The Forest in the Sky

he ultimate green architecture project is underway in Milan, Italy. These two towers will be the first constructions to house not only people, but living trees. The towers are dubbed Bosco Verticale -- which translates to "Vertical Forest."

The towers, according to the website of the designer Stefano Boeri are "a project for metropolitan reforestation that contributes to the regeneration of the environment and urban biodiversity without the implication of expanding the city upon the territory." Each 27-story tower will house 900 trees including oaks and amelanchier as well as a wide range of shrubs and floral plants.

Were this forest to be on land it would cover a little over six square miles. The towers will use the latest in green technologies including water reclamation, wind and solar.

Beroni's website says, "The diversity of the plants and their characteristics produce humidity, absorb CO2 and dust particles, [while] producing oxygen and protecting from radiation and acoustic pollution; [thus] improving the quality of living spaces and saving energy."

by "environment clean generations"

5 Biggest Nuclear Reactors

In December of 1942, an experiment that would change the world was taking place at the University of Chicago. After years of research and a month of construction, the world's first nuclear reactor, Chicago Pile-1, was ready for testing. Constructed of a lattice of uranium and graphite blocks stacked 57 layers high, Chicago Pile-1 bore little resemblance to today's nuclear reactors. A three person "suicide squad" was waiting to step in and shut the reactor down in case the reactor's safety features failed. Fortunately, the 50 people in attendance that day were able to share a collective sigh of relief -- as the squad was not needed. The reactor worked without a hitch, and the nuclear era was born.

Today, more than 400 nuclear power plants are located in 30 countries across the globe. Together, these plants produce 15 percent of the world's electricity and 2 percent of the world's total power supply [source: World Nuclear Association]. Nuclear power certainly has its pros and cons, but no one can deny its importance. So now that we know a little about how far nuclear power has come over the past 60 years, we're ready to take a look at the five biggest nuclear reactors on Earth, starting with a couple of reactors that might not be around much longer. 

Today, more than 400 nuclear power plants are located in 30 countries across the globe. See more nuclear power pictures.

  

5: Isar II

Germany has long had an uneasy relationship with nuclear energy. While the country currently depends on nuclear energy for nearly 20 percent of its electricity, concerns about plant safety and nuclear waste storage have resulted in plans to close some of the country's largest reactors. Included on that list are two reactors located in Essenbach, Germany. Together the reactors, known as Isar I and Isar II, generate enough electricity to power more than 1.5 million households each year [source: Nuclear Energy Institute].

 

But Isar II is the reason the reactors are on this list. The reactor, commissioned in 1988, has a net installed electric capacity of 1,400 megawatts [source: E.ON]. According to E.ON, the Germany utility company that runs Isar II, creating that electricity using fossil fuels would add 12 million tons (11 million metric tons) of carbon dioxide to the environment [source: Crowley]. Perhaps that explains why some are rethinking the current plan to decommission Isar I in 2011 and its bigger brother in 2020. Read on to learn about another German reactor that's inspired more than its share of controversy. 

4: Brokdorf

On the banks of the river Elbe, sheep graze lazily on fields of lush green grass, entirely unimpressed with the massive nuclear reactor located only 100 feet (30 meters) away. Brokdorf reactor, which takes its name from the surrounding city, houses more than 110 tons (100 metric tons) of uranium [source: E.ON]. Construction on the plant began in 1981, and by 1986, the plant was operational. One of the world's largest reactors, Brokdorf claimed the title of World Champion of gross annual output in both 1992 and 2005 [source: E.ON]. With an impressive net installed electric capacity of 1,410 megawatts, Brokdorf could easily recapture the title before its scheduled decommissioning in 2018 [source: E.ON].

