How many gallons to run that microwave?

Lauren Sommer / KQED

A natural gas power plant in Long Beach that uses "once-through" cooling.

We hear a lot about how green our energy is in California. Instead of using coal, the state runs on natural gas and increasingly, renewable power.

But there’s a hidden cost to our energy supply: water use. In fact, every time you turn on a light, it’s like turning on your faucet. It’s been calculated that it takes 1.5 gallons of water to run a 100-watt light bulb for 10 hours.

The way water and power work together is a lot like a tea kettle. Steam drives the power industry.

How Power Needs Water

You can see it at the Gateway Generating Station, a natural gas power plant in the northeast Bay Area. The plant looks complicated but making power is pretty simple. Step number one: burn natural gas. That produces a lot of heat.

“You’ve got 1,700-degree exhaust energy, or waste heat,” says Steve Royall of PG&E, who is giving me a tour through the maze of pipes and compartments. The heat hits pipes that are filled with water and the water is boiled off to create steam. That’s step number two: make steam to turn a steam turbine, which is attached to a generator. It’s the water that’s making the power.

Source: National Renewable Energy Laboratory. Illustration by Andy Warner.

But water has another job in power plants. That steam, even after it makes power, is still hot. So, most power plants use water to cool it down. “You’ve got to have the ability to cool everything down so the cycle can continue and your equipment doesn’t overheat,” says Royall. (Learn more about how power needs water in this illustration).

Nuclear plants and coals plants use water the same way, in some cases, millions of gallons a year. In fact, nationwide, power plants need more freshwater than farms do, according to a U.S. Geological Survey study.

Newer power plants reuse water, but a lot of it is lost to evaporation, which means it has to be replenished. “Typically water has been the most abundant resource available,” says Royall, “but as water resources become more valuable, it’s extremely important that we think about water use.”

Future of Water Scarcity

“There is a general understanding that the era of abundance is over,” agrees Heather Cooley of the Pacific Institute, an Oakland-based think tank focused on water issues.

“Water resources are limited and there is a growing demand. We have growing population in the West. We have a growing economy.”

And then there’s the climate – which is changing. “The climate models suggest that water availability will be more variable. So we’ll have wetter years, we’ll have drier years. We’ll have a smaller snowpack,” says Cooley. In some places, power plants are already feeling the effects of tightening water supplies.

Power plants can cut their water impact by using recycled water. “We can look at less water-intensive renewable energy systems. So looking at wind and at solar panels,” says Cooley.

But it turns out, some renewables need water, too.

Solar Technology Grapples with Water Costs

In a parched corner of California’s Mojave Desert, construction equipment shimmers in the mid-day heat. These 3,500 acres near the Nevada border are the site of the Ivanpah Solar Project.

“The Ivanpah project, when it’s operational, will be the largest solar thermal project operating in the world,” says Joseph Desmond with BrightSource Energy.

You’ll notice he said “solar thermal,” a technology that’s different than the solar panels you see on rooftops. The plant is a huge field of mirrors that are specially angled to focus the sun’s heat at a tower, 400 feet tall.

“Inside the top of that tower is a boiler. All of the energy is then is used to create high temperature, high pressure steam in excess of 1,000 degrees Fahrenheit,” says Desmond.

That spins a steam turbine that makes electricity. Just like a natural gas plant, that steam has to be cooled back down, which is normally done with water. In the desert, it’s not easy to find. “You have to dig down, I want to say about 840 feet,” says Desmond.

The Ivanpah solar project under construction. (Photo: BrightSource Energy)

So, the Ivanpah plant will use a new technology called “dry cooling.” Instead of using water, the plant uses massive fans to blow air over the pipes of hot steam. “Air cooling allows us to reduce the water consumption by as much as 90%,” says Desmond.

But there’s a catch. Dry cooling uses more energy, so the plant’s not as efficient. It’s even less efficient when it’s hot out.

It also costs more to build. “It can range between one and five percent more. Now, that may not seem like a lot but when you’re competing and every penny counts, it’s an important factor,” Desmond says.

Three of the seven solar thermal plants planned in California won’t use dry cooling. But Desmond says, even though the state needs renewable power, he doesn’t think agencies would approve that today. “I think it’s safe to say if somebody said we’d like to use water cooling, that getting a permit for that would be challenging to say the least.”

The same could be true for fossil fuel plants, too, as California’s future water supply is called into question more and more.

Explore the Water and Power series and hear Lauren’s radio story on KQED’s The California Report.

Forcing utilities to pay for their carbon emissions, as California plans to do, will mean more costly megawatts. Six months before formal compliance with the state’s new cap & trade system begins, regulators are still sorting out what to do about that.

