Wind and wave energies are not renewable after all

Build enough wind farms to replace fossil fuels and we could do as much damage to the climate as greenhouse global warming

Witness a howling gale or an ocean storm, and it's hard to believe that humans could make a dent in the awesome natural forces that created them. Yet that is the provocative suggestion of one physicist who has done the sums.

He concludes that it is a mistake to assume that energy sources like wind and waves are truly renewable. Build enough wind farms to replace fossil fuels, he says, and we could seriously deplete the energy available in the atmosphere, with consequences as dire as severe climate change.

Axel Kleidon (at right) of the Max Planck Institute for Biogeochemistry in Jena, Germany, says that efforts to satisfy a large proportion of our energy needs from the wind and waves will sap a significant proportion of the usable energy available from the sun. In effect, he says, we will be depleting green energy sources. His logic rests on the laws of thermodynamics, which point inescapably to the fact that only a fraction of the solar energy reaching Earth can be exploited to generate energy we can use.

When energy from the sun reaches our atmosphere, some of it drives the winds and ocean currents, and evaporates water from the ground, raising it high into the air. Much of the rest is dissipated as heat, which we cannot harness.

At present, humans use only about 1 part in 10,000 of the total energy that comes to Earth from the sun. But this ratio is misleading, Kleidon says. Instead, we should be looking at how much useful energy - called "free" energy in the parlance of thermodynamics - is available from the global system, and our impact on that. (Left - to see larger image please click on image)

Humans currently use energy at the rate of 47 terawatts (TW) or trillions of watts, mostly by burning fossil fuels and harvesting farmed plants, Kleidon calculates in a paper to be published in Philosophical Transactions of the Royal Society. This corresponds to roughly 5 to 10 per cent of the free energy generated by the global system.

"It's hard to put a precise number on the fraction," he says, "but we certainly use more of the free energy than [is used by] all geological processes." In other words, we have a greater effect on Earth's energy balance than all the earthquakes, volcanoes (Mount St. Helens eruption) and tectonic plate movements put together.

Radical as his thesis sounds, it is being taken seriously. "Kleidon is at the forefront of a new wave of research, and the potential prize is huge," says Peter Cox, who studies climate system dynamics at the University of Exeter, UK. "A theory of the thermodynamics of the Earth system could help us understand the constraints on humankind's sustainable use of resources." Indeed, Kleidon's calculations have profound implications for attempts to transform our energy supply.

Of the 47 TW of energy that we use, about 17 TW comes from burning fossil fuels. So to replace this, we would need to build enough sustainable energy installations to generate at least 17 TW. And because no technology can ever be perfectly efficient, some of the free energy harnessed by wind and wave generators will be lost as heat. So by setting up wind and wave farms, we convert part of the sun's useful energy into unusable heat.

"Large-scale exploitation of wind energy will inevitably leave an imprint in the atmosphere," says Kleidon. "Because we use so much free energy, and more every year, we'll deplete the reservoir of energy." He says this would probably show up first in wind farms themselves, where the gains expected from massive facilities just won't pan out as the energy of the Earth system is depleted.

Using a model of global circulation, Kleidon found that the amount of energy which we can expect to harness from the wind is reduced by a factor of 100 if you take into account the depletion of free energy by wind farms. It remains theoretically possible to extract up to 70 TW globally, but doing so would have serious consequences.

Although the winds will not die, sucking that much energy out of the atmosphere in Kleidon's model changed precipitation, turbulence and the amount of solar radiation reaching the Earth's surface. The magnitude of the changes was comparable to the changes to the climate caused by doubling atmospheric concentrations of carbon dioxide (Earth System Dynamics, DOI: 10.5194/esd-2-1-2011).

"This is an intriguing point of view and potentially very important," says meteorologist Maarten Ambaum of the University of Reading, UK. "Human consumption of energy is substantial when compared to free energy production in the Earth system. If we don't think in terms of free energy, we may be a bit misled by the potential for using natural energy resources."