Brokdorf's electrical capacity makes the reactor the largest in Germany. So perhaps it's fitting that, throughout the 1980s, it was also the site of the country's largest protests against nuclear power. The protests drew tens of thousands of people a day at their peak. The demonstrations often turned violent, with protestors hurling bricks, bottles and even gasoline bombs at riot police, prompting the police to respond with tear gas and mass arrests. Hundreds of injuries resulted, affecting both citizens and riot police alike. Today, the site still draws a few peaceful protestors, but as concerns rise over global warming and increasing energy costs, Germany's attitude toward nuclear power appears to be shifting. Of course, not all countries have had such a contentious relationship with nuclear power. The next reactor on our list is located in a country that gets more of its electricity from nuclear power than any other country on Earth. 

3: Civaux 1 and 2

"No oil, no gas, no coal, no choice." The phrase has become a mantra explaining French support of nuclear power. As instability in the Middle East forced oil prices higher and higher throughout the 1960s, France recognized a need to move away from its fossil-fuel-burning power plants. Today, the country has 59 nuclear reactors responsible for producing 76 percent of France's electricity, and two reactors located in the city of Civaux are among its largest. Fully operational in 1999, Civaux 1 and Civaux 2 cost an estimated $4.1 billion to construct [source: Power-Technology].

While that's a hefty price tag, reactors in other countries can be much more expensive. In fact, power produced by Civaux 1 and Civaux 2 costs about as much as traditionally cheaper electricity generated from coal and natural gas. Turbines in the reactors are more than half a football field in length and weigh nearly 3,000 tons (2,722 metric tons), which helps explain how each of the Civaux reactors produces 1,450 megawatts (net) [source: Power-Technology].

The reactors have some impressive safety features as well, including the ability to shut down in only 2.15 seconds. Even so, Civaux 1 was closed for nearly a year after coolant leaks were discovered. The pipe work was replaced and the reactor was ready to come back online when regulators discovered a problem with harmful bacteria forming in the cooling circuits of similar reactors. To address the problem, engineers added an ultraviolet treatment system capable of killing the bacteria. Now both Civaux 1 and Civaux 2 are up and running, helping France to power not only its own homes and businesses but even export energy to neighboring countries. 

2: Chooz B1 and 2

Like their sister reactors in Civaux, the two reactors known as Chooz B1 and Chooz B2 are part of France's series of technologically advanced N4 reactors. Among the technological innovations are computerized control rooms that provide operators detailed information about the reactors' systems, as well as very efficient steam generators and cooling pumps. Yet even with the advanced technology, Chooz B1 took only 12 years to construct. Even more impressive, the Chooz B reactors have a net installed electric capacity of 1,455 megawatts [source: Davis]. That makes the reactors the most powerful in the world in terms of individual output, capable of generating more than 5 percent of France's nuclear power [sources: Areva].

The advanced technology behind the N4 reactors caused some problems, however; like the reactors in Civaux, Chooz B1 and Chooz B2 had some problems during early operations. They shared the same faulty cooling design as Civaux 1 and 2, for instance, so the reactors were taken offline for a year as their systems were redesigned and replaced. For the time being, though, the kinks seem to be worked out and all four N4 reactors are fully operational.

And if providing a huge portion of France's electricity isn't enough, the Chooz reactors may even provide some perspective on the very nature of matter itself. In July 2009, the construction of a laboratory on the site of the Chooz B reactors was announced. The lab, designed to study the elusive neutrino, could give scientists insight into the very origins of the universe itself.

The next reactors on our list may not solve any scientific mysteries, but in terms of sheer power, they can't be beat. Read on to find out more. 

1: Kashiwazaki-Kariwa

Japan's Kashiwazaki-Kariwa reactors, which were completed in 1997, won't break any records for individual output, but their combined electrical output is uncontested. The power plant, which has seven separate reactors, has a rated capacity of 8,212 megawatts. That's enough capacity to power more than 16 million households each year, providing more than 5 percent of Japan's total electricity [source: Power-Technology].

The Kashiwazaki-Kariwa reactors, like all Japanese reactors, were constructed with extensive safety mechanisms designed to withstand Japan's frequent earthquakes. 

The plant extends deep into