In a world energy landscape dominated by coal, gas, oil, and nuclear, renewable energy sources such as wind and solar don’t stand a chance if we can’t find a way to store energy when the sun doesn’t shine and the wind doesn’t blow. In my last blog entry, I wrote about storing electric energy in a battery made of paper and nanotech ink (see The Paper Battery Chase). But it isn’t necessary to store electric energy. We can create hydrogen, using electricity generated from photovoltaic panels, and then use the hydrogen to fuel a fuel cell, which recreates the electricity. The Leaf Community in Italy is experimenting with this process. And energy changes forms in other ways. We can store heat from the sun and use it to create electricity in the dark. As in any energy storage and conversion process, if we can do it without losing too much energy in the process, we can add another tool to our renewable energy toolbox.
I add a little salt to the water when cooking spaghetti—it raises the boiling point so that you can cook the pasta more quickly, although I’m not sure it makes a big difference. Mostly I add salt to make the spaghetti taste better. The properties of a liquid salt—a mixture of sodium nitrate and potassium nitrate—are a little different. This liquid salt will store heat up to a temperature of 1,0000F, which is much higher than the boiling point of water, 2120F at sea level. The Pacific Gas and Electric Company, (PG&E) has contracted with SolarReserve LLC to store energy using liquid salt. The Rice Solar Energy Project will produce enough electricity to meet the demand of 60,000 households—about 150 megawatts—beginning in 2013.
The Rice Project uses a large circular field of mirrors to reflect light onto a central tower. Liquid salt is circulated through the tower and, once heated, it is stored in an insulated tank. When the sun goes down the liquid salt will still be able to heat water well past the boiling point to create steam, which can be fed into a conventional steam turbine to produce—Walla—electricity. The liquid salt, now cooled, is stored in another tank and is ready to begin the process all over again.
Quantum mechanics and Foosball? Credit: RickyDavid.
When I began this story, it seemed pretty simple. I'd heard that scientists at Lawrence Berkeley National Lab were working to mimic photosynthesis and create a man-made version of the process that could supply us with renewable energy.
The premise is to create a "closed-loop" energy system. Artificial leaves would use water, sunlight and carbon dioxide as inputs to create fuels like butane. Those fuels would be used for transportation or fuel cells. And by burning those fuels, we would produce carbon dioxide. The cycle goes on from there.
I never thought that quantum mechanics would enter the picture. That's what I discovered at the UC Berkeley lab of Graham Fleming. He says we have a lot to thank photosynthesis for. It produces the oxygen we breathe and is the basis for the entire food chain on the planet.
Fleming's lab is dedicated to understanding how photosynthesis works so well. And one of the things they've found is that plants are somehow tapping into quantum mechanics to improve their efficiency. It's pretty complicated – but with the help of the folks in Fleming's lab, they helped me understand it through, of all things, Foosball. Here's an audio version of it to help you out.
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To store power for the grid, we'll need some bigger batteries.
Credit: Heather Kennedy
"We believe energy storage is the next big thing," says Craig Horne, CEO of EnerVault, a Sunnyvale startup. His company is developing a battery that could help solve a renewable energy problem (check out our previous post): how to keep electricity flowing when we need it, even as more of it comes from sources we can't control. Horne was a panelist at a UC Berkeley-Stanford sponsored CleanTech Conference about energy storage held last week at Berkeley's Lawrence Hall of Science.
Proponents of energy storage think it has a key role to play in the future energy grid. A network of storage systems could act as a kind of shock-absorber, balancing the spikes and troughs of production that can come from solar and wind power. For example, if we had a way to store the power generated by wind turbines during a storm, we could release it later when demand gets high, making the power supply more constant.
We all use batteries daily – in cell phones or electronics – so it’s clear we already have the technology to store electricity and use it later. Unfortunately, that technology doesn't scale up very easily; batteries that can store enough energy to help smooth the grid are expensive, though company's like Horne's are hoping to change that. (For more on the challenges facing battery technology in particular, check out the QUEST TV story, Waiting for the Electric Car).
