Hydrogen is not exactly a fuel. That is, we don't burn it to make energy. It's used more as a medium for storing and transporting energy.

The science of hydrogen fuel cell systems is based on a simple concept. When you combine hydrogen with oxygen, energy is released. You get electricity. What makes it such a clean technology is that the byproducts of that chemical reaction are just heat and water.  So when a fuel cell takes hydrogen from a fuel tank and combines it with oxygen in the air, it produces electricity and emits only a wisp of heated water vapor from the tailpipe.

Hydrogen is combustible (remember the Hindenburg?), and needs to be handled carefully. However, there are easy ways to demonstrate electrolysis, which breaks water apart into oxygen and hydrogen, and the opposite process of joining those chemicals. In fact, you could make a type of fuel cell in your kitchen, with a popsicle stick, battery clips, Scotch tape and a few other household products. You do need one item that can't be found in your kitchen: platinum wire or platinum-coated nickel wire.

Hydrogen is the most abundant element in the universe. And hydrogen fuel cell conversion is a squeaky clean technology. But the production of hydrogen for use in fuel cells — that can produce a lot of carbon dioxide. In fact, most hydrogen is currently made by stripping, or re-forming, natural gas. That's one of the ongoing criticisms of fuel-cell technology, that it generates greenhouse gas emissions just to get the hydrogen in the first place.

Fuel cells also can store energy generated by solar-powered electrolysis, as well as similar energy generated by wind and hydropower. That's the kind of hydrogen generation that advocates hope to eventually use in fuel cells. But being able to store energy also makes it extremely attractive to harnessing wind, solar and hydropower.

For example, California could generate a lot of wind energy at night, but since electricity has to be used right away, that nighttime, offpeak energy is less valuable. But if it could be stored in a fuel cell through the electrolysis process, that would make it much more lucrative.

Listen to the Where's my Hydrogen Highway? radio report online, and watch our Web Extra Slideshow.

As this radio story airs, Congress is debating two Cash for Clunkers proposals, one from the Senate and one from the House of Representatives. (A third proposal, also from the Senate, is almost identical to the House version.) Both would pay consumers to scrap their "clunkers" in exchange for brand-new, more fuel-efficient models. Both define "clunker" as a car that gets less than 18 miles per gallon. But after that, they diverge.

The House version comes from Democrats on the House Committee on Energy and Commerce. If it passes, a consumer would get a $3,500 voucher for trading in a truck with 15 miles per gallon in exchange for buying a new truck that gets 16 miles per gallon - a one MPG difference. (If the new truck got 17 miles a gallon, the consumer would earn $4,500). That's why environmentalists complain that the legislation is more about stimulating car sales than it is about getting gas guzzlers off the road.

The Senate version proposed by U.S. Senators Dianne Feinstein (D-Calif.), Susan Collins (R-Maine), and Charles Schumer (D-N.Y.), puts the bar a bit higher. In order to qualify for the $3,500 voucher, that same replacement truck would have to get 20 MPG - five miles per gallon more than the old truck. (An improvement of seven miles per gallon would earn the consumer a $4,500 voucher.)

Interestingly, this is a compromise even for Senator Feinstein herself. Check out her original, more stringent, Cash for Clunkers bill here. Proposed in January, it required stricter efficiency from the replacement vehicle, and would have allowed consumers to use their vouchers for used cars, or for public transit. Those conditions were junked, presumably, because they don't stimulate new car sales.

This article from the Christian Science Monitor, takes the number crunching even farther. Among the details worth considering is the "carbon cost" of making all these new vehicles that consumers will be enouraged to buy, should C4C pass: between 3.5 to 12.4 tons of CO2 per vehicle, according to a Duke economist.

Listen to the Cash for Clunkers radio report online.

For these notes, I thought I'd focus on something that didn’t make it into the sea lions radio broadcast: the necropsy.

Each year the Marine Mammal Center treats somewhere between 600-1000 animals, including California sea lions, Pacific harbor seals, Northern elephant seals, and steller sea lions. About half of them are treated successfully at the center and released into the Pacific. The other half either die naturally or have to be euthanized.

Most of them end up at the center's hospital after passersby spot the animals on the beach and sense something’s wrong. (The Marine Mammal center responds to calls anywhere between Mendocino and San Louis Obispo Counties — some 600 miles of coastline.) Some problems are human-caused, like boat-propeller injuries or ingested fishing nets and hooks. Other times, it's cancer, domoic acid poisoning, or leptospirosis. Sometimes, it's hard to tell exactly what happened — hence the need for necropsies.