One of them is to provide rebates to offset hikes in electric bills. A new report from the clean-economy advocates, Next 10 attempts to sort out the options and put some concrete numbers on them. For example, the authors estimate that for PG&E customers, pricing carbon will add somewhere from two-to-seven dollars a month to summer electric bills, and anywhere from $2.50-to-more than $10 for customers served by Southern California Edison. Where you fall in that range depends in part on which of California’s many climate zones you live in. Places like the Inland Empire, which rely more on air conditioning, would fall in the upper end of the range.

Next 10

Chart shows the potential impact of cap & trade on electric rates for customers of various California utilities.

Authors Dallas Burtraw and Sarah Jo Szambelan figure that there should be enough cash from cap & trade to completely offset increases to electric consumers from cap & trade, but not to offset increases from the state’s transition to renewable sources of energy.

We’re not talking about chump change here. Estimates of the state’s annual take from cap & trade range from somewhere between a half-billion and $1.6 billion in the early going, to nearly $6 billion once the program expands in 2015. It’s hard to pin down because no one really knows what the price of a metric ton of carbon will be. Around $30 is a number that keeps coming up in projections but no one will truly know until the market is up and running, late this year.

“Electricity costs are going to go up,” Burtraw says bluntly. The questions are: who bears the brunt of those increase? Exactly how to protect retail customers from electrical sticker shock is a topic of intense debate. So far, three main approaches have emerged in discussions:

• Use all the proceeds from utilities’ permit fees to offset electric bills
• Use 90% for rebates and invest the remainder in energy efficiency
• Split the money roughly 50/50 between investments in clean energy and efficiency

Presumably those “investments” would include offering homeowners deals on upgraded appliances, insulation, and so forth. Even the cash rebates themselves present a puzzle. Should your utility simply knock something off your bill, or send you a separate rebate check? It matters, says Burtraw, who argues that consumers should at least see the impact, if not feel it. Otherwise they might not be motivated to save energy. “If that cost increase is not passed along to ratepayers,” Burtraw told me by phone from New York, “then ratepayers, at their end, will not be making adjustments that reflect the real cost of electricity.”

Regulators are expected to decide on a plan in June.

BrightSource Energy

Solar-thermal plants use mirrors or "heliostats" to focus sunlight on a tower receptor that produces steam to generate electricity.

A major barrier for solar power has always been that it doesn’t work at night (Duh). A few years ago, developers of big “utility-scale” solar projects were able to shrug this off to some degree. But Oakland-based BrightSource Energy has reversed field and decided to add to several projects the ability to store electricity for distribution after dark.

BrightSource managers say times have changed. Where utilities once wanted all the renewable capacity they could get, to meet state requirements, the priority has since shifted to having those renewable electrons available when they’re needed.

“The challenges of integrating photovoltaics and wind into the grid have driven a much deeper appreciation for those that can be highly reliable,” BrightSource CEO John Woolard told me in a phone interview.

But another driver is — well — us. When I interviewed Woolard a couple of years ago, I asked him why his company wasn’t including storage technology in its California projects. He said it wasn’t needed in California, which had a different pattern of electrical use than, say, Arizona.

That’s changing. Woolard says peak demand, which has traditionally hit around 4 p.m., has been shifting to later in the day, and by the end of this decade, will probably happen around 6 p.m. He says changing lifestyles are behind the shift, such as when people arrive home and fire up their air conditioners and other appliances.

BrightSource says it will use a molten-salt technology to store the power, rather than huge banks of batteries or experimental technologies such as flywheels. “That’s a solution for 2050 or 2060,” Woolard told me, “depending on whether you’re an optimist or a pessimist.”

Here’s a good summary of how it works, from The Energy Blog:

“The molten salt, with properties like water at temperatures above its 240^oC (464^oF) melting point, is pumped from a large storage tank to the receiver, where it is heated in tubes to temperatures of 565^oC (1049^oF). The salt is then returned to a second large storage tank, where it remains until needed by the utility for power generation. At that time, the salt is pumped through a steam generator to produce the steam to power a conventional, high-efficiency steam turbine to produce electricity. The salt at 285^oC (545^oF) then returns to the first storage tank to be used in the cycle again.”

BrightSource will add molten-salt units to three of its projects in Riverside and San Bernardino Counties, but not to its Ivanpah Valley project, already under construction near the Nevada border. Spokesman Keely Wachs says that the added cost will be “fairly nominal,” and that expanding the plants’ operating hours will, in effect, reduce the price of energy from those plants.