Batteries are just one strategy on the table, however; there are lots of ideas for how to store power at a large scale. One that's already in use in California is pumped-hydroelectric storage, which uses excess power to pump water from a low reservoir to a higher one. To get the energy back, you let the water flow the other direction, turning turbines to generate electricity as it drops in elevation. Compressed air energy storage (CAES), features a similarly clever use of the laws of physics, using excess power to compress air, which then releases energy as it expands later.
Another scheme includes using the sun – but in this case, it’s used to heat molten salt, which retains heat for a long time and can generate power even after the sun stops shining. Even electric cars could become a storage device if they become widespread, using their relatively small, distributed batteries to help feed power back to the grid at peak times.
So why aren't these technologies already being used all over the place?
"There are three obstacles to storage: Cost, cost, and cost," jokes Haresh Kamath, a Senior Project Manager at the Electric Power Research Institute, and also a panelist at the conference. Energy storage on the scale we'd need with the technology we have today is prohibitively expensive.
That may start to change, however. The stimulus package includes about $600 million for energy storage demonstrations, a 30% investment tax credit that applies to energy storage projects, and $2 billion for battery development and manufacturing. Venture capital firms are looking to invest. And there's a bill currently before the California legislature that encourages utilities to invest in and build storage.
Those injections of money and attention may be enough to get more energy storage projects off the ground – or at least get people thinking about them. Hopefully the conversations will keep going, and going, and going…
For more on the conference and specific storage technologies, check out this FAQ over at Earth2Tech.
When it comes to renewable power, California has had one main message: bring on the solar power, bring on the wind turbines! California and the country are heading fast towards a clean energy future. But renewables aren't perfect. As wind, solar, and other nature-dependent technologies start to make up a bigger and bigger part of our electricity mix, power providers are thinking about how to deal with a very real problem: you can't tell nature when to produce.
The issue with these variable, intermittent sources of power is that electricity is a "just in time" commodity: you use it as soon you make it. When you flip on the light switch in your house or push start on your electric dryer, a power plant somewhere is whirring away right at that moment, creating those electrons for you to use.
In most of California, that complicated balance is coordinated by the California Independent System Operator, or ISO, a nonprofit that serves as a link between power generators and the utility, such as PG&E. Every four seconds, the ISO "takes the pulse" of the grid to make sure that the supply of electrons flowing out of the power plants matches the demand for electricity. If there's a mismatch, the ISO can tell plants to cut back or ask other ones to turn on.
That's not an instantaneous process, though. What makes the ISO's job complicated is that power plants have different levels of responsiveness. Nuclear plants, for example, are slow to turn on or off, so they usually just hum away at a relatively constant rate, providing "baseload" power – the minimum amount of electricity we always need. Other plants, including hydroelectric and natural gas, can ramp up and down quickly throughout the course of a day, as factories switch on their machinery and air conditioners rev up.
Unfortunately, renewables such as wind and solar are even less accommodating. The wind blows when it blows – often at night, when demand for electricity is low. The sun is more predictable, but passing clouds can change a solar panel's output, and just because we know when the sun will be high doesn't give us any control over it. Put too much of this kind of energy on the grid, and the system stops being reliable (though researchers disagree about how much exactly is "too much").
According to California's policies, more solar and wind is what's in store. The state has an ambitious goal of getting 33% of its electricity from renewable sources by 2020. So how can power providers make sure the right amount of juice is flowing through the grid when more of those electrons come from sources you can't "dispatch" on-demand? One answer might be energy storage. Stayed tuned for an upcoming post on that.
I've never paid much attention to my electric meter. For most of us, it's just that box on the side of the house with a small white disk spinning inside, keeping track of our energy use. But over the next three years, all the meters of PG&E customers will be getting a major upgrade to a new, digital SmartMeter.