This by no means spells the end for renewable energy, however. Photosynthesis also generates free energy, but without producing waste heat. Increasing the fraction of the Earth covered by light-harvesting vegetation - for example, through projects aimed at "greening the deserts" - would mean more free energy would get stored. Photovoltaic solar cells can also increase the amount of free energy gathered from incoming radiation, though there are still major obstacles to doing this sustainably.

In any event, says Kleidon, we are going to need to think about these fundamental principles much more clearly than we have in the past. "We have a hard time convincing engineers working on wind power that the ultimate limitation isn't how efficient an engine or wind farm is, but how much useful energy nature can generate." As Kleidon sees it, the idea that we can harvest unlimited amounts of renewable energy from our environment is as much of a fantasy as a perpetual motion machine.

Read more on solar energy (may require subscription)........

Source:
The New Scientist,"Wind and wave energies are not renewable after all", accessed April 1, 2011

Navajos Hope to Shift From Coal to Wind and Sun

For decades, coal has been an economic lifeline for the Navajos, even as mining and power plant emissions dulled the blue skies and sullied the waters of their sprawling reservation. (Left: Supporters of Earl Tulley and Lynda Lovejoy at a campaign rally last month in Blue Gap, Ariz.)

But today there are stirrings of rebellion. Seeking to reverse years of environmental degradation and return to their traditional values, many Navajos are calling for a future built instead on solar farms, eco-tourism and micro-businesses.

“At some point we have to wean ourselves,” Earl Tulley, a Navajo housing official, said of coal as he sat on the dirt floor of his family’s hogan, a traditional circular dwelling.

Mr. Tulley, who is running for vice president of the Navajo Nation in the Nov. 2 election, represents a growing movement among Navajos that embraces environmental healing and greater reliance on the sun and wind, abundant resources on a 17 million-acre reservation spanning Arizona, New Mexico and Utah.

“We need to look at the bigger picture of sustainable development,” said Mr. Tulley, the first environmentalist to run on a Navajo presidential ticket.

With nearly 300,000 members, the Navajo Nation is the country’s largest tribe, according to Census Bureau estimates, and it has the biggest reservation. Coal mines and coal-fired power plants on the reservation and on lands shared with the Hopi provide about 1,500 jobs and more than a third of the tribe’s annual operating budget, the largest source of revenue after government grants and taxes.

At the grass-roots level, the internal movement advocating a retreat from coal is both a reaction to the environmental damage and the health consequences of mining — water loss and contamination, smog and soot pollution — and a reconsideration of centuries-old tenets.

In Navajo culture, some spiritual guides say, digging up the earth to retrieve resources like coal and uranium (which the reservation also produced until health issues led to a ban in 2005) is tantamount to cutting skin and represents a betrayal of a duty to protect the land.

“As medicine people, we don’t extract resources,” said Anthony Lee Sr., president of the Diné Hataalii Association, a group of about 100 healers known as medicine men and women.

But the shift is also prompted by economic realities. Tribal leaders say the Navajo Nation’s income from coal has dwindled 15 percent to 20 percent in recent years as federal and state pollution regulations have imposed costly restrictions and lessened the demand for mining.

Two coal mines on the reservation have shut down in the last five years. One of them, the Black Mesa mine, ceased operations because the owners of the power plant it fed in Laughlin, Nev., chose to close the plant in 2005 rather than spend $1.2 billion on retrofitting it to meet pollution controls required by the Environmental Protection Agency.
Early this month, the E.P.A. signaled that it would require an Arizona utility to install $717 million in emission controls at another site on the reservation, the Four Corners Power Plant in New Mexico (left), describing it as the highest emitter of nitrous oxide of any power plant in the nation. It is also weighing costly new rules for the Navajo Generating Station in Arizona.

And states that rely on Navajo coal, like California, are increasingly imposing greenhouse gas emissions standards and requiring renewable energy purchases, banning or restricting the use of coal for electricity.

So even as they seek higher royalties and new markets for their vast coal reserves, tribal officials say they are working to draft the tribe’s first comprehensive energy policy and are gradually turning to casinos, renewable energy projects and other sources for income.

This year the tribal government approved a wind farm to be built west of Flagstaff, Ariz., to power up to 20,000 homes in the region. Last year, the tribal legislative council also created a Navajo Green Economy Commission to promote environmentally friendly jobs and businesses.