On the day that Quest intern Jennifer Skene and I visited the center, veterinarian Nicola Pussini performed two necropsies, both on sea lions. One animal seemed to have died from a tumor underneath his fin; the other was a suspected domoic acid intoxication.

Each necropsy takes about an hour and a half. First Pussini measures the animal, then he slices it open and inspects every part, from tongue to tail. He inspects the teeth, pulls out all the organs, checks to see how much fat the animal has. The data, along with tissue samples, are archived and shared with other research institutions. This is the kind of basic research that Marine Mammal Center staff cite when people ask why they devote so many resources (most of it from private donations) to animals whose populations are neither threatened nor endangered.

I should mention that I didn't exactly see this entire process firsthand. Let's just say that after my first strong whiff of sea lion intestine, I felt a compelling need to go check on things outside the necropsy room. Luckily for me, Jennifer has the stomach of a true scientist and managed to both hold the microphone and take photos. Luckily for you, we’re sparing you her gorier shots.

Listen to the Sea Lion Rescue radio report online, and watch our photo slideshow.

There is no proven cure for Sudden Oak Death. But that doesn't mean you can't find people selling cures.

In fact, the Internet is full of theories – and their related products – that explain how to treat Sudden Oak Death. The problem with them, says UC Berkeley researcher Matteo Garbelotto, is that they don't work. And in fact, he adds, they could actually harm people's backyard oak trees.

One of the most popular treatments says that part of the problem with oaks is that they're weakened by acidic soils (presumably from acid rain), and the theory is that heavy doses of calcium in the soil could restore natural balance and strengthen trees against the Sudden Oak Death pathogen. In hopes that the theory might bear fruit, the Garbelotto lab recently tested it.

The study found that it did nothing to stop the Sudden Oak Death pathogen. In fact, Garbelotto said, it's like giving a glass of orange juice to someone with a terminal disease. And in some cases, he added, it could have a detrimental effect.

A different Garbelotto study showed that a phosphonate fungicide, brand-named Agri-Fos, can prevent the onset of Sudden Oak Death, for a period of about two years. This is the only product on the market that is effective, he said – not as a cure, but as a two-year preventative.

Some people who love their oak trees decide to try both treatments, Garbelotto said. And since the phosphonate that does work is acidic, and the calcium treatment that doesn't work is basic, then you could end up inhibiting the treatment that actually works. That is, if you use both treatments, he said, the calcium could actually negate the positive effect of the phosphonate.

From 10 a.m. to noon on Sunday, May 16, Garbelotto will lead a "Sudden Oak Death Blitz" at the East Bay Parks Botanic Garden in Berkeley's Tilden Park. The event, sponsored by the California Oak Mortality Task Force, trains participants to spot vegetation infected with P. ramorum and collect samples for testing. The training is useful for homeowners who want to monitor their own trees for Sudden Oak Death.

Listen to the Sudden Oak Death radio report online.

The biggest problem can be the smallest thing, and that's the case in the sewer world.

More than 20 million gallons of raw sewage spilled into California waterways last year, according to the state Department of Water Resources Control Board. That's not counting the partially treated sewage that makes its way into our water from overflows and sewer system malfunctions.

Many big sewer pipes are old, and many of the sewage treatment plants are antiquated. But the biggest problem faced by sewer systems in California is the tiny pipe called the lateral.

That's the pipe that runs from your home to the street, the small pipes under all of our homes that end up joining the bigger sewer pipes. When those pipes develop cracks, water leaks into them.

Storm water itself would not overwhelm a sewage system, because it's designed to be a closed system. Storm water is not supposed to BE in sewer pipes. So in one way, it shouldn't even matter what the weather is like – storm water shouldn't really mix with sewage at all.

But during a rainstorm, water seeps into your broken lateral pipe, and all your neighbors' pipes, and that rainwater mixes with sewage in the sewer pipes, and the volume of water/sewage can actually build up far beyond the capacity of the sewer pipe. And in the same way, thousands and thousands of gallons of water mixed in with the sewage can swamp a treatment plant during a rainstorm.

That's the number one concern of sewage treatment plants now. And the sewer districts need your help.

Those laterals are owned by homeowners. They're on private land, so the district can't just go in there and tear them up to replace or fix them.

However, most sewer districts offer a service where they will inspect your laterals to check for leaks, and many have started programs where the district will help pay the cost of repairing or replacing those pipes.

