^{Former volcano Mount Konocti overlooks Clear Lake. Photo courtesy Stephen Nakatami of Flickr under Creative Commons license; all other photos by Andrew Alden.}

The Bay Area has been very familiar with earthquakes for at least 20 million years. Volcanoes might seem more remote, but their traces can be seen in many places. Lava flows and ashfall beds are widespread in our rocks, marking the progress of an ancient volcanic center through the area. And while the nearest active volcanoes are beyond the Sierra Nevada, they're close enough to keep an eye on.

California has three major sources of volcanism and one minor one. The minor one is what we have in the Bay Area, but let me mention the others first.

The classic type of California volcanism arises from subduction. This diagram shows how it looks for northernmost California today, with an oceanic plate traveling beneath North America. Water and sediment on top of the downgoing plate acts like a flux, promoting melting in the overlying plate. That's how volcanoes are produced all around the Pacific "ring of fire," and all of California used to look that way.

_{Cross-section from US Geological Survey Professional Paper 1515}

Today the Cascade Range volcanoes are produced by this mechanism. California members of the Cascades include Mount Lassen, which last erupted in 1917, and Mount Shasta, which may have erupted in the 1700s. South of that, this system was interrupted when the San Andreas fault system formed and began extending northward (now the boundary between the two tectonic regimes is a triple junction at Cape Mendocino). An example of Cascade volcanic deposits crops out south of Ocean Beach near San Francisco, a prominent ash bed in the seacliffs of the Merced Formation. It's known as the Rockland ash and came from an ancestor of Lassen volcano, called Mount Tehama, about 600,000 years ago.

The second major kind of California volcanism is beyond the Sierra, in the Mammoth Lakes area and points south. The last "supervolcano" eruption from that area was about 700,000 years ago, and ash from it (the Bishop Tuff) fell here although I don't know where to point you to it. That volcanism is related to stretching of the crust in the Basin and Range province, which basically includes all of Nevada and surrounding counties.

The third type of volcanism is related to Yellowstone, of all places. The geysers and lava flows of Yellowstone are the current location of an eruptive center that began about 16 million years ago in Oregon and slowly burned its way eastward across Idaho, leaving enormous plains of solid lava behind. Northeastern California has a lot of it. One of the first eruptions in that series came from California, sending a glowing flood of basalt lava our way. It flowed more than 200 kilometers as far as Vacaville, where it's mapped as the Putnam Peak Basalt.

_{Boulders of basalt akin to that in Yellowstone and Idaho lie west of Winters.}

You can inspect this rock at leisure on Route 128 west of Winters, about 2 miles west of Pleasants Valley Road. It's the location given at the top of this post.

OK, on to our own local volcanism. As the San Andreas fault system cut northward through our region, it cut off the preexisting subducting plate like a letter opener slicing across an envelope. The plate continued to descend, leaving behind it a traveling "slab window" that briefly allowed the hot underlying rocks of the Earth's mantle to send up magma. In the Bay Area, slab-window volcanic rocks came in three pulses. The first pulse dates from 11 to 8.5 million years ago. Its lavas have been dismembered by motion along the San Andreas and related faults, and now it occurs east of Hollister (the Quien Sabe Volcanics), in the East Bay Hills (well exposed in Sibley Volcanic Regional Preserve), at Burdell Mountain in Marin County, and the Tolay Volcanics between Petaluma and Santa Rosa.

_{Mineral-filled bubbles in lava beds at Sibley Volcanic Regional Preserve}

The next pulse of slab-window volcanism produced the large Sonoma Volcanics between 8 and 2.5 million years ago. A good place to see these is at the Petrified Forest park west of Calistoga, where whole redwood trunks have been fossilized in the silica-rich ash.

Since then, slab-window volcanism has migrated north to the Clear Lake/Geysers region. Mount Konocti, overlooking the lake, is a recent volcanic construction. The famous hot springs get their heat from this volcanism. And the huge geothermal power complex at The Geysers, based on natural steam heated by underlying magma, supplies electricity to the Bay Area, helping you read this story.

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Here's some of the equipment you can us to create your own geothermal heat pump. And you'll need a shovel.

