world: Climate-change emissions from Hoover Dam and Lake Mead on the Colorado River near Las Vegas were found to be about equal to those of coal-fired power plants that produced the same amount of electricity.

Why do dams and reservoirs produce emissions like methane? The answer is that when organic material such as vegetation, sediment, algae and other runoff decomposes underwater at a reservoir, methane is released. This is a natural process called “anaerobic decomposition,” but it is dramatically intensified in dam and reservoir systems that are not natural lakes. Take Hoover Dam and Lake Mead as an example. Lake Mead is enormous—about one-quarter the size of Rhode Island. The reservoir level fluctuates over the year, causing many square miles of its banks to periodically dry up, grow vegetation and then get flooded again each year.

Large amounts of sediment are also washed down the Colorado River every year. This sediment coats the bottom of the lake and also dries up along the miles of caked mud on the lake’s hot banks. Thus, Hoover Dam and Lake Mead work together to create a high-methane-producing hydropower system. Even though measurements and estimates of methane are very recent, as far back as 1948, the U.S. Geological Survey was examining what it was then called “gas pits" in the mud flats of Lake Mead.

About 50 percent of Hoover Dam’s electricity is wired to the Los Angeles area. Yet no greenhouse gas emissions calculations—in Los Angeles or statewide in California—include Hoover Dam’s contribution. That’s like having a large coal-fired power plant burning in downtown Los Angeles whose climate change impact is completely ignored.

California has 1,400 dams and reservoirs. Most of them produce far less methane than Hoover Dam, but many of those dams’ emissions are neither estimated nor measured. It’s time for California to acknowledge its methane emissions from hydropower, measure them—and, finally, offset or stop them.

Gary Wockner is a contributor to Writers on the Range, the opinion service of High Country News, where this piece first appeared. He is the director of the Save the Colorado River Campaign and the author of River Warrior: Fighting to Protect the World’s Rivers.

Published in Community Voices

The water-energy nexus spans the world of electricity generation and water movement, particularly in Western states. It takes water to produce steam for coal, natural gas and nuclear power plants, and they usually need water to cool them down. Huge amounts of electricity are needed to pump water across the desert; the Southern Nevada Water Authority is Nevada’s biggest user of electricity, and the Central Arizona Project relies heavily on the Navajo Generating Station to keep water moving through the canals.

Surely the most obvious link between water and energy, and between climate and electricity generation, though, is found at the West’s numerous hydroelectric generation stations, and here in California—deep in a nasty drought—we’re feeling that link in a painful way.

The relationship is pretty simple: More water in a reservoir or river equals more potential for generating electricity by releasing that water to turn turbines. All of California’s reservoirs are far below the average levels for this time of year. New Melones reservoir is sitting at just 17 percent of capacity; Shasta reservoir, one of the state’s biggest hydroelectric power plants, is only 49 percent full. Meanwhile, Lake Mead and Lake Powell, backed up behind the Southwest’s two biggest hydropower plants, are at critically low levels. This is impacting electricity generation, without a doubt, and doing so during the hottest months of summer, when the grid is already stressed.

We wanted to get a more concrete sense of exactly how the drought is affecting hydropower generation in California and beyond, so we dug into the data and crunched some of the numbers. The map below in the “Media” field gives a rundown on the biggest hydropower generators in the Southwest, including all of California’s plants with a generating capacity of 200 megawatts or more, along with Glen Canyon Dam, Hoover Dam and Davis Dam on the Colorado River. Click on the icons, and you’ll see a graph of power generation from 2009 through 2014.

Here are the highlights of the number-crunch.

In California, drought has taken a direct hit on hydropower generation, as is quite evident in the map below, and the graph above. In 2014, California’s collective hydropower plants kicked out about 17 million megawatt hours of juice. Not bad, except that it was only about one-third of what they produced in 2011, an unusually wet year, and about half of an average year in pre-drought times.

The average home uses about 11,000 kilowatt hours of power—or 11 megawatt hours—each year. In other words, something like 2.8 million fewer homes were powered by hydroelectricity in 2014 as compared to 2011 in California. And things have only gotten worse since.

The good news is that burgeoning wind and solar in the state have stepped in and taken up some of the slack. The bad news is that more natural gas power has also been needed to fill the deficit.

Drought diminishes hydropower production from Colorado River dams as well, though, as directly as in California. Hoover Dam is a huge hydroelectric power plant, with a nameplate capacity as large as some of the biggest coal-fired power plants, and its “fuel” supply is running out as Lake Mead reaches historically low levels. So it’s no wonder that folks are concerned about its status as a power producer. So far, though, drought hasn’t had as severe an impact on hydropower production here or in Glen Canyon and Davis Dams, above and below Hoover, respectively. That’s because the operators of these dams can’t withhold a bunch of turbine-turning water just because their reservoirs are running on empty. In fact, Hoover dam’s turbines produced 33,000 more megawatt hours of power during the first quarter of this year, even as it approached record low levels, than during the first quarter of 2014. Yet dry times still do impact hydropower production, because the lower the reservoir, the less force the water has to turn the turbines. Lake Mead’s “dead pool”—the level at which it could no longer turn the turbines—was once 1,050 feet, about 25 feet below what it is now (and a level that is not in the cards at least for a few more years). But new wide-head turbines have been installed over the last decade, which lowers dead pool to about 950 feet, thus extending Hoover’s hydropower life for a while.