CEO Woolard says that despite plunging prices for conventional photovoltaic solar panels, BrightSource will not be joining a trend among developers to convert some of their giant solar arrays to PV. He says PV output tends to peak at noon (PV power is a function of light, not heat), so their output is falling just as demand is rising. He says that by adding storage capacity to solar-thermal plants such as his,”You can extend when you deliver power and and you’re delivering more of it when the real system peak is.”

Craig Miller / KQED

A new study suggests that massive electrification will be required to meet California's 2050 goal for greenhouse has reductions.

Chances are you’ve at least heard about California’s legal requirement to wind back greenhouse gas emissions to 1990 levels by 2020. But the state has a longer-term goal to knock another 80% off that by 2050. Is that even possible?

A new study suggests that it is — but not without a wholesale transformation from an “oil economy” to an “electric economy.”

The study, a collaboration of economists and energy forecasters at several institutions, including Lawrence Berkeley National Lab, three fundamental resets will be required to make that goal:

• Continued advances in energy efficiency, at home and at work

• A grid powered with nearly carbon-free electricity

• Massive electrification of — well, most things, including transportation

The study suggests that biofuels (principally ethanol and algae-based biodiesel) could cover the gap where it’s impractical to electrify transport, such as long-haul trucking and airline fleets.

The authors ran the numbers to see how much each measure would have to contribute, concluding that more than half the headway could come from a combination of energy efficiency gains (28%) and replacing fossil fuel power plants with renewable energy (27%). California currently requires utilities to get a third of their power from renewable sources by 2020. Most appear to be on a path to meet that goal.

Other measures would include so-called “smart growth” planning strategies, greater use of rooftop solar panels and biofuels. But 16% of the solution would require the massive conversion to electrical power of things that typically run on other fuels today; motor vehicles, public transit, industrial processes and heating of buildings.

Sciencexpress / sciencexpress.org

Graph shows the roles that various measures could play in meeting California's 2050 target for greenhouse gas emissions.

The article, by James H. Williams and seven co-authors, appears at Sciencexpress.org, a publication of the AAAS. Downloading the full article requires a subscription.

Flickr/zoonabar

A UCS study says US power plants are sucking up three times the volume of water that goes over Niagara Falls on a daily basis.

For the second time in as many weeks, a major report has emerged warning of consequences from the demand that America’s electricity producers are placing on water supplies.

Today’s findings, from the Union of Concerned Scientists, conclude that water and power are on a collision course in the US, as nearly all major power plants slurp up water for cooling. As of 2008, the UCS study found that across the US, “thermocooled” power plants (which is most of them) took up somewhere between 60 billion and 170 billion gallons of water from rivers, lakes and aquifers. That’s three times the volume of water that pours over Niagara Falls. At least 2.8 billion and as much as 5.9 billion gallons of that was “consumed,” or not put back.

UCS

Power Plants are putting strain on watersheds throughout the nation, according to UCS researchers.

“It’s really water that keeps the lights on,” says Kristen Averyt, deputy director of the Western Water Assessment at the University of Colorado, and lead researcher for the report.

Coal, natural gas and nuclear plants — even some solar power plants — produce electricity by generating steam to power turbines (90% of the nation’s electricity is produced in this way), and require “vast volumes” of water for cooling. The authors say this, in turn, is putting stress on watersheds around the country.

UCS

Power plants vary widely in their "water intensity."

The good news is that California and Western plants tend to be less water-intensive than elsewhere in the nation, though the authors say that among Texas plants, nearly half the water used comes from underground aquifers. Here in California, many major power plants are located along the coast and use seawater. But all plants have one thing in common: they tend to put back the water much warmer than when they withdrew it.

“Fish can’t climb out of the hot tub,” says Rob Jackson, who studied the effects on water temperature from plant cooling for the UCS report. Jackson says that despite bans by several states on putting back water hotter than 90 degrees Fahrenheit, eleven of those states have power plants exceeding the limit. Jackson cited one plant in Florida, which was found to be returning water to the Manatee River at 115 degrees, literally Jacuzzi temperature.

The report also points to “significant gaps and errors” in industry figures that purportedly track water use by power plants.

The UCS authors singled out one California solar plant as a paragon of water-efficient design. The Ivanpah thermal-solar array, under construction by Oakland-based Brightsource Energy, will use a “dry-cooling” system. That seems prudent, as it’s located in the middle of the desert.

A gigawatt – or a thousand megawatts – is enough energy for about 600,000 homes. Only five nations — let alone states — including Germany and Japan, have reached that level. “Even in a bad economy, the solar industry has been growing exponentially by 40 percent per year,” says Michelle Kinman of Environment California.

