welcome

"…..I find it troubling that this definition and virtually all references to sustainability since the Brundtland Report make no reference to LIFE. Instead of life, the subject under discussion is the human economy. The key word in the Brundtland definition is development – a word drawn from the literature of neo-classical economics where it generally take to be a synonym for growth – economic growth. ….. “… Perhaps some humility is in order, I believe that sustainability will not emerge in human affairs until we begin to conduct economic activity in harmony with the principles that shape all living systems on earth. Then we will view a business as a natural living system that thrives in a context of cooperation, restraint, and quality, not in a context of competition, growth and accumulation. That will be sustainability….. "

Sarah-Kate Templeton, Health Editor Novelist Jenny Colgan: Go on, guess how many children Jonathan Porritt has

COUPLES who have more than two children are being “irresponsible” by creating an unbearable burden on the environment, the government’s green adviser has warned.

Jonathon Porritt, who chairs the government’s Sustainable Development Commission, says curbing population growth through contraception and abortion must be at the heart of policies to fight global warming. He says political leaders and green campaigners should stop dodging the issue of environmental harm caused by an expanding population.

“I am unapologetic about asking people to connect up their own responsibility for their total environmental footprint and how they decide to procreate and how many children they think are appropriate,” Porritt said.

than two children is irresponsible. It is the ghost at the table. We have all these big issues that everybody is looking at and then you don’t really hear anyone say the “p” word.”

The Optimum Population Trust, a campaign group of which Porritt is a patron, says each baby born in Britain will, during his or her lifetime, burn carbon roughly equivalent to 2½ acres of old-growth oak woodland - an area the size of Trafalgar Square.

The British population, now 61m, will pass 70m by 2028, the Office for National Statistics says. The fertility rate for women born outside Britain is estimated to be 2.5, compared with 1.7 for those born here. The global population of 6.7 billion is expected to rise to 9.2 billion by 2050.

Porritt, who has two children, intends to persuade environmental pressure groups to make population a focus of campaigning.

“Many organisations think it is not part of their business. My mission with the Friends of the Earth and the Greenpeaces of this world is to say: ‘You are betraying the interests of your members by refusing to address population issues and you are doing it for the wrong reasons because you think it is too controversial,” he said.

Porritt, a former chairman of the Green party, says the government must improve family planning, even if it means shifting money from curing illness to increasing contraception and abortion.

He said: “We still have one of the highest rates of teenage pregnancies in Europe and we still have relatively high levels of pregnancies going to birth, often among women who are not convinced they want to become mothers.

Michael Odell and his daughter Rosa at their home in Bristol, UK. Rosa is filling one of the families recycling bins as her father looks on. Photograph: Stephen Shepherd

One day last October I found my five-year-old daughter, Rosa, leafing through my passport, which I'd left on the kitchen table in readiness for a work trip. She was studying it with a frown and I assumed she was upset by the boggle-eyed menace of the photo-booth portrait. But she was actually closely scrutinising several pages of blood-red immigration stamps marking multiple entries to the United States of America. The ensuing conversation went something like this:

"How many times have you been on a plane to America?"

"About 40."

"And how many trees have you planted?"

"No trees."

"I'm going to tell Miss White."

For the past year, my three children and I have been living in Redland, a leafy middle-class enclave of Bristol. A 2008 survey conducted by marketing company CACI found it to be the greenest place in the UK. This means that eight in 10 people in the area counted themselves as "enthusiastic greens", compared with the less apocalypse-averse people of Basildon, Essex, where four in 10 count themselves as "environmentally unconcerned".

I moved here from Brixton in south London. I was not ready for the culture shock of an ultra-green existence. Everything is recycled. Whistling men in a green truck take it away on Thursdays. Stuff that I would put on eBay is offered around Redland in a spirit of green neighbourliness. I am writing this article on an office chair sourced from the pavement outside. There was one of those giddy notes saying, "Please help yourself!" attached to it. I'm wearing socks from one of the charity shops on nearby Whiteladies Road, which are better stocked than the new £500m Cabot Circus shopping centre in the centre of town. OK, so the buses are rubbish, but guilt levels among local drivers mean you might be offered a lift. Twice before Christmas I got approached by eco kerb-crawlers: "I just feel less guilty carrying someone else in the car," one of them told me. And he seemed genuinely disappointed that I only lived 200 yards away.

Yes, this is a green world, and the ozone layer sits a little thicker over Redland.

And then, of course, there is school. Miss White is Rosa's year one teacher at St Peter & St Paul's RC Primary School. In the past year, I have noticed Rosa has begun to recycle and energy-save and spout eco policy with exquisite fervour and zealotry. In the past six months I have been confronted by Rosa, who's like a recalcitrant, chubby-cheeked mayoress of an eco-town, over the following issues: energy-saving light bulbs (I use them in hallways but not in rooms where I actually want light instead of that jaundiced low-energy syrup); paper recycling; turning off the tap when I brush my teeth; carrier bags. And plane journeys.

I have begun to feel there are larger forces at work. I suspect I am a pawn in a covert re-education programme. I fear "pester power" is being organised to leverage pro-environmental awareness in parents - we are being bullied by a generation of pint-sized "eco-worriers". A friend of mine who agonised about remaining anonymous for fear of upsetting her son's school told me how, as part of environmental awareness, all the children in her boy's class had their lunch boxes inspected for high food-miles products and non-recyclable packaging. I know a Brixton parent concerned about her son's school's walk-to-school initiative because it is dangerous. I know a father who was apoplectic when his daughter was asked by a teacher to account for the carbon footprint arising from two foreign holidays.

Miss White is lovely. She has done a great job with Rosa's numbers and with her spelling. But I have started to wonder whether she now has a hand in choosing what tomatoes I eat, how long I spend in the shower and whether I can go to work by plane.

"It's a difficult area," she tells me. "I probably have influenced the class on the subject of carrier bags, because we've looked at pictures of them in the sea. And I may have told them that for Mrs Colley's [the school secretary's] last birthday we bought her a donkey in Africa instead of a conventional present. But they're so young I would never push an idea or preach. They are aware of the issues and actually they are often ahead of me."

I know some of Rosa's eco ideas come from the BBC series Pippin, where a bearded collie dog enthusiastically recycles. Others come from the book Teach Your Granny to Text, published last year by We Are What We Do, a former London community action group and now a self-styled social change movement. Its previous book, Change the World for a Fiver, was a best-seller and the new book is written by children, listing 30 ways they can improve life and the environment including "Walk your dad" and "Test your teacher".

Rosa also has a copy of How to Turn Your Parents Green, by Bristol-based writer James Russell, which states: "Only you can make the Groans [grown-ups] behave, because only you can make their lives a misery if they don't." The book suggests a levy of fines for anti-environmental infringements: 20p for every degree the home thermostat is set over 20C, 10p for every high-energy light bulb used, and so forth. In a signature moment, which perhaps illustrates the topsy-turvy power dynamic of our family, I had to read the more difficult passages of this book to Rosa first, before she could then launch her ideological war and start fining me.