Hydroelectricity is an especially valuable form of power. Hydro is a good source of baseload power, meaning it can put a steady stream of juice into the grid around the clock. But it’s also valuable in that grid operators can crank it up or down relatively quickly, meaning it can be used to balance out variable power sources like wind and solar, or it can step in to account for a sudden surge of power demand, due to everyone turning on their air conditioners in the hottest time of the day, coupled with a drop in solar generation as the sun dips toward the horizon. It’s in this capacity that Hoover and Glen Canyon are huge assets to the southwestern grid.

If drought-induced hydropower loss is going to happen anywhere, though California’s a good place for it. If any other state lost tens of millions of megawatthours of power from one source, they’d likely replace it with coal-fired power. But California is fast on its way to completely phasing out coal, and it’s also under the most robust renewable portfolio standards, so it can only get so dirty when looking for a stand-in for hydro.

Jonathan Thompson is a senior editor of High Country News, where this story first appeared

Published in Environment

When the Hoover Dam was built in 1936, it was the largest concrete structure—and the largest hydropower plant—in the world, a massive plug in the Colorado River, as high as a 60-story building.

For nearly 80 years, the dam has been producing dependable, cheap electricity for millions of people in the Southwest, but as water levels in Lake Mead continue to drop, the future of “the greatest dam in the world” is more precarious than it ever has been, and utilities across the desert—including local power provider Southern California Edison—are taking notice.

Lake Mead, the 112-mile reservoir created by the dam, was recently projected to hit 1,074.73 feet above sea level, the lowest it has been since it was filled in 1937. Thanks to a 16-year drought and serious over-allocation, Lake Mead is now just 37 percent full. Although a “miracle May” of rain means the water level will rise again, the longer term prognosis is more worrisome: If water levels continue their downward trend, the amount of energy generated by the Hoover Dam will fall, leading to higher electricity costs for 29 million people in the desert Southwest.

That's because a shallower reservoir means less water pressure against the turbines, generating less electricity. A recent report by graduate students at the University of California, Santa Barbara, in conjunction with the Western Water Policy Program, examines the economic and physical impacts as Lake Mead’s elevation falls: With each 25-foot drop, total energy costs increase by roughly 100 percent, compared to a full reservoir. The costs paid by contractors for hydropower double at 1,075 feet, triple at 1,050 feet, and quadruple at 1,025 feet. At 895 feet, the turbines won’t run—a level they call “dead-pool.”

Dead pool is not imminent, and in the short term, less generation at Hoover won’t translate into soaring electrical bills, says Frank Wolak, an economics professor at Stanford. That’s because utilities buy “futures” contracts for energy, which guarantee a certain price for a period of time. It’s like buying a plane ticket in advance: The price is significantly less than one bought on the same day as a flight. In the case of Hoover, many of those contracts span up to 10 years and were negotiated before low water levels became a significant concern.

Still, Hoover’s power capacity has dropped nearly 25 percent since 2000, and the 53 hydropower facilities run by the U.S. Bureau of Reclamation across the West are producing 10 percent less power than a few years ago, despite rising demand. So when those futures contracts run out—and continued low water levels appear likely—bottom-barrel prices for hydropower will likely be a thing of the past.

That means that utilities currently relying on Hoover’s power, such as the Overton Power District No. 5, which serves 15,000 people in Nevada on the southern end of Lake Mead, are wary. Overton buys 20 percent of its power from the Hoover Dam, 5 percent from other hydro projects, and 75 percent on the spot market (where energy is traded on day-by-day basis). The utility anticipates having to replace 5 percent of its hydropower with another, more-expensive energy source, says Mendis Cooper, Overton’s general manager. That switch won’t translate into sky-high energy bills, likely just a 1 to 2 percent increase. But if Lake Mead continues to fall, and shortages become routine, his customers could see more dramatic increases in their electricity bills. 

“We’ve been having those discussions,” Cooper says, noting that the major topic is moving to more renewables, like solar, as well as improving efficiency.

Luckily, the West has ambitious renewable goals, says Wolak, which will likely make up more of the region’s energy mix and help mitigate the loss of hydropower in the future.

Still, renewables aren’t a panacea. Wind and solar are far more volatile and require backup power sources, such as gas-fired power plants. And though the prices for renewables have come down in recent years, they’re still no match for cheap, federally subsidized hydropower.

“They solve the resource issue,” Cooper says, “but not the price issue.”

Sarah Tory is an editorial fellow at High Country News, where this story first appeared.

Published in Environment