The goal comes five years after California’s Million Solar Roofs Initiative began, which mandates three gigawatts of rooftop solar by 2016.

The report credits the rapidly falling prices of solar panels for the growth, as well as the California Solar Initiative, a $2 billion solar rebate program. In 2007, the program provided a rebate of up to $2.50 per watt. As demand has grown, the program is designed to reduce the incentive. Today, it’s between 25-65 cents per watt.

“The real goal of the program is to create a sustainable solar industry in California that will continue to thrive without continued ratepayer incentives,” Scott Murtishaw of the Public Utilities Commission. “And I think that we’re achieving that. The installed cost of solar has fallen by roughly a quarter since the program began.”

The report says California is on track to meet the three-gigawatt goal in 2016. Adam Browning of Vote Solar says the state’s net metering cap could get in the way. Solar customers sign up for net metering contracts with their utility, so they’re credited for the electricity they generate. Right now, California utilities are only required to sign contracts for up to 5% of their overall load.
“There are clouds on the horizon and we’re going to have to lift the cap again,” says Browning.

Still, he says it’s a good story. “We’ve hit that transformation point with solar. It’s like cell phones. They’re nowhere until they’re everywhere. Once they hit a sweet spot, you see an explosion and I think that’s what’s happening now.”

Craig Miller

Wind is one of the few energy sources that requires virtually no water.

The Gordian knot of interdependence between water & power (not the political kind — that’s another story) has been getting a lot of attention lately as the “water-energy nexus.” A new report from Oakland’s Pacific Institute warns that as population grows and a changing climate further wrings water out of the West, “These trends will intensify water resource conflicts throughout the region.”

Oh, goody. Just what the West needs; more water conflicts.

Matthew Heberger / Pacific Institute

The Intermountain West

Defined by topography and climate, rather than political boundaries, the report focused attention on a region that takes in all of Idaho, Nevada, Utah and Arizona, and portions of seven other states, including a narrow vertical slice of California.

The authors calculate that power plants throughout the region “withdrew” (note that this doesn’t mean “consumed”) more than 1.1 million gallons of water each day to keep running, or about twice the amount that the City of Los Angeles uses in a year.

They further reckon that:

“Under current trends, by 2035, water withdrawals and consumption for electricity generation in the region are projected to increase by 2% and 5%, respectively, over 2010 levels – but water availability is already affecting power plant operations and siting in the Intermountain West.”

The report also catalogs how water is slurped up by the use of fossil fuels in particular, in extraction, refining and transportation.

The authors suggest that the way out of this conundrum is to move aggressively toward less water-intensive renewable energy, while pushing for more advances in energy efficiency.

Tillson Burg / iStock.com

Energy production casts a long shadow over an already-thirsty West. Steam-generating power plants like this one use the most water.

It’s worth mentioning that with the exception of wind power, most renewable energy requires some water — even photovoltaic solar “farms” have to be watered, so to speak, if only to wash the dust off the panels.

It’s also worth mentioning that the problem goes beyond just the anticipation of scarce water for cooling “thermal” power plants, which includes coal, natural gas, nuclear, and so-called solar-thermal facilities. The authors also point to more subtle pressures on the energy-water nexus:

“Warmer temperatures reduce the efficiency of thermal power plants and of transmission and distribution lines. More power will need to be generated, and more water withdrawn and consumed, to offset these efficiency losses. Likewise, reductions in hydropower generation and increases in electricity demand associated with warmer temperatures will increase demand for additional power generation and as a result, likely increase water withdrawals and consumption.”

In its 66-page report, the Institute concludes that “these alternative strategies can permit increases in electricity production with a significant reduction in total water demands, reducing pressure on scarce and over-allocated water resources.”

The research, by Heather Cooley, Julian Fulton, and Peter Gleick, was funded by the William and Flora Hewlett Foundation.

A key component of new solar panel technology being tested at Stanford. (Photo: Nick Melosh)

In a kind of cruel paradox, heat has always been the enemy of solar panels.  At higher temperatures, photovoltaic cells become less efficient, which is problematic in an industry where efficiency is the name of the game. That heat also represents wasted energy.

Today, researchers at Stanford University announced that they may have helped solve that problem. Nick Melosh of Stanford’s Materials Science & Engineering department set out to make use of the wasted heat. He and his colleagues created a solar cell technology that uses both light and heat to generate electricity. It’s called “photon-enhanced thermionic emission” (or PETE for short). “This is the first time that a process has been reported that can use the heat and the photons together harmoniously,” says Melosh.

Traditionally, solar power falls into two camps; those that make solar power from sunlight, which is what photovoltaic (PV) panels do, and those that make solar power from heat, which is what concentrating solar power plants collect. Melosh is hoping that this technology would bridge the gap between the two.