In many ways, her school is quite laid-back, but it has stepped up its commitment to the environment with an application for eco-school status. The Eco-Schools programme was established after the 1994 Rio Earth Summit and now 50% of UK schools subscribe to the programme, whereby pupils audit for energy and water waste, collect litter, or even, in one case, grow their own food and sell it at a local market. They can then apply for bronze, silver and green flag awards.

Rosa's last school, St Bonaventure's, gained the coveted green flag in 2007. When I went back to meet the eco co-ordinator, Morwenna Thomas, the eco-reps of Class 2T were impressively mobilised. They told me about the Golden Boot awarded weekly to each class with the most people who walk to school. They've also produced their own reusable shopping bag and are working to get local shops on the Gloucester Road to give up plastic bags altogether.

But what really struck me about the children was their presentation and debating skills and how confidently they carry the eco message home. Eleven-year-old Layla Hall said that she is firm about making her family cook one evening meal, rather than four separate ones, to save energy. Eight-year-old Rose Bailey has taken it upon herself to lobby her brother to switch off his Xbox, even though sometimes he doesn't listen and "throws her on to the sofa".

Morwenna Thomas says the school's green flag status has been achieved with huge parent support. Even so, there is a political line that cannot be crossed.

"There is a point where environmental thinking crosses over into the political and you have to navigate that carefully. I don't want children carrying guilt because their parents won't or cannot afford to buy fairtrade fruit. And I don't think they should feel guilty if their parents really cannot let them walk to school because it's too far. A subject like the third runway at Heathrow just isn't age appropriate. That might be a subject for secondary school. We focus on little things."

At St Bonaventure's there is an impressive array of recycling apparatus. There is also a Silver Shoe award for the class who try hard to walk to school but don't make the Golden Boot. And there are also lots of crucifixes. I remind myself that St Bonaventure's and St Peter & St Paul's are Catholic schools. I find myself wondering whether environmentalism is seen as a scientific or religious issue.

"Our position is that we look after the world because God created it and it would be rude and ungrateful to mess it up. It is our responsibility to help look after it," Morwenna says.

The idea of pester power usually has negative connotations. For example, the TV regulator Ofcom banned a great deal of junk-food advertising during children's viewing times in 2007, so that parents weren't nagged into buying bad food. But eco-pestering has been neatly re-branded as "reverse socialisation", whereby children educate their parents on what's happening in the world. And it seems to have official backing. David Miliband, the former environment secretary, has stated: "Children are the key to changing society's long-term attitudes to the environment", and the Eco-Schools programme is part-funded by Defra.

Andrew Sutter runs Eco-Schools in the UK. He says he recently received a frustrated email from a mother whose child had stopped her vacuuming. "This child said she did it too much and used up too much electricity. It can be shaming to parents when children assert themselves, but I don't think it is a bad thing. Children are more powerful in getting these ideas across than either politicians or the media. They see footage of the polar bears dying and their reaction is, 'That is wrong. What can I do?'"

Professor David Uzzell from Surrey University has 30 years' experience as an environmental psychologist. His objection to reverse socialisation is less ideological. He simply says that it doesn't work. His research paper Children as Catalysts of Environmental Change looked at children in the UK, Portugal, Denmark and France. "The key finding," he notes, "was that children do not work as shock troops for environmental change. Coming home and proselytising is not the answer. It only works in a specific type of household where the environment is deemed a suitable topic for discussion at the dinner table and where parents are willing to play pupil and allow the child to play teacher. Basically, well-informed, middle-class families."

Frank Furedi, professor of sociology at the University of Kent and author of the forthcoming book The End of Education, objects on more fundamental grounds: "Mobilising children to police their parents' behaviour used to be something you only found in totalitarian societies. I grew up in Eastern Bloc Hungary and I remember children being encouraged to tell teachers if their parents listened to rock'n'roll." Furedi argues that the curriculum is being used as a "policy outlet".

"It's as though the politicians are saying: 'The parents won't change fast enough, let's get the children'," he says.

Yet maybe it's a policy that's working. In 2008 the UK Social Investment Forum conducted a poll of 1,500 parents which showed that 24% of parents cited their children as a key green motivator. Only 2% took their cue from politicians.

When I was growing up in the 70s I don't remember any ideological ideas being served at school and taking them home. The Nine O'Clock News came on and my family sighed. World view was delivered top-down. I waited until my teens before I embraced generationally divisive issues such as nuclear disarmament, the Falklands War and anti-apartheid.

Today, children are being mobilised far earlier. Sometimes it occurs to me that we're nurturing the most knowing and idealistic generation of kids. For a start, all human knowledge, for better or worse, is available to them through the internet. They won't smoke. They are wary of alcohol. They will recycle. But are they really thinking, or just acting like super-virtuous eco-bots? And are we right to worry them with so much at an early age? Judith Shard, mother of Rachel and Joel, has her concerns: "I support and encourage my children when they come home from nursery or school with ideas about how to save the environment, but they should not be made to bear the burden created by their ancestors."

I have two other children. Tommy is eight and Caitlin is 11. Environmental concerns have had less suction with them. Tommy likes dinosaurs and football. He accepts it's too late to save the dinosaurs and concentrates on his game. Caitlin has dutifully planted a few bulbs at the school gardening club. She wrote a poem for her teacher, Mrs Brogan, on the environment, but as she reaches pre-teen age, I notice there are powerful competing consumer instincts. A proliferation of teen tech (iPod, mobile phone, laptop), constructed under unknown wage rates in China and the Far East, have made eco soap-boxing more difficult. Also, the temptation of cheap clothes from Primark separate the sheep from the Oxfam Namibian goats. This Christmas marked a turning point. Her friend Ellen gave her a pencil case made entirely from recycled juice cartons. Caitlin gave Ellen a slice of unadulterated aspirational teen Americana, a DVD of Camp Rock.

"I do care, but I can't think about the environment all the time," she says when I ask her about it. Actually, I find it easier to talk to her about eco behaviour now she is experiencing real dilemmas and making difficult choices.

Rosa's eco epiphany has chimed with a five-year-old's scarily reductive thinking. If I get on a plane, I am killing a penguin. I accept I have been on a lot of planes. I accept that my counter-argument, "I don't really enjoy take-off or the food", is wearing a bit thin. Maybe I will plant a couple of trees. But the other day I wore a coat around the house, rather than putting on the central heating. Then I mulched the previous day's tea bags into the brown recycling box and turned on my solar-powered radio to hear that a third runway at Heathrow had just been approved. I felt like I was a part of some ridiculously tokenistic game.

"I think you have every right to feel miffed," Andrew Simms, policy director for the New Economic Forum, reassures me. "I think the government is acting like an inconsistent parent. Gordon Brown is making grand gestures about the UK leading the way on climate change and encouraging children to recycle, yet on major policy issues such as Heathrow, he slips the leash and does something entirely different. It undermines people's resolve - and that's terrible."

So while Gordon green lights nuclear power plants and third runways, the battle for the planet is being fought over domestic minutiae in a neo-Orwellian nightmare in my own home. Rosa reckons a two-minute shower with the temperature dial set at "medium" is ecologically sound. I think certain treats are inviolate and I ignore her.