I met one customer, Ken Kube in Castro Valley, whose meter has already been upgraded. Since the new meters track his home energy use digitally, Kube can log into his PG&E account and see his real-time energy use. On one level, it's really the ultimate tool for parents who like to remind their kids to turn out the lights. But it's also a powerful conservation tool. Kube could see how much energy he uses at night, when his appliances are drawing power in stand-by more (what's known as "vampire" power).
These meters are just a small piece of the puzzle when it comes to a smart grid. Just what the smart grid is depends on whom you ask, but most people agree it comes down to one thing: communication. The energy landscape is changing rapidly. In addition to increasing demand, there's more renewable power like large-scale solar and wind coming online – which are often far from urban areas and are available intermittently. There's also small-scale solar on building rooftops – which means energy consumers are becoming energy producers. There will also be plug-in electric cars, which need to draw power from grid.
To manage all this, utilities and grid operators need more information than they have. And that's where meters come in. But as Kurt Yeager of the Galvin Electricity Initiative describes, it's a huge networking challenge – and a huge market opportunity.
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A number of companies have jumped into the smart grid market as a result, from Silicon Valley start ups to international corporations. As Eric Miller, the Chief Solutions Officer for Trilliant describes, managing the information flow in smart grid will be the biggest challenge.
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Other smart grid companies are banking on the consumer market. Google is developing the PowerMeter, an online tool that tracks home energy use. They're partnering with GE, who is positioned to work with utilities, with its meter technology, and with consumers, with smart appliances, as Sunil Sharan, the Director of the Smart Grid Initiative explains.
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1. The economic stimulus act provides $5 billion for the Weatherization Assistance Program; increases the eligible income level for the program from 150% of poverty level (determined by criteria established by the Office of Management and Budget) to 200% of poverty level; increases the amount of money that can be spent per home from $2,500 to $6,500; and allows weatherization assistance for homes that were weatherized before 1994 (previously, homes weatherized after 1979 could not be "re-weatherized").
2. $4 billion was allocated to the Department of Housing and Urban Development (HUD) to retrofit public housing, and $510 million to retrofit the homes of Native Americans.
3. The stimulus bill gives $500 million to the Department of Labor to train workers for careers in energy efficiency and renewable energy.
4. The American Recovery and Reinvestment Act of 2009 provides increased tax credits for homeowners for energy efficiency improvements and renewable energy installations; the act increases the tax credit for energy efficiency improvements from 10% to 30%, and gives a 30% tax credit for the cost of qualified solar energy systems, geothermal heat pumps, small wind turbines, and fuel cell systems.
5. The tax credit for homeowners who install a natural gas refueling system for a natural gas car, a charging system for a plug-in electric or hybrid vehicle, a hydrogen refueling station for a fuel cell car, or another refueling system in their homes is doubled from $1,000 to $2,000. The credit is good through 2010 for most refueling systems and through 2014 for hydrogen refueling systems.
There are many more provisions in the bill that support building energy efficiency, automotive energy efficiency, the manufacture and use of renewable energy systems, and research into (among other things) high performance batteries.
We recently covered in Home Energy Magazine a story from Italy about the Leaf Community. It is a live/work community outside of Rome where they create all the energy they need by taking it from the sun, the wind, and the ground (using geothermal heat pumps). They are doing a lot of research into storing energy, and that is clearly becoming a top priority among scientists. Energy produced from the sun and wind, for example, is intermittent, and sun and wind resources are often far from populations that need clean energy, requiring expensive transmission systems (more overhead wires). At Leaf House, they produce hydrogen using the electricity produced by photovoltaic solar panels, and store the hydrogen in a "chemical battery". The hydrogen can later be reclaimed and used in a fuel cell to create electricity.