“We need to create our own businesses and control our destiny,” said Ben Shelly, the Navajo Nation vice president, who is now running for president against Lynda Lovejoy, a state senator in New Mexico and Mr. Tulley’s running mate.

That message is gaining traction among Navajos who have reaped few benefits from coal or who feel that their health has suffered because of it.

Curtis Yazzie, 43, for example, lives in northeastern Arizona without running water or electricity in a log cabin just a stone’s throw from the Kayenta mine.

Tribal officials, who say some families live so remotely that it would cost too much to run power lines to their homes, have begun bringing hybrid solar and wind power to some of the estimated 18,000 homes on the reservation without electricity. But Mr. Yazzie says that air and water pollution, not electricity, are his first concerns.

“Quite a few of my relatives have made a good living working for the coal mine, but a lot of them are beginning to have health problems,” he said. “I don’t know how it’s going to affect me.”

One of those relatives is Daniel Benally, 73, who says he lives with shortness of breath after working for the Black Mesa mine (left) in the same area for 35 years as a heavy equipment operator. Coal provided for his family, including 15 children from two marriages, but he said he now believed that the job was not worth the health and environmental problems.

“There’s no equity between benefit and damage,” he said in Navajo through a translator.

About 600 mine, pipeline and power plant jobs were affected when the Mohave Generating Station in Nevada and Peabody’s Black Mesa mine shut down.

But that also meant that Peabody stopped drawing water from the local aquifer for the coal slurry carried by an underground pipeline to the power plant — a victory for Navajo and national environmental groups active in the area, like the Sierra Club.

Studies have shown serious declines in the water levels of the Navajo aquifer after decades of massive pumping for coal slurry operations. And the E.P.A. has singled out the Four Corners Power Plant and the Navajo Generating Station as two of the largest air polluters in the country, affecting visibility in 27 of the area’s “most pristine and precious natural areas,” including the Grand Canyon.

The regional E.P.A. director, Jared Blumenfeld, said the plants were the nation’s No. 1 and No. 4 emitters of nitrogen oxides, which form fine particulates resulting in cases of asthma attacks, bronchitis, heart attacks and premature deaths.

Environmentalists are now advocating for a more diversified Navajo economy and trying to push power plants to invest in wind and solar projects.

“It’s a new day for the Navajo people,” said Lori Goodman, an official with Diné Citizens Against Ruining Our Environment, a group founded 22 years ago by Mr. Tulley. “We can’t be trashing the land anymore.”

Both presidential candidates in the Navajo election have made the pursuit of cleaner energy a campaign theme, but significant hurdles remain, including that Indian tribes, as sovereign entities, are not eligible for tax credits that help finance renewable energy projects elsewhere.

And replacing coal revenue would not be easy. The mining jobs that remain, which pay union wages, are still precious on a reservation where unemployment is estimated at 50 percent to 60 percent.

“Mining on Black Mesa,” Peabody officials said in a statement, “has generated $12 billion in direct and implied economic benefits over the past 40 years, created thousands of jobs, sent thousands of students to college and restored lands to a condition that is as much as 20 times more productive than native range.”

They added, “Renewables won’t come close to matching the scale of these benefits.”

But many Navajos see the waning of coal as inevitable and are already looking ahead. Some residents and communities are joining together or pairing with outside companies to pursue small-scale renewable energy projects on their own.

Wahleah Johns, a member of the new Navajo Green Economy Commission,is studying the feasibility of a small solar project on reclaimed mining lands with two associates. In the meantime, she uses solar panels as a consciousness-raising tool.

“How can we utilize reclamation lands?” she said to Mr. Yazzie during a recent visit as they held their young daughters in his living room. “Maybe we can use them for solar panels to generate electricity for Los Angeles, to transform something that’s been devastating for our land and water into something that can generate revenue for your family, for your kids.”

Mr. Yazzie, who lives with his wife, three children and two brothers, said he liked the idea. “Once Peabody takes all the coal out, it’ll be gone,” he said. “Solar would be long-term. Solar and wind, we don’t have a problem with. It’s pretty windy out here.”