But I sense a presence through the shower door as I hum and scrub. Small Daughter is watching me.

Rachel Shard, 5

"When I grow up I want there to be some of the world left for us"

"My brother Joel has a puzzle book which shows bears and wolves in the jungle. I try and tell him that bears and wolves and other animals in the jungle might die if we don't look after them. There are lots of things which threaten them. Litter's one. Litter blocks up the jungles and the animals suffer. I know that water is needed, too. We do Water Aid at our school. And sometimes we all share a bath at home.

Cato Tallis-Lock, 12

"I think my parents listen to me about the environment"

"I came up with the idea "Walk Your Dad" for the book Teach Your Granny To Text with my friend Edward. Both our dads work at home sitting at computers. We felt they needed more exercise. At school there is someone to tell you to do PE or swimming, but working at home there is less opportunity to exercise. Encouraging our dads to walk was about health and about the environment. I'm protective of the environment. I check if the lights are on and if the TV is on standby. Small things around the house make a difference, like turning off the tap when you're brushing your teeth. The big stuff is harder, though. We do go on aeroplanes, but not for short journeys. We drove to Spain last summer. I think my parents listen to me about the environment. But they do stuff anyway. If there was a child whose parent wasn't listening to them about the threat of global warming I'd say, show them a website which shows CO2 emissions.

Sunneka Deocampo, 8, Brighton

"I like growing seeds. I am growing an avocado to eat"

"I was born in a jungle. I don't remember it, but my mum has told me. I was surrounded by coconuts and flowers. I like growing seeds and I think if we grew more food and ate it that might be good for the earth. I am growing an avocado to eat. It's about the size of a satsuma now, maybe a bit bigger. You put it near the sun. You water it. It takes ages just to grow one, though. I don't know where my school dinner comes from. We need a lot of food in the school and I could never make that much. Mr O'Shea is my teacher and we talk about the environment in class. I turn off taps that are running. I pick up litter. I know cars are not good.
I live near the sea and I know if oil gets in it that isn't good for the birds. My sister Taneesha is seven. We made our own recycling box and we put our paper in it. I hope it helps. Mr O'Shea says it helps. My mum says it will help.

Recycle: Graduate students Valerie Esposito (r.) and Samir Doshi (l.) pose near the recycling station in the Davis Student Center at the University of Vermont. It is the largest LEED-certified (Leadership in Energy and Environmental Design) student center in the US. Mary Knox Merrill - staff

In Springfield, Mo., college students are about to see quite vividly how much energy they consume. Piles of coal will be on display in proportion to what's needed each day to power their dorms, computers, and dining halls.

At Radford University in Virginia, students may stumble upon a mock fight between a windmill and a smokestack (costumes courtesy of the campus Green Team).

At the University of Vermont in Burlington, audience members will be encouraged to bike or walk to a one-woman show in which the fictional first lady calls for a boycott against sex until the nation starts a serious dialogue about climate change.

The creative tactics are designed to draw students into a series of events this coming week known as Focus the Nation: Global Warming Solutions for America. Organizers bill the culminating day, Jan. 31, as the largest teach-in in the nation's history, drawing parallels to the civil rights and antiwar movements of the 1960s and '70s. More than 1,500 institutions, most of them colleges and universities, will host classes, documentaries, performances, energy-saving competitions, and discussions with political leaders.

Eban Goodstein, the man behind the mission, speaks about it urgently: "What our kids have to do is truly heroic," he says. "If they're going to stabilize the climate for their children, they have to rewire the entire planet with clean-energy technology."

Mr. Goodstein is an economics professor at Lewis & Clark College in Portland, Ore., and an author on environmental issues. The pace needs to pick up in order to hold global warming to low levels before it is too late, he says. "We owe our young people some focused discussion about the critical importance of the choices that are going to get made over the next couple years."

The impact of Focus the Nation depends on whether it preaches to the choir or fulfills its potential to reach a broader audience and inspire long-term commitment. A key question is, "Will [the students] take the message to their parents and grandparents?... Will it move from the campus teach-ins to the backyard barbecues of early summer?" says Gordon Mitchell, a communication professor at the University of Pittsburgh who has studied rhetoric and social movements. "That will in large part determine if this is a wave, versus a ripple."

The Focus the Nation website (www.focusthenation.org) has offered templates for activities, but a decentralized network of faculty, students, and other volunteers has seized the opportunity to tailor events for local audiences. Professors in fields as diverse as astronomy, economics, and classics will use class time to link their subjects to climate change.

That's what appeals to Galen Brown, the 19-year-old student coordinator for events at the University of Colorado, Boulder. "It targets everybody," he says. "One of the biggest problems with the climate campaign over the past few years has been the negativity.... I think it's best to harp on the positive – how we can stop [global warming] and how businesses can be efficient and make money while being green."

For Paul Weihe, a biology professor at Central College in Pella, Iowa, the scope of the event is unprecedented in his 10 years there. "People understand that this is the issue of our time," he says. His campus is affiliated with the Reformed Church in America, and the keynote speaker there will be Cal DeWitt, a minister and scientist who founded the Evangelical Environmental Network. "We've got so many different people from different backgrounds [participating]. In the past, this would be something the science geeks were into," Mr. Weihe says.

Alexander Wait, who teaches biology at Missouri State University in Springfield, will be heading to some local hangouts to help "break through the apathy." He'll give a talk at local bars during the "Save the Ales" pub crawl. With breweries facing a hops shortage, he says, "if you care about beer, you should care about climate change."

On the edge of Lake Champlain, the University of Vermont is hosting a week of events, which organizers hope will be just the start of continued action. They expect crowds at the Sustainable Burlington Design Charrette, a structured brainstorming session on ways the city can improve everything from transportation to energy usage. Local officials will be on hand to hear ideas, which will be archived for use by the mayor's recently created environmental council.

"It seems like climate change can just be overwhelming, [but these activities] show that we can actually do things personally and collectively to fight it," says Valerie Esposito, a PhD student and organizer at UVM. In April, the winner of a student sustainable-design contest will receive $3,000 to implement his or her idea on campus.

Timing Focus the Nation during the presidential primaries was deliberate, to encourage voters to press candidates on global warming. The related "Green Democracy" forums are designed to be nonpartisan, featuring groups and speakers of all political stripes, including governors and members of the US Congress.

There's much that adults can do to set the stage now, by investing in the creation of green technologies, Goodstein says, but only today's young people "have the moral authority to speak for the future.... So it's really important to engage [them] directly in dialogue with political leaders."