Sewer systems are run by local municipalities. Most communities have a local sewer district, and officials at the district can help you inspect and fix your lateral pipes.

Listen to the Sewage Spills Increasing radio report online.

Cool the Earth is an organization that reaches into elementary school classrooms and Girl Scout troops all over the country, and they're working to make saving energy and being good stewards of our natural resources fun. Participating schools are given a packet of materials to kick off the program with an all school assembly, where characters like Koda the polar bear, Earth, Mother Nature, and Mr. Carbon (boo! hiss!) introduce the topic of global warming and how human actions contribute to the problem. The kids are inspired to save Koda's icy homeland by getting rid of the villain Mr. Carbon.

The students are given a small book of action coupons to take home that recommend tips such as powering down home electronics that use energy when officially "off" but are still in standby mode by unplugging the device or turning off the power at a power strip. Students can earn rewards in the form of prize cards featuring Wasteful Wendy, Rennie Reusable and other characters, for actions such as getting their families to eat one pound less of beef in a week, thereby saving 130,000 gallons of water (the water to grow the crops to feed the cattle, and so on.)

Monthly highlights focus on a particular action, and an Action Banner tracks the progress of the whole school, charting the amount of energy saved and the amount of greenhouse gases avoided. School teachers can go online to access materials, get advice from the staff of Cool the Earth, or just brag about how their school is doing.

The program is working because it employs an age-old motivational strategy– get to the parents through their kids. And the results are tangible. The program so far can account for more than 25 million pounds of carbon emissions avoided. There are 149 schools involved in the program so far, and there is a waiting list for participation. Almost 23,000 students are involved– translating into many more thousands of parents, brothers, and sisters.

Learning at the tidepools. Credit: Amy Gotliffe

This question comes up endlessly in the world of environmental education. How do you inspire a person to learn, care and then take action for the environment? As someone whose professional goal is to inspire earth stewardship, I often ask anyone who will answer this big question.

Many are active stewards because they formed a connection with nature during childhood. This bond is deep, instinctive and primal, and was merely coaxed out by a particular, yet often simple experience outdoors: playing in the woods, on the rocks, in the creek, in the garden, in the dirt, up the tree, with the roly polys, in the ditch, in the pond, in the vacant armory (ok that was me), etc. Somewhere deep inside, a door was opened to the potential to really care. This is why Nature Deficit Disorder is so disturbing, as we wonder if children growing up void of trees and ditches and ponds have forged the same bonds.

When a child's natural curiosity is nurtured by an adult, they will likely develop an even stronger connection. Some will have this head start, yet it is never too late.

So, how does a person then become an active steward?

One model is practiced by Roots & Shoots, the activism branch of the Jane Goodall Institute, and that is: Knowledge, Compassion and Action. All three experiences, in no particular order, can lead to a sustainable behavior change. Take caring for frogs as an example and consider three different people and paths to change:

• Sam is academically inquisitive about frogs and conservation, and is self-motivated to research the subject on the internet. He begs his parents to take him on a local frog conservation program and through this action develops a deep compassion for frogs.
• Stella read a non-fiction story about a particular pond that was suddenly quiet one season, after years of being a frog croaking Mecca. She feels compassion for this species and habitat and attends a lecture on the subject. Once in the know, she donates funds to a frog conservation project.
• Nik is neither interested nor compassionate about frogs, but finds himself on a service learning outing with his 9th grade class. There, he sees dead and floating frogs with his own eyes and collects frog eggs with his own hands. The experience inspires him to pay attention in class the next week and learn more about it, eventually leading him to feel greater connection and compassion.

With this model in mind, I suppose my job is to ensure that all three options are easily available to our visiting students and guests. So I encourage all you attend an adult lecture or ZooCamp program, take action with the Arroyo Viejo Creek Keepers, or feel compassion by staring through long eyelashes into the deep brown eyes of a camel… or frog.

By Rori Gallagher.

Even in these difficult economic times, California's population continues to grow, and those additional people are going to need a place to live. Recent legislation in California directs city planners to make environmentally responsible choices for new housing. One way to do that is to create transit villages.

The idea is to design housing near a transit station with easy access to retail and commercial space. That way people can drive less if they want to. Some transit villages are easy to identify as pre-planned developments, like the transit village in South San Francisco. Others developed more organically, like the area surrounding the Rockridge Station in Oakland.