Retrofitting homes to be more efficient, healthy, and sustainable is a "three-fer", as President Obama called it in a recent television interview: it saves energy; makes homes more affordable; and creates jobs. And research such as that taking place at Leaf House opens the door to unimagined, elegant solutions to our energy challenges. One thing that the economic stimulus package has already delivered — something that has long been lacking in the energy efficiency and renewable energy community — is hope.
Proposition 7 is one of the green propositions – in more ways than one.
The amount of cash that's being spent on this so-called Big Solar initiative is prodigious. It is one of the most expensive measures on the ballot. On one side you have a little more than $5 million to pass the proposition, all from Peter Sperling, the son of the man who created the online college, The University of Phoenix. And on the other side, three utility companies have pitched in well over $27 million to defeat it.
Interestingly, the companies that stand to profit from this initiative – the many small companies that make up most of the solar and wind energy industry – are actually against the bill.
PG&E and Southern California Edison are the two biggest donors, chipping in more than $13 million apiece. To see a list of spenders, for and against proposition 7, click here.
For more on the debate, check out this discussion from KQED's Forum.
Unless our sewage happens to end up in the Bay and in the headlines, most of us probably never give a second thought to where our wastewater is headed each time we run the tap or flush the toilet.
To learn more about the travels of sewage, I took a tour of the Las Gallinas Valley Sanitary District treatment plant led by Plant Manager Matt Pierce. The plant has been in operation for about 50 years and serves over 30,000 residents in north San Rafael.
After leaving sinks and showers throughout the District, wastewater travels through a network of pipes and pump stations. Once the sewage arrives at Las Gallinas, it passes through an inlet screen and a grit chamber, which together remove much of the dense, inorganic material-"like diamond rings," Matt jokes.
A lot of what happens at the plant is not that different from what happens in your compost pile: "It's basically bacteria at work," Matt points out. (The much bigger challenge for sanitation districts these days are all the unnatural things we're putting down the drain: household chemicals, personal care products, pharmaceuticals.)
From the grit chamber the sewage heads into a series of clarifiers, where gravity causes the organic solids to settle out. The biosolids pass through a thickener and then an anaerobic digester-the most, ahem, aromatic stop on our tour. After further thickening in storage ponds, the sludge is injected into a disposal field.
Meanwhile, the liquid from the clarifiers travels through two biofilters, where rotating arms spray the water over rock beds. The organic matter in the wastewater is a feast for microbial slime living on the rocks. In the nitrification tower, more microorganisms break down the ammonia in the water. In the final stages of treatment, the wastewater is chlorinated to kill any remaining bacteria, then dechlorinated since the chlorine is toxic to many aquatic species. Finally, the treated water is sprayed onto District fields or discharged into Miller Creek where it flows to San Pablo Bay.
The District has done a lot to minimize the environmental impacts of its operations. The plant is powered by a field of solar panels. The methane released in the sludge treatment process is captured and used to generate power and heat the digester. Some of the treated wastewater supports acres of fresh and saltwater wetlands-in fact the District's land is a favorite local gem for walkers and birders. And in a partnership with the Marin Municipal Water District, more than a million gallons of treated wastewater are recycled daily for landscape irrigation and other projects.
There are plans to make even fuller use of the reclaimed water. The Bay Institute-in partnership with the Sonoma County Water Agency, Las Gallinas, and three other North Bay sanitation agencies-has developed a plan to use recycled water for wetland and creek restoration and for agricultural irrigation. Legislation sponsored by Congressman Mike Thompson to establish the program passed the House late last year; Senator Dianne Feinstein has introduced similar legislation that we are hopeful will pass this year.
With California's growing demands for water, such creative means to conserve and recycle are critical to helping prevent this precious resource from just going "down the drain."
Ann Dickinson is Communications Manager for The Bay Institute (www.bay.org), a nonprofit research, education, and advocacy organization dedicated to protecting and restoring San Francisco Bay and its watershed, "from the Sierra to the sea."