Outreach to established political leaders is one way in which these events differs from the Vietnam era teach-ins, Professor Mitchell says. Those were offered as the "more palatable carrots" paired with the "sticks" of sit-ins. But such pressure "is missing from this [Focus the Nation] exercise," he says. "People are not saying, we have to divest the university from stocks in Exxon, [for example].... It's all about 'Let's contact our congressional representatives.' It's very reformist, and in that sense it's a very sharp contrast with the message of the teach-ins from the Vietnam War era, that the establishment is corrupt.' "

Goodstein sees a different parallel: people feeling empowered to make change. Between 1960 and 1964, the American mood shifted from accepting segregation – even if most thought it was morally wrong – to a determination to end it, he says. By the same token, "The ultimate purpose of Focus the Nation ... is to move America by 2009 to the point where we say, 'Of course we can stop global warming. Of course we must.' "

If Super Bowl ads are a window onto the national psyche, America’s mental attic is cluttered with moose behinds, brain-devouring aliens—and the smart grid.

General Electric continued the drive to bring into the mainstream what until recently was just a wonky electricity-policy fetish—overhauling the way the country’s electricity transmission system works. GE’s ad featured the scarecrow from “The Wizard of Oz” scampering over electricity pylons singing “If I only had a brain.”

Plenty of clean-tech investors, utilities, and legislators figure 2009 will be the year of the so-called smart grid, which would turn the old, one-way power grid into an Internet-like intelligent way to move electricity from power plants to homes and businesses. It’s certainly a year of firsts, after President Obama included a reference to the country’s power grid in the inaugural address for the first time ever.

The recently-passed House version of the economic stimulus package includes $4.5 billion to modernize the electricity grid; the Senate version apparently offers a similar amount. General Electric’s scarecrow ad—like its wind-power-themed ad that ran later in the game—is part of the congolmerate’s push to get in on the energy provisions of the stimulus package. GE recently teamed up with Google to find ways to make the nation’s power grid smarter, for example.

But as Earth2Tech notes, after years in the wildnerness, energy efficiency and smart grid technology is suddenly becoming a hot sector for investors, raising the question of whether GE will be able to fend off a slate of new, nimble smart-grid specialists.

In any event, even if smart grids popped into the nation’s consciousness Sunday night, they may not stay there. None of the advertising executives surveyed by the WSJ had anything to say about the GE ads, though one did offer advice for the next ad campaign: “A shot to the crotch is always a big winner.”

Last year, an anxious, depressed 17-year-old boy was admitted to the psychiatric unit at the Royal Children's Hospital in Melbourne. He was refusing to drink water. Worried about drought related to climate change, the young man was convinced that if he drank, millions of people would die. The Australian doctors wrote the case up as the first known instance of "climate change delusion."

Robert Salo, the psychiatrist who runs the inpatient unit where the boy was treated, has now seen several more patients with psychosis or anxiety disorders focused on climate change, as well as children who are having nightmares about global-warming-related natural disasters.

Such anxiety over current events is not a new phenomenon. Worries about contemporary threats, such as nuclear war or AIDS, have historically been woven into the mental illnesses of each generation. But global warming could have a broader and deeper effect on mental health, even if indirectly.

"Climate change could have a real impact on our psyches," says Paul Epstein, the associate director for the Center for Health and the Global Environment at Harvard Medical School.

Over this century, the average global temperature is expected to rise between 1 degrees and 6 degrees Celsius. Glaciers will melt, seas will rise, extremes in precipitation will occur, according to scientists' predictions.

There is evidence that extreme weather events, such as droughts, floods, cyclones, and hurricanes, can lead to emotional distress, which can trigger such things as depression or post-traumatic stress disorder, in which the body's fear and arousal system kicks into overdrive.

After Hurricane Katrina, rates of severe mental illness - including depression, PTSD, anxiety disorder, panic disorder, and a variety of phobias - doubled, from 6.1 percent to 11.3 percent, among those who lived in affected regions, a 2006 study by the Hurricane Katrina Community Advisory Group said.

Rates of mild-to-moderate mental illness also doubled, from 9.7 percent to 19.9 percent.

"After a disaster, people can feel inadequate, like outside forces are taking control of their lives," said Joshua Miller, a professor at the Smith College School for Social Work who responds to disasters worldwide. "They can't see a positive future. They tend to lose hope or become depressed."

Severe disasters also destroy the infrastructure needed to provide mental health care, and forcibly displace people, severing social connections when people need them most, Miller said.

Climate change is expected to create about 200 million environmental refugees by 2050, according to the Intergovernmental Panel on Climate Change, the international body established within the United Nations to evaluate causes and consequences of global warming.

Of course, no one can predict what effect warming will have on our psyches. The links between mental illness and the weather can be tenuous or even downright contradictory. Depending on which studies you read, suicide is more common, less common, or equally common in hot weather. Ditto dry weather.

But even in the face of uncertainty, specialists say the indirect effects of global warming could be substantial.

Though much of the anxiety centers on the possibility of extreme weather events, global warming will also transform the natural environment in a more gradual way, they say. These changes could have their own effect on mental health.

"It's not all trauma," said Carol North, a psychiatrist who runs the trauma and disaster program at the Dallas VA Medical Center. "Some of it's a quiet decline of quality of life."

Indeed, climate change may eventually deplete natural resources, make it more difficult for people to live off the land, and disrupt the global food supply.

"That will mean declining socioeconomic status and quality of life across the world," North said, and "depression, demoralization, disillusionment."

In India and Australia, where severe droughts have already taken a toll on agriculture, researchers have noted an uptick in suicides among farmers.

On the other side of the globe, the changing Arctic climate is expected to make hunting and fishing far more difficult for the people who live there. The Arctic Climate Impact Assessment says that such changes threaten Inuit culture, and that increases in domestic violence, drug and alcohol abuse, and suicide may result.

Glenn Albrecht, director of the Institute for Sustainability and Technology Policy at Australia's Murdoch University, has examined the psychological distress people experience in the face of this kind of slow, but chronic, change in their environments. His work with Australian communities living in areas changed by strip mining or drought revealed that people felt disconnected from nature, were no longer able to find solace in it, and they felt helpless.

"Climate change is a massive driver of change in people's home environment," Albrecht said. "These changes become sources of chronic stress."

Albrecht and his colleagues developed and verified an Environmental Distress Scale, designed to identify stresses related to the degradation of external environments.

"We tend to consider ourselves highly mobile global citizens, but we have a very profound connection to our environment," Albrecht says. "We tend to take that for granted."

So what's to be done? We need to train people to administer "psychological first aid," Smith's Miller said. That means making sure people feel safe after a natural disaster, and educating them about the kinds of psychological responses they might experience.

In the long term, we may also derive some psychological benefit from banding together with other citizens to mitigate the effects of global warming. Taking action might not only give us back a sense of our own sense of efficacy against a powerful outside force, but also help us build community and social ties that offset stress, said Epstein and other specialists.

"Getting involved can be an antidote to the depression that can come from the overwhelming realizations that we have to face . . . ," Epstein said. "It can be empowering to realize that what you do is effective."

Emily Anthes can be reached at emily@emilyanthes.com.

Britain face a shortfall in its electricity generating sector. Photograph: Christopher Thomond

Last week, the Guardian revealed that United Kingdom government officials are now negotiating to soften the impact of EU directives affecting the operation of fossil fuel-fired power stations and their emissions of sulphur dioxide (SO2) and nitrogen oxides (NOx). This is enormously embarrassing for the UK, but no surprise.