As with all new development and redevelopment, there's always a concern about gentrification. Most cities have a requirement that a certain percentage of new units are offered below market rate. But some longtime residents of established communities, like San Mateo, worry about new development changing the character of the community. In order to make transit villages work, designers have to carefully blend new development with the existing community, creating a truly pedestrian-oriented destination. Check out a map of transit-oriented development in California. Also, here are some fun audio walking tours of transit-oriented development projects in the Bay Area.

Listen to the Mass Transit Housing Plan radio report online.

Dr. Lucy Spellman explains the plan for gorilla check-ups

Forgive me for being Gorilla-Crazy and writing yet another blog about these creatures, but anyone who has completed a gorilla trek understands the obsession and concern. One issue: We make them sick.

As gorillas share 97.7% of our genes, it is easy for pathogens to pass from us to them. These days, humans spend a lot of time in close proximity to the 740 remaining Mountain Gorillas. As the gorilla tourism industry continues to grow and thrive, researchers, trackers, tourists, guides, porters (and even poachers) crawl closer and closer. Though the industry promotes conservation and brings income to communities, it also brings illness to gorillas. The animals have little resistance to diseases we may carry (including scabies, polio, influenza, measles, and pneumonia), and when one gorilla picks up something, it can spread to an entire troupe, potentially leading to death.

The Mountain Gorilla Vet Project (MGVP) aims to alleviate these symptoms of the human invasion. The vets and researchers cover most of the home of the Mountain Gorillas — the Virunga Mountains, in Uganda, Rwanda and the Congo — with a headquarters in Ruhengeri, Rwanda. Our traveling group was fortunate enough to visit the headquarters and learn directly from Dr. Lucy Spellman. There is a lot to learn about the process of gorilla healing!

The first step is identifying the disease, which is no easy task. Staff must climb the mountain and find gorilla saliva samples. Back at the lab, they aim to not only ID the disease, but find out where it originated. It might be bacteria in the forest from humans, or mites from a farmer's fields. Once they've made a diagnosis, the vets are then allowed to carefully treat the gorillas in the park. But prevention is the best medicine.

Strict park rules on visitation help. Tourists may only stay an hour and must keep a distance from the gorillas. Tourists are also asked to be clean and healthy when trekking, a small price to pay for an encounter of a lifetime!

The other preventative tactic is to care for the physical well-being of all stakeholders. The MGVP practices the One Health approach, an innovative campaign with the goal of good health for everyone: gorillas, humans and the ecosystem. Community clinics and education help build the foundations of this campaign, and it seems to be working, one person, tree and gorilla at a time.

I still recommend a visit with this majestic forest royalty. Just take your vitamin C before you go!

The Truckee River Canyon. Credit: Michael Conner.

Natural capital isn't something we hear about very often, and it certainly isn't a new idea. Aldo Leopold and other conservationists recognized the role that natural ecosystems play in our lives as early as the 1940's. But understanding and measuring that role hasn't been easy. That's where the Natural Capital Project comes in.

The project focuses on ecosystem services - the natural processes that ecosystems provide and humans benefit from. Those include how forests filter our drinking water, how wetlands provide protection from storm surges, and how bees and other pollinators support our agricultural industry. While these services may not be the first thing you think of when it comes to nature, researchers are discovering that they're vital to human health and decision makers are starting to factor that it.

A few examples:

In the 1990's, New York City's water quality dropped below EPA standards. The obvious option was to built a new water filtration plant - with a hefty price tag: $6-8 billion for construction and $300 million in yearly operating expenses. Instead, the city decided to invest in the natural processes that help keep water clean. That meant looking upstream to the Catskills watershed where intact ecosystems could help filter the water. The city bought land upstream and improved sewer treatment plants - all at a much lower price: $1-1.5 billion.

In China, the Yangtze River Basin experienced devastating floods in 1998. Many believed the vast deforestation of the surrounding area had been the major cause, since it had eliminated the natural buffer that existed. Since then, the Chinese Government has adopted a system of ecosystem payments - giving subsidies to farmers to plant trees and preserve forested areas.  All in all, their program in budgeted in the billions.

The Natural Capital project has created an online tool known as InVEST that's freely available to the public. It allows users to map ecosystem services in any landscape. The project's co-found Gretchen Daily is hopeful that the tool will make it much easier for natural capital to be part of land use decision-making - especially in countries where development pressures are strong. "It's stunning to see how rapidly things are changing globally. We're losing trillions of dollars of value in natural capital in the form of rain forests and other key natural assets" Daily said. The project is already working with the government of Colombia to use InVEST and to improve their resource permitting process. You can read more about where else they're working here.

Listen to the Putting a Price on Nature radio report online.