In Silicon Valley, a battle between neighbors has turned into a different kind of face off: solar energy versus trees. It turns out that growing redwood trees can actually be a crime in California, if they block solar panels… as one couple in Sunnyvale found out the hard way. David Gorn reports on a new kind of legal battle — the struggle over who has the right… to sunlight.
7/23/08 UPDATE: The contentious battle between solar energy and redwood trees has come to an end. Governor Arnold Schwarzenegger has signed a bill into law that guarantees if California property owners plant a tree before a neighbor installs solar panels the neighbor can't require the tree to be chopped down, or trimmed, if it is shading their solar panels. Check out this article in the San Jose Mercury News.
It would be easy to think that the 2007 Energy Bill, signed by President Bush at the end of last year, was all about automotive fuel economy. The legislation that requires fleet-wide average fuel economy for cars and light trucks to reach 35 miles per gallon by 2020 has generated a lot of buzz. On the negative side, the lack of strong support for renewable fuels such as wind and solar has generated some buzz as well. I cannot find anything in the Bill about renewing solar and conservation tax credits for homes, and that is a big, big omission.But there is a lot in the bill that is positive for residential buildings–not enough to tackle problems like our addiction to fossil fuel and the specter of climate change, but certainly a step in the right direction.
Here are some home energy highlights, thanks to a summary of the bill by the Alliance to Save Energy, a nonprofit coalition of business, government, environmental, and consumer leaders:
Appliance energy efficiency: The bill establishes new external power supply efficiency standards, based on the standards of California and other states; updates and creates new appliance efficiency standards and test procedures and provides for a regular review of those procedures; updates boiler efficiency standards and creates an electricity use standard for furnace fans; creates regional, climate-specific standards for furnaces, air conditioners, and heat pumps; requires DOE to include consideration of energy consumed while in standby mode for appliances already addressed by efficiency standards in their active mode; and directs the Federal Trade Commission to require energy labels for televisions, personal computer monitors, cable and set top boxes, and digital video recorders.
Building efficiency: The 2007 Energy Bill directs DOE to set standards for manufactured housing that are at least as stringent as the International Energy Conservation Code (IECC) national model code. There are also lots of provisions to increase the energy and water efficiency of government buildings and to create green building demonstration projects. The latter’s effect on housing? The government’s purchasing power moves whole industries–in this case it moves the building industry in the right direction.
Lighting: The Energy Bill directs DOE to set performance standards for general-service light bulbs to achieve a 25%–30% savings compared to incandescent bulbs by 2012–14. The bill also directs DOE to establish Bright Tomorrow Lighting prizes for the development of solid-state lighting.
Green jobs: The Energy Bill authorizes a Department of Labor energy efficiency and renewable energy worker training program, and establishes within the Office of Solar Energy Technologies a grant program to create and strengthen solar-industry workforce training and internship programs for installation, operation, and maintenance of solar-energy devices.
The bill also supports the recommendations offered by a group from Lawrence Berkeley National Laboratory, including that of Home Energy Magazine Technical Editor Steve Greenberg, for greening the capitol complex, a set of buildings in Washington, D.C., including the Capitol, office buildings, and the capitol complex power plant. No mention is made of hot air energy recovery efforts from the chambers where Congress does its business.
Jim Gunshinan is Managing Editor of Home Energy Magazine. He holds an M.S. in Bioengineering from Pennsylvania State University, State College, Pennsylvania, and a Master of Divinity (MDiv) degree from University of Notre Dame.
The QUEST Community Science Blog explores local science, nature, and environment issues & experiences in Northern California. A collaborative effort, our many writers come from local museums, zoos, science centers and research institutions, as well as KQED's TV and Radio producers covering stories in the field.
The Rice Solar Energy Project will produce enough electricity to meet the demand of 60,000 households—about 150 megawatts—beginning in 2013. Click here for a full-size version of the diagram. Courtesy of SolarReserve.
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To store power for the grid, we'll need some bigger batteries.
The front of Leaf House. Photo credit: The Leaf Community