Indeed, it suggests that government, or at least the civil service is beginning to appreciate the full impact of the regulations for the future of the UK's electricity supply. Currently, the UK faces significant shortage in generation capacity by 2015 that is likely to lead to price rises for the consumer (a document leaked to the Guardian suggests price hikes of 20%) or power cuts at times of peak demand.

Indeed, industry analysts have been predicting for some time that the lack of reliable capacity in the UK electricity industry would force the government to seek humiliating exemptions from the EU Large Combustion Plant Directive and its successor legislation in order to keep dirty power stations online that would otherwise be phased out by the directive.

The government has underestimated the impact of the regulations and has failed to recognise that the LCPD would probably require the closure of the bulk of the UK's coal generation fleet by 2016. It has been unduly optimistic with regard to the construction of new combined cycle gas turbines (the only large power generation that will be built under the present policy regime in the required time frame, nuclear being unlikely to make any contribution until 2020).

It is also reckless in committing the UK to extreme dependence on imported gas (approx 80% by 2020) at a time of rapidly growing international competition for this fuel. In the wake of the Ukraine crisis this winter, this point is probably self-evident to all. Ministers have also failed to understand that the security of supply contribution from renewables, even if built, would be modest

The LCPD will close 13GW of existing coal and oil-fired generation because they do not comply with the SO2 regulations laid down in the directive. It is this pollutant which causes acid rain. Of those power stations that are sulphur compliant, some 20GW will probably fail to add equpiment to remove NOx because of high cost, physical difficulty, and the additional non-compliance of these plants with recently enacted climate change legislation.

30GW plus is a very large part of the UK's current generation portfolio – approximately 78GW – and is roughly half of the 60GW peak load on the network (5.30pm on a cold weekday winter afternoon).

Rectifying this situation requires significant global manufacturing resources and capital – some £100bn over the next decade.

After years of denial and misplaced optimism, awareness of the crisis has been growing in government. John Hutton while at the Department of Business, Enterprise and Regulatory Reform, seemed to understand this well. But the ministers at the newly created Department of Energy and Climate Change in their public statements seem to have no notion of the situation. Mike O'Brien, the Energy Minister, even said on 12 November that there was no problem, and that the lights "would burn even brighter" in 2015 than they do now.

Nevertheless, concern is growing in the industry and, it seems, the civil service. Hence the attempt by the government to quietly finesse the LCPD's successor legislation, the Integrated Pollution Prevention and Control directive. On the one hand, we appreciate the necessity of this action, but we deplore the air of fudging secrecy which surrounds it. Not only is this an undemocratic attempt to evade an admission of culpability, but it will deepen the anger of our EU partners who have complied with acid rain legislation. Better to honestly admit fault and seek exceptions from the new directive, laying out a clear plan for retiring our non-compliant plant as soon as possible and replacing it with new generation capacity that is fit for the 21st century.

A modern diversified power fleet must consist of nuclear plants, high-efficiency and therefore cleaner coal-fired power stations, including gasifiers predesigned to be ready to capture CO2 for the purpose of enhanced oil (and gas) recovery in the North Sea. Dedicated biomass and unlimited co-firing of biomass with coal might also help here, although most of this fuel will have to be imported. Offshore wind will also assist.

Furthermore, every means must be found to diversify our sources of gas supply, including the manufacture of synthetic methane from coal, with the resulting CO2 being captured. Additional gas storage, currently at a miserable 14 days' supply, is an imperative. Even assuming that this emergency plan is undertaken there is still the major risk of either a severe energy price shock or of interruptions of supply.

Even with these measures the UK faces a hydrocarbon trade deficit that will grow to over 150m tonnes of oil equivalent by 2015. Assuming a price of $100 per barrel of oil equivalent, the balance of trade will grow from $35bn in 2008 to $96bn per year in 2015. With no end to this growth in sight, it is reasonable to ask how the UK will generate wealth to pay for this vast, permanent, and growing imbalance.

John Constable is the director of policy and research of the Renewable Energy Foundation and Hugh Sharman is the founder of energy consultancy Incoteco.

Reps. Edward Markey (D-Mass.) and Todd Platts (R-Pa.) on Wednesday introduced legislation in the House to create a federal renewable electricity standard (RES) that would require the United States to draw a quarter of its electricity from clean sources by 2025. Markey also introduced a second bill that would require the country to reduce energy consumption 15 percent by 2020.

The American Renewable Energy Act [PDF] would put an RES in place starting in 2012. The legislators estimate that it would help create more than 350,000 new jobs over the next 10 years. Twenty-seven states and the District of Columbia already have RES's in place, including both Massachusetts and Pennsylvania, the legislators' home states.

Markey and Platts helped get an RES passed in the House last Congress as part of the 2007 energy bill, but the provision didn't make it through the Senate.

"With our economy in crisis, renewable energy can create hundreds of thousands of new green jobs, revitalize declining manufacturing sectors, and decrease global warming pollution," said Markey, who chairs the Select Committee for Energy Independence and Global Warming and the energy and environment subcommittee of the Energy and Commerce Committee.

"Establishing a federal renewable electricity standard will help to protect our environment as well as promote economic development and energy security," said Platts.

Markey's second bill, the Save American Energy Act [PDF], would create an energy-efficiency resource standard that mandates a 15 percent reduction in electricity demand by 2020. Markey estimates that the measure would reduce peak electricity demand by 90,000 megawatts and eliminate the need for 300 new medium-size power plants.

The Union of Concerned Scientists put out a statement in support of the RES bill, noting that it would increase power generation from renewable sources by 135 percent and provide enough clean electricity to power 150 million homes, according to its analysis.

"This electrifying standard would provide a smart, proven, cost-effective strategy to ramp up our clean energy use, create tens of thousands of jobs, and lower consumer utility bills," said Alan Nogee, director of the UCS Clean Energy Program. "The clean energy tax incentives that Congress is finalizing will get us moving in the right direction in the near term, and the renewable energy standard makes sure we stay on that path for the foreseeable future."

League of Conservation Voters President Gene Karpinski also praised the bill. "This bill will create an economic demand for wind, solar, and other renewable energy sources that will create hundreds of thousands of jobs in the coming years," he said. "It will help establish a powerful, productive, and profitable clean energy industry that will employ generations of Americans."

Jan. 7 (Bloomberg) -- In East Berlin’s communist-era apartments, warm air used to seep through drafty walls. Heaters had to run overtime, taxing power plants and increasing greenhouse-gas emissions blamed for global warming.

No more. A 2 billion-euro ($2.7 billion) urban-renovation program paid for foam insulation, cutting energy use almost in half, said Karin Lompscher, Berlin’s environment chief. The urban fund, also notable for turning human waste into biofuel, has helped the German capital trim emissions of climate-changing carbon dioxide 20 percent since 1990, according to city data.

From Berlin to Vancouver cities are creating bike paths, making windows air-tight and building cleaner power plants to counter the threat of global warming more quickly than national governments. When 189 countries sent delegates to Poland last month to debate climate change, proposals to reduce heat-trapping emissions worldwide were left on the negotiating table.