Source:
New York Times, "Navajos Hope to Shift From Coal to Wind and Sun", accessed October 26, 2010

Sahara solar energy could power Europe

The Sahara gets twice as much sunshine annually as most of Europe. The European Union wants to get 20 percent of its electricity from renewable sources within a decade. So why not build solar power plants across North Africa and ship the electricity north via power lines under the Mediterranean?

Over the past year, more than 30 European companies have joined the Desertec Industrial Initiative, a consortium that seeks a $560 billion investment in North African solar and wind installations over the next 40 years. The group is completing a feasibility study and hopes to be building its first power plant by 2013. (Right: Desertec proposed map; click for larger image)

A separate group of companies called Transgreen, formed in July, is working on plans for the thousands of miles of high-voltage lines needed. The challenge is immense: Winning agreement from very different countries on two continents to carry out one of the biggest infrastructure projects in history.

Construction contracts

Many backers are eager for a share of rich construction contracts. They include engineering outfits such as Germany's Siemens and Swiss-Swedish group ABB and solar companies Abengoa Solar of Spain and First Solar of Arizona. Giant Italian utility Enel wants to rely less on Russian gas, and German insurer Munich Re sees the project as a hedge against damage from global warming. (Abengoa solar project at right)

"We are creating a large network of allies with complementary interests," said Desertec boss Paul van Son, a former Dutch utility executive.

There's little doubt that Sahara sun can power Europe. Cables already carry electricity under the Mediterranean - though the power flows from Spain to Morocco. And after years of false starts, scores of large-scale solar power plants are being built or in advanced planning stages, from the American Southwest to the Mideast.

"There is now a good track record," said Bernd Utz, head of Siemens' renewable energy division.

With the technology the consortium plans to use, solar-powered electricity costs at least four times as much per kilowatt-hour as power from coal- and gas-fired plants, according to Bloomberg New Energy Finance, an analysis group. Governments have used subsidies to support alternate energy companies until their costs are more in line with oil and gas. The United States awarded a $1.45 billion loan guarantee in July to reduce financing costs for the planned Solana power plant in Arizona (right), at 280 megawatts one of the world's largest.

The Sahara project envisions generating capacity equal to almost 400 Solanas. Where would the financing come from? Desertec and Transgreen member companies so far have put up less than $10 million for feasibility studies. They want Europe's governments to require utilities to pay more for Sahara-generated energy, a preferential arrangement that European countries use to spur solar and wind energy development at home.

Trouble is, Germany and Spain are reducing these rates, which the utilities often pass on to customers. The depth of political support in North Africa is another issue. Morocco, Tunisia, and Egypt back the project. Algeria wants to develop solar plants on its own. Some European critics, meanwhile, see a case of overreach.

"European countries can develop faster and cheaper than Desertec a renewable energy supply from indigenous sources," said Hermann Scheer, a member of the German Bundestag who heads Eurosolar, a solar research and advocacy group in Bonn.

Even Europe's sunniest regions, though, don't get enough sun to generate power as efficiently as in North Africa, says Abengoa Solar Chief Executive Officer Santiago Seage.

Room for mirrors

The Sahara's ample space is crucial because plans call for fields of mirrors, totaling hundreds of square miles, at more than 20 locations. The mirrors would concentrate the sun's rays to create heat and drive turbines - a technology known as concentrating solar power or CSP, that allows heat to be extracted and stored gradually so electricity is generated continuously. Plans also call for solar photovoltaic and wind turbine generators, whose energy costs less to produce than concentrating solar power but yet don't offer storage capacity.

"For utilities, CSP is a much more robust product," Seage said. (At right)

As the consortium feels its way forward, some European countries could strike bilateral deals with North African suppliers. Morocco, for example, has announced plans to build solar plants for its own use. Because Morocco's government can't afford the subsidies that would make solar power feasible inside its own borders, it might team up with Spain or France to help with financing in exchange for a share of output, suggests Logan Goldie-Scot, a London analyst with Bloomberg New Energy Finance.

"The (Desertec) project will happen," he said, but "it's likely to be a series of small projects."

Source:
San Francisco Chronicle, "Sahara solar energy could power Europe", accessed September 15, 2010