The PETE process is designed to work at temperatures above 400 degrees F, much hotter than silicon solar panels can stand. For that reason, Melosh sees the panels being used in solar farms in the desert. “It’s probably not something that you would  put on your rooftop, but out in the desert, they would be perfect,” he said. Melosh hopes to see the efficiency eclipse 50%, which would be double that of most solar panels today.  The panels could also be added to existing solar thermal farms, since the high-temperature waste heat from the PETE process could be fed into system.

The technology is still confined to the lab, but Melosh hopes to see a prototype in three years. In the meantime, his lab will be testing different semiconductor materials that could boost the efficiency of the process.

(Photo: Craig Miller)

California’s commercial buildings suck up more than a third of all the electricity used in the state–and that’s too much.

That’s among the conclusions of a new report from the San Francisco-based think tank Next 10. The 12-page report points out that on average, such buildings could cut energy use by 30% just by upgrading insulation, and another 18-to-20% with more efficient lighting.

Though California leads the nation in its stingy use of electricity overall, the report notes that efficiency standards for new construction are “well below what is possible” and what standards are in place are not met by 40% of new buildings. Study co-author Tracey Grose says that’s partly because even if state-of-the-art equipment is installed, it isn’t always used as intended. There are no energy efficiency standards at all for existing buildings. In general, the study finds that energy use in most buildings could be cut by 80% with some basic upgrades.

The report, compiled by the consulting firm Collaborative Economics in Mountain View, and largely a compilation of existing work, also implies that there’s a built-in way to pay for some of these improvements. The authors cite studies showing that commercial tenants are willing to pay higher rents for “greener” space. The report also cites figures from the Building Owners & Managers Association, that some basic improvements in energy efficiency offer a three-to-one return on investment.

Power consumption varies widely within the commercial sector. Next 10 notes that restaurants are the biggest kilowatt hogs per square foot, followed by supermarkets and hospitals (when’s the last time you had to wear a sweater while grocery shopping because the frozen food section was chilling the whole store?).

According to the report, while raw consumption has continued to rise, efficiency in these buildings has leveled off in recent years. Overall, the nearly 6.8 million square feet of commercial space accounts for 37% of California’s electricity use, compared with 40% for commercial buildings nationwide. The latter accounts for more than a quarter of the nation’s carbon dioxide emissions, according to the report.

Next 10, which describes itself as an “independent, non-partisan organization” has been a vocal promoter of the economic benefits from greening the state’s economy.

A "SmartMeter" mounted on a Fresno home. (Photo: Sasha Khokha)

The California Public Utilities Commission says it will name a consultant sometime this week to start testing PG&E digital “SmartMeters,” which customers have blamed for spikes in their utility bills.

The announcement came after state Senator Dean Florez (D-Shafter) held a press conference in Bakersfield to question why the CPUC hadn’t taken action. Last October, the Commission agreed to quickly hire an independent contractor to test the meters.
Florez got involved in the flap last year after some of his Central Valley constituents saw their bills triple with the new meters, even if customers bought energy saving appliances, or in some cases, when no one was living at the home. “The biggest savings recognized so far has been to PG&E, who were able to lay off numerous meter readers,” said Florez in a press release.

PG&E has blamed the higher bills on rate increases and hot weather (not a new phenomenon in the Central Valley, where people coddle their air conditioners as if they were household pets).

The Bakersfield Californian reported last month that the backlash here in the Central Valley is catching the attention of industry analysts and utilities nationwide, who want to avoid a spreading backlash against the new technology.

One of the groups sounding a warning is the Division of Ratepayer Advocates, an independent consumer advocacy division of the CPUC. Last week, it advised the Commission to reject a Southern California Gas application to fund its own $1 billion smart meter program. DRA argued not that utility bills would spike with new digital meters, but that money could be better spent on energy efficiency measures and appliances. DRA says SoCalGas is overestimating how much customers will reduce their usage if they can see a digital display of how much energy they’re paying for.

Part of the concept behind smart meters is to help utilities with “demand response” strategies; providing timely feedback to customers, who can use their home computers to see exactly how and when they’re using power, customers might then alter their consumption patterns to avoid peak demand periods, and cut utility bills.

But some of that strategy has already backfired. The San Francisco Chronicle recently reported that a document PG&E filed with the CPUC says the advanced digital smart meters will let the company shut off power to more customers who fall behind on their bills, since they can do so without having to send a crew to a customer’s home. The meters may be smart but consumer advocates say it’s a dumb strategy that will make it easier for the utility giant to leave customers out in the cold.