Henry Gifford is a man who designs mechanical systems for very energy efficient, comfortable, and affordable apartment buildings in New York City, along with his partner, architect Chris Benedict. In a recent article in Fine Homebuilding, Henry explained how geothermal heat pumps work in a way that I will always remember. I paraphrase:

Dig a hole in the ground. Put some buckets of water in the hole. If you are deep enough below ground, the temperature of the water in the buckets, after a while, will be about 55⁰F. Take the bucket into your house and put it in your refrigerator. The fridge will cool the water down to say 50⁰F, and the heat produced in the coils behind the refrigerator will add some heat to your house. Voila! You’ve created a geothermal heat pump.

Notice that the heat produced is not free. It takes electricity to run the refrigerator. And if you don’t want to spend your days hauling water in buckets from the hole in the ground to your refrigerator, you’ll want to install a water pump, which uses more electricity.

The very best residential geothermal heat pump system, according to Henry, has a coefficient of performance (COP) of about 3. This means that for every 2 watts of energy the system pulls from the ground, you have to provide only 1 watt of electricity. You get 3 watts out for 1 watt in. But a typical system has a COP of about 2.

Given that electricity is produced at power plants that use fossil fuels, and depending on the mix of fuels your utility uses to produce electricity, you will probably burn more fossil fuels using a geothermal heat pump with a COP of 2 than you would using an efficient gas- or oil-fired furnace. And geothermal heat pumps are much more expensive to install than traditional furnaces.

At Home Energy Magazine, where I work, we always tell people that if you have your house air sealed, insulated, and provided with the right amount of ventilation to keep you healthy, you can do just fine with a medium-efficiency furnace and burn much less fuel than you would with a high-end system—ike a high efficiency gas furnace—and a leaky house. For most of us, that’s the best choice of all, for heating and for cooling.

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And old, 19th Century windmill in contrast to wind turbines today.

Last summer I visited the Netherlands, the original home of the windmill. Surprisingly, I saw hardly any of the quaint structures we associate with Dutch wind power. One hundred years ago Holland had about 10,000 wooden windmills dotting its landscape. Today, barely 10% remain. What I saw instead were high tech wind turbines, white and spare and gracefully generating electricity with wind from the North Sea. Many view these modern day towers as an eyesore, but I see them as a sign of hope. Like giant flowers across a landscape, they symbolize for me a clean energy future. But wind power, and solar, have a handicap that fuels claims that renewables will never be more than a small percentage of U.S. power. These energy sources can't be counted on when night falls or the wind subsides. Their inconsistent and therefore unreliable nature poses a problem for a world with an enormous appetite for electricity. If only excess power could be stored on a grand scale, it might solve many of our energy problems.

It isn't that electrical energy isn't currently storable, but as Andrew Tang, Senior Director of PG&E’s Smart Meter program points out, the current generation of batteries can’t store electricity at a price that's cost effective. But both he and Steve Berberich from California System Operators were optimistic about future storage possibilities. Tang described an experimental project that uses a sodium sulfur battery the size of an 18-wheeler trailer. The battery would be located next to a substation, or somewhere in the network, and its stored power would be used during times of peak demand. He also talked about the future of plug-in electric cars whose batteries could both store energy and in theory put it back onto the grid when the car's not in use. Steve Berberich envisioned several possibilities for storing excess power. He proposed converting it to hydrogen, which could be burned in a gas plant or could be used in a fuel cell. And he suggested using power to compress air, which could be injected into the ground and called upon when the wind's not blowing and the sun’s not shining.

Whatever the final solution to storage, you can guarantee it will be a game changer in the renewable power industry. No longer will wind and solar be looked upon as unreliable. Hopefully this missing puzzle piece will go a long way towards helping us detach from our dependence on fossil fuels. But we’ll still be left with the challenge of getting all that clean, green energy onto the power grid. And you can be sure that environmental concerns, zoning, aesthetics, and cost will undoubtedly be cantankerous issues for years to come.

Watch the Climate Watch: Unlocking The Grid television story online.

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When I first began researching this story for QUEST, I was surprised that I hadn't heard more about geothermal power. It's never lumped into that renewable energy laundry list that's recited by politicians and journalists alike — you know, "…solar, wind, hydroelectric and biofuels". But it turns out that geothermal energy has really great potential.

To start, it's reliable. Geothermal is base load power, which means that the plants generate power at a constant rate around the clock. In fact, geothermal plants often have capacity factors of 86-95%, well above traditional base load generation such as coal.