“As cities, we can no longer tolerate this inaction,” David Cadman, president of Local Governments for Sustainability and a Vancouver city council member, said in an interview.

In Berlin, where Max Planck won a Nobel Prize in 1918 for developing quantum theory of wave energy, sanitation engineers are using funds from the five-year-old urban-renovation program to set up a plant for burning methane from fermented human waste. Excrement will be used to create a combustible gas that releases less CO2 than coal, the traditional fuel for making electricity.

“We can’t belittle the opportunities to tackle climate change in cities,” Lompscher, 46, who studied architecture in Weimar, said in an interview from her office overlooking renovated apartments near the Alexanderplatz railway station.

Trams Versus Cars

Berlin’s building codes were changed to encourage residents to fix up homes and live closer together in the inner city. New trams and bicycle paths were added. Those measures led to a 2.6 percent reduction from 1998 to 2004 in trips by automobiles, one of the largest sources of CO2 emissions.

The city aims to keep car ownership low, Lompscher said. Berliners have 322 cars per 1,000 inhabitants, lower than the German average of about 500 per 1,000 population and the U.S. figure of 725, U.S. Department of Transportation figures show.

In Minneapolis, 100 miles (160 kilometers) of bike trails were installed in the past few years, bringing out cyclists even on snow-covered roads, according to the city’s Web site. The city is encouraging real estate developers to build more housing downtown to end the need for long commutes to suburbs, Minneapolis Mayor R.T. Rybak said.

‘Compact’ Cities Needed

“We need to reframe the city and make it more compact,” Rybak, the son of a pharmacist, said in an interview. Still, Rybak said he doubts the combined reductions of cities will make enough headway in slowing global warming. The big changes needed, from insulating buildings to installing emissions-free wind turbines for power generation, must come ultimately from national governments because they have much greater resources, he said.

In the meantime cities, not national governments, are taking the lead.

Toronto, Canada’s largest city with about 5 million inhabitants, double-paned windows and insulated many of its office towers built in the 1960s, Mayor David Miller said in an interview. The project will cut municipal emissions by 5 percent when completed, Miller said, without estimating the cost.

In contrast, a 5 percent cut pledged on a global level is faltering. Under the United Nation’s 1997 Kyoto Protocol agreement, 37 industrialized nations agreed to cut greenhouse gases an average 5 percent through 2012 from 1990 levels. More than half of the signatory nations are headed to miss their targets, UN data show.

New York Bicycling

Bicycle commuting in New York is increasing by an annual 35 percent, the city’s Department of Transportation said in an Oct. 30 statement. More bike paths and a spike in the price of regular gasoline to a record $4.11 a gallon in the U.S. in July helped.

Vancouver’s Cadman and Ronan Dantec, vice mayor of Nantes in western France, tried to convince delegates at the UN-sponsored talks last month in Poznan, Poland, to adopt CO2-emissions cuts of 30 percent by 2020. Cadman’s group of more than 1,000 cities worldwide seeks to reduce their greenhouse-gas output by at least as much as they asked nations to achieve, he said.

UN delegates at the final session of the Poland talks on Dec. 13 vowed to produce a new treaty to stem global warming, succeeding the Kyoto accord, by December 2009. That goal probably will be missed, said Alan Oxley, a former Australian diplomat.

“We can’t get a deal done within a year,” Oxley, who heads World Growth, an Australian non-governmental organization that promotes sustainable development, said in an interview.

Matching Kyoto

C40, a group of the world’s largest cities including Toronto and New York with a combined 700 million population, has committed to reaching Kyoto’s 5 percent reduction goals by 2012 from 1990 levels, Toronto’s Miller said. Measures will include insulating buildings and expanding public transit.

Cities are home to more than half the world’s population, a proportion that’s widening as people stream in from the country.

People flock to “see the lights and drink clean water,” Entebbe, Uganda, Mayor Stephen Kabuye said at the UN talks in Poland. An influx from Uganda’s countryside has overtaxed city water and energy resources; dead dogs and garbage are dumped into Lake Victoria. Kabuye said problems like these are best tackled by towns, where “the government is closer to the people.”

Back in Berlin, Lompscher said there’s more work to be done slashing emissions. Many buildings and power plants still need upgrading after the decades-long separation of eastern and western districts during communism. Also, more people might be enticed to ride bikes or buses that release less CO2 than cars.

“There’s a lot that comes down to lifestyle choices and those can’t be made by city or federal governments.”

To contact the reporter on this story: Jeremy van Loon in Berlin at jvanloon@bloomberg.net.

A new generation of lighting devices based on light-emitting diodes, LEDs, will supplant the common light bulb in coming years, according to a paper published this week by two professors at Rensselaer Polytechnic Institute.

Innovations in photonics and solid state lighting will lead to trillions of dollars in cost savings, along with a massive reduction in the amount of energy required to light homes and businesses around the globe, write co-authors E. Fred Schubert and Jong Kyu Kim.

If all of the world's light bulbs were replaced with energy-efficient LEDs for a period of 10 years, the researchers say it would reduce global crude oil consumption by 962 million barrels and reduce carbon dioxide emissions by 10.68 gigatons.

The researchers predict financial savings of $1.83 trillion over the 10 year period, and the number of required global power plants would be reduced by 280.

In addition to the environmental and cost benefits of LEDs, the technology is expected to enable a wide range of advances in areas as diverse as healthcare, transportation systems, digital displays, and computer networking.

Light emitting diodes (Photo by Schubert and Kim courtesy RPI)

"What the transistor meant to the development of electronics, the LED means to the field of photonics. This core device has the potential to revolutionize how we use light," write Schubert and Kim.

Schubert is the Wellfleet Senior Constellation Professor of Future Chips at Rensselaer, and heads the university's National Science Foundation-funded Smart Lighting Center.

Kim is a research assistant professor of electrical, computer, and systems engineering.

Their paper, titled "Transcending the replacement paradigm of solid-state lighting," will be published in the December 22 issue of "Optics Express."

Researchers are able to control every aspect of light generated by LEDs, allowing the light sources to be tweaked and optimized for nearly any situation, Schubert and Kim said.

In general, LEDs will require 20 times less power than today's conventional light bulbs, and five times less power than compact fluorescent bulbs.

With all of the promise and potential of LEDs, Schubert and Kim said it is important not to pigeonhole or dismiss smart lighting technology as a mere replacement for conventional light bulbs.

The paper stresses that advances in photonics will position solid state lighting as a catalyst for unexpected, currently unimaginable technological advances.

"Deployed on a large scale, LEDs have the potential to tremendously reduce pollution, save energy, save financial resources, and add new and unprecedented functionalities to photonic devices," the researchers write. "These factors make photonics what could be termed a benevolent tsunami, an irresistible wave, a solution to many global challenges currently faced by humanity and will be facing even more in the years to come."

"Transcending the replacement paradigm will open up a new chapter in photonics - smart lighting sources that are controllable, tunable, intelligent, and communicative," they write.

Possible smart lighting applications include rapid biological cell identification, interactive roadways, boosting plant growth, and better supporting human circadian rhythms to reduce an individual's dependency on sleep-inducing drugs or reduce the risk of certain types of cancer.

In October, Rensselaer announced its new Smart Lighting Research Center, in partnership with Boston University and the University of New Mexico, and funded by an $18.5 million, five-year award from the National Science Foundation's Generation Three Engineering Research Center Program.

The three primary research thrusts of the center are developing novel materials, device technology, and systems applications to further the understanding and proliferation of smart lighting technologies.

"Sustainability and energy efficiency are two key challenges of our time, yet they also present rich opportunities," said Rensselaer President Shirley Ann Jackson. "With innovation, ingenuity, and a clear vision, the NSF-funded Smart Lighting Center at Rensselaer will rewrite the rules for manipulating light and help introduce these new green technologies to the world."

Copyright Environment News Service (ENS) 2008. All rights reserved.

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Energy harvesting is the process by which ambient energy is captured, converted into electricity and used to drive small autonomous electronic and electrical devices. Globally, about 500 organisations are developing or applying energy harvesting other than photovoltaics.

As more energy-harvesting products hit the market, we can move forward from the technical issues to look at more commercial considerations such as payback.

Choices

Electrodynamics, piezoelectrics, photovoltaics and thermoelectrics are popular forms of energy harvesting. From the huge temperature differences in engines and exhausts, for example, thermoelectrics can produce watts per cubic centimetre, while piezoelectrics in actuators and vibration harvesters can exhibit 60% efficiency. Electrodynamics and photovoltaics exhibit a good compromise of both parameters.

Huge environmental and cost benefits

As much as 38% of energy is consumed in buildings, so long life and more affordable building controls are the focus of most of the 70+ companies in the EnOcean energy harvesting alliance which provides interoperable wireless sensors and controls that never need a battery. For example, EnOcean installed 4200 wireless and battery-less light switches, occupancy sensors and daylight sensors in a new building in Madrid, Spain. These are powered by energy harvesters and embedded in the building. This installation saved 32 km in cables, 42,000 batteries (projected over 25 years) and most of the cost of retrofitting, while saving 40% of lighting energy costs by automatically controlling the lighting in the building.

In similar applications, the value proposition for the Lightning Switch wireless switch technology from PulseSwitch Systems in the US emphasises the saving in construction costs. In one case, a 6600 m² industrial facility needed 21 banks of lighting with associated control. The contractor originally bid US$63,000 based mostly on the labour and overhead costs of installing more than 1600 m of conduit and switch wire. He then bid again and won, using various Lightning products to complete the job for US$10,000 for materials and 10 hours of labour.

This technology has applications in remodelling and renovation projects, since Lightning Switches — unlike re-wired switches — require no new wires, no demolition, no patching and no re-painting. Dividing walls supporting switches can be moved without rewiring. Another contractor wrote, “We tried your [PulseSwitch] product and saved the customer time, hundreds of dollars and the hassle of breaking into the drywall [plaster] and repairing the wall.”

Long life span

The long life expectancy of these alternatives is now a strong selling point for energy harvesting. Some electrodynamic vibration harvesters have an expected system life of 20 years, while the Lightning Switch piezoelectric light switches mentioned above have no battery and are reported to have a 20-year life span. Suppliers of the EnOcean piezoelectric light switches and allied controllers using various forms of energy harvesting claim a 25-year life, with over 500,000 installed already. A pattern therefore emerges by which the life of energy-harvesting devices without batteries is at least 10 years longer than the life of battery-driven wireless devices and this alone gives valuable paybacks.

Industrial and consumer applications lead the way

In the past, aerospace and military energy harvesting have attracted huge investment, but consumer applications of energy harvesting are rapidly increasing. They will remain dominant with industrial applications coming in to rival them. IDTechEx forecasts huge numbers of energy-harvesting devices to be sold into electronic medical disposables, e-labels, e-packaging and e-posters. Whereas today most calculators have energy harvesting, in future most torches, lanterns, wristwatches, mobile phones and other electronic items sold in billions may have it too.

Key enablers of the next generation

The next generation of energy-harvesting devices will be smaller, lower in cost and have lives exceeding 20 years in many cases. The energy density will improve but there is probably more scope for the efficiency to improve and that will also expand the addressable market. Many devices will be announced that work within the human body without need of further intrusive surgery. Many others will be embedded in apparel. Energy harvesting will power many of the billions of medical disposables needed for self-diagnostics and drug delivery as the demographic timebomb — too many old people — hits.

*Dr Peter Harrop, IDTechEx.

Japan has found a way to harness clean energy from thousands of stamping feet that pass through one of its busiest train stations.

Panels that generate energy from vibrations have been laid by ticket gates through which up to 80,000 passengers pass every day at Tokyo Station.

In theory, the piezoelectric system - consisting of slates, rubber sheets and ceramics - can generate enough energy to power automatic ticket gates or electric billboards at the station.

'This experiment is one of our ideas to help the environment,' said a spokesman for the joint venture between Japan East Railway and a government-backed group that has begun testing the system.

It is expected that the floors will produce 1,400kW/sec each day.

Tokyo Station is one of the country's most used and is the terminus for many of Japan's famed Shinkansen, or bullet trains.

Japan has tried to project itself as a leader in the fight against global warming, but like many other countries it is far behind in meeting its obligations under the Kyoto Protocol.

Energy harvesting (also known as Power harvesting or energy scavenging) is the process by which energy is captured and stored. Frequently this term is applied when speaking about small autonomous devices, like those used in sensor networks. A variety of different sources exist for harvesting energy, such as solar power, thermal energy, wind energy, salinity gradients and kinetic energy.

Traditionally electrical power has been generated from fossil fuels in large, centralized plants. Large-scale ambient energy, such as sun, wind and tides, is widely available but trickier to harvest. In urban areas, there is a surprising amount of electromagnetic energy in the environment as a result of radio and television broadcasting.

Harvesting

Energy harvesting devices converting ambient energy into electrical energy have attracted much interest in both the military and commercial sectors. Some systems convert random motion, such as that of ocean waves, into electricity to be used by oceanographic monitoring sensors for autonomous operation. Future applications may include high power output devices (or arrays of such devices) deployed at remote locations to serve as reliable power stations for large systems. All of these devices must be sufficiently robust to endure long-term exposure to hostile environments and have a broad range of dynamic sensitivity to exploit the entire spectrum of wave motions.

Energy can also be harvested to power small autonomous sensors such as those developed using MEMS technology. These systems are often very small and require little power, but their applications are limited by the reliance on battery power. Scavenging energy from ambient vibrations, wind, heat or light could enable smart sensors to be functional indefinitely. Several academic groups have been involved in the analysis and development of vibration-powered energy harvesting technology, including the Control and Power Group and Optical and Semiconductor Devices Group at Imperial College London, MIT, UC Berkeley, Southampton University and National University of Singapore.

Typical power densities available from energy harvesting devices are highly dependent upon the specific application and design of the harvesting generator. For motion powered devices, typical values are a few µW/cc for human body powered applications and hundreds of µW/cc for generators powered from machinery ^[1]

Motivation

The history of energy harvesting dates back to the windmill and the waterwheel. People have searched for ways to store the energy from heat and vibrations for many decades. One driving force behind the search for new energy harvesting devices is the desire to power sensor networks and mobile devices without batteries. Energy harvesting is also motivated by a desire to address the issue of climate change and global warming.

Devices

There are many small-scale energy sources that generally cannot be scaled up to industrial size:

• Piezoelectric crystals or fibers generate a small voltage whenever they are mechanically deformed. Vibration from engines can stimulate piezoelectric materials, as can the heel of shoe
• Some wristwatches are already powered by kinetic energy, in this case movement of the arm. The arm movement causes the magnet in the electromagnetic generator to move. The motion provides a rate of change of flux, which results in some induced emf on the coils. The concept is simply related to Faraday's Law.
• Thermoelectric generators produce energy from the heat difference between two objects. This is also used to power a type of wristwatch, as heat energy from the human body is radiated through the watch into the environment. Other than powering wristwatch, thermoelectric generators are also promising in the low power applications like wireless body area network (WBAN). Human, as an heat energy source, provides the electrical power to sustain the operation of the sensing and communicating devices. The operation is expected to last until the hardware fails.
• Micro wind turbine are used to harvest wind energy readily available in the environment in the form of kinetic energy to power the low power electronic devices such as wireless sensor nodes. When air flows across the blades of the turbine, a net pressure difference is developed between the wind speeds above and below the blades. This will result in a lift force generated which in turn rotate the blades. This is known as the aerodynamic effect.
• Special antennae can collect energy from stray radio waves or theoretically even light (EM radiation).

Ambient-radiation sources

A possible source of energy comes from ubiquitous radio transmitters. Unfortunately, either a large collection area or close proximity to the radiating source is needed to get useful power levels from this source.

One idea is to deliberately broadcast RF energy to power remote devices: This is now commonplace in passive Radio Frequency Identification (RFID) systems, but the Safety and US Federal Communications Commission (and equivalent bodies worldwide) limit the maximum power that can be transmitted this way.

Piezoelectric energy harvesting

The piezoelectric effect converts mechanical strain into electrical current or voltage. This strain can come from many different sources. Human motion, low-frequency seismic vibrations, and acoustic noise are everyday examples. Except in rare instances the piezoelectric effect operates in AC requiring time-varying inputs at mechanical resonance to be efficient.

Most piezoelectric electricity sources produce power on the order of milliwatts, too small for system application, but enough for hand-held devices such as some commercially-available self-winding wristwatches. One proposal is that they are used for micro-scale devices, such as in a device harvesting micro-hydraulic energy. In this device, the flow of pressurized hydraulic fluid drives a reciprocating piston supported by three piezoelectric elements which convert the pressure fluctuations into an alternating current.

Piezoelectric systems can convert motion from the human body into electrical power. DARPA has funded efforts to harness energy from leg and arm motion, shoe impacts, and blood pressure for low level power to implantable or wearable sensors. Careful design is needed to minimise user discomfort. These energy harvesting sources by association have an impact on the body. An international Workshop is organized by Virginia Tech on Piezoelectric Energy Harvesting ^[2] every year which reviews the past developments and current state of the technology .

The use of piezoelectric materials to harvest power has already become popular. Piezoelectric materials have the ability to transform mechanical strain energy into electrical charge. Piezo elements are being embedded in walkways ^{[3] [4]} to recover the "people energy" of footsteps. They can also be embedded in shoes ^[5] to recover "walking energy".

Pyroelectric energy harvesting

The pyroelectric effect converts a temperature change into electrical current or voltage. It is analogous to the piezoelectric effect, which is another type of ferroelectric behavior. Like piezoelectricity, pyroelectricity requires time-varying inputs and suffers from small power outputs in energy harvesting applications. One key advantage of pyroelectrics over thermoelectrics is that many pyroelectric materials are stable up to 1200 C or more, enabling energy harvesting from high temperature sources and thus increasing thermodynamic efficiency. There is a pyroelectric scavenging device that was recently introduced, however, that doesn't require time-varying inputs. The energy-harvesting device uses the edge-depolarizing electric field of a heated pyroelectric to convert heat energy into mechanical energy instead of drawing electric current off two plates attached to the crystal-faces. Moreover, stages of the novel pyroelectric heat engine can be cascaded in order to improve the Carnot efficiency. ^[6]

Thermoelectrics

In 1821, Thomas Johann Seebeck discovered that a thermal gradient formed between two dissimilar conductors produces a voltage. At the heart of the thermoelectric effect is the fact that a temperature gradient in a conducting material results in heat flow; this results in the diffusion of charge carriers. The flow of charge carriers to the low-temperature region in turn creates a voltage difference. In 1834, Jean Charles Athanase Peltier discovered that running an electric current through the junction of two dissimilar conductors could, depending on the direction of current flow, act as a heater or coolant. The heat absorbed or produced is proportional to the current, and the proportionality constant is known as the Peltier coefficient. Today, due to knowledge of the Seebeck and Peltier effects, thermocouples exist as both heaters and coolers.

Ideal thermoelectric materials have a high Seebeck coefficient, high electrical conductivity, and low thermal conductivity. Low thermal conductivity is necessary to maintain a high thermal gradient at the junction. Standard thermoelectric modules manufactured today consist of P- and N-doped bismuth-telluride semiconductors sandwiched between two metallized ceramic plates. The ceramic plates add rigidity and electrical insulation to the system. The semiconductors are connected electrically in series and thermally in parallel.

Miniature thermocouples have been developed that convert body heat into electricity and generate 40µW at 3V with a 5 degree temperature gradient, while on the other end of the scale, large thermocouples are used in nuclear RTG batteries.

Advantages to thermoelectrics:

1. No moving parts allow continuous operation for many years. Tellurex (a thermoelectric production company) claims that thermoelectrics are capable of over 100,000 hours of steady state operation.
2. Thermoelectrics contain no materials that must be replenished.
3. Heating and cooling can be reversed.

One downside to thermoelectric energy conversion is low efficiency (currently less than 10%). The development of materials that are able to operate in higher temperature gradients, and that can conduct electricity well without also conducting heat (something that was until recently thought impossible), will result in increased efficiency.

Future work in thermoelectrics could be to convert wasted heat, such as in automobile engine combustion, into electricity.

Electrostatic (capacitive) energy harvesting

This type of harvesting is based on the changing capacitance of vibration-dependent varactors. Vibrations separate the plates of an initially charged varactor (variable capacitor), and mechanical energy is converted into electrical energy.

Future directions

Electroactive polymers (EAPs) have been proposed for harvesting energy. 1111111111111111ese polymers have a large strain, elastic energy density, and high energy conversion efficiency. The total weight of systems based on EAPs is proposed to be significantly lower than those based on piezoelectric materials.