It's clean. Geothermal power plants give off little or no sulfur compared to fossil fuel-fired power plants and they emit no nitrogen oxides. Emissions of CO2 per megawatt-hour are extremely low or absent for the newer flash plants. A typical geothermal plant may produce 1 lbs. of CO2 per MW hour. This figure compares with 1030 lbs. per MW hour of CO2 for a natural-gas fired plant, 1600 lbs. per hour of CO2 for an oil-fired plant, and 1820 lbs. per MW hour for a low grade coal-fired plant.

And, if the USGS assessment is accurate, and it probably is, geothermal power is abundant. According to the study:

"the power generation potential from identified geothermal systems range from 3,675 MWe (95% probability) to 16,457 MWe (5% probability); the power generation potential from undiscovered geothermal systems range from 7,917 MWe (95% probability) to 73,286 MWe (5% probability); and the power generation potential from Enhanced Geothermal Systems range from 345,100 MWe (95% probability) to 727,900 MWe (5% probability)."

So, what's wrong with it? As we touched on in the TV segment, there are several little drawbacks that no doubt should be considered. These include induced seismicity (little earthquakes that are triggered by geothermal developments), the initial expense of geothermal exploration and development, and the challenges of connecting the electricity generated by a geothermal plant to the grid at a point where there is sufficient available capacity to sell the electricity.

However, I was never really able to find a strong reason why geothermal energy should not be in everyone's renewables laundry list. And considering Obama included geothermal energy in his list during his last debate against John McCain, I would imagine we will all be hearing more and more about geothermal energy development in the months to come and beyond.

Watch the Geothermal Heats Up television story report online. And don't miss the steamy, behind-the-scenes photos for this story.

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Senior Radio Editor Andrea Kissack also contributed to this post.

When we started working on this project, we thought it would be easy to find people to interview: D.I.Y.ers with a passion for sustainable building who were testing out new technologies in their backyards. We called consultants, local suppliers, green-minded architects, and collected as many leads as we could. We found a handful of great subjects, but we never quite tapped into that centralized hub we'd envisioned. And that, it turned out, was the point. When you're a D.I.Y.er, you tend to D things Y.

Which is what's so appealing about these projects. Green innovators like those we meet in the radio piece and slideshow are working on their own initiative, spending much more time and money than they would with more conventional technologies, and running a high risk of failure. Ultimately, though, we'll all learn from their mistakes.

Wind Turbine

Chris Beaudoin fits one type of these backyard innovators: He's a long-time environmentalist willing to spend some extra cash trying out something new. San Francisco's Department of the Environment put Beaudoin in touch with Blue Green Pacific, a local company that will ultimately have two turbines up and running on Beaudoin's garage. So far there are only about five "micro-wind" projects like this in the city, about half of them operational. But stay tuned. Gavin Newsom is encouraging homeowners to experiment with wind turbines, and the state of California is already offering rebates on home turbines.

Dixon Beatty and Stephanie Parrot, who live in West Oakland, fall at the other end of the spectrum, what I'd call extreme do-it-yourselfers (though I'm sure they'll disagree). They've spent years remodeling a beautiful old Victorian in West Oakland that they still call a work-in-progress, despite well-functioning solar thermal and photovoltaic systems that keep the house warm and lit with almost no help from PG&E.

Dixon Beatty

When Lisa and Michael Rubenstein wanted to build their green dream home in Hillsborough they thought they would derive the majority of their energy from photovoltaic rooftop solar panels. PV Panels, afterall, have been the energy technology of choice for eco-friendly buildings. But as the Rubensteins waded further into construction, their architect suggested a geothermal heating cooling system. They were told geothermal can provide the most energy efficient, environmentally friendly home and so, they decided to go for it. Together, with PV solar and solar thermal panels, the Rubenstein's monthly energy bill is only eight dollars. Not bad for a 6,000 sq. foot home. It was an expensive project but what they have created is an experimental, contemporary home that gives living green a whole new aesthetic.
Lisa and Michael Rubenstein

Also merging modern design with eco-practical, is Sunset Magazine's idea house for 2007. PIX Located in San Francisco's Mission District, Casa Verde is Sunset's first idea house to be focused in an urban setting, The model home features solar and wind power, a green roof and a sleek, eco-friendly aesthetic.

Listen to the"Beyond Solar: Do It Yourself Home Energy radio report online, and watch our Web Extra: Generating Energy Right at Home slideshow.

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Quest Educational Resources

 Print Guide - Alum Rock Park

 Alum Rock Park - KML file

 Tips to get the kids in your life out into nature

 Designing an Exploration on Google Maps

Additional Links

• Alum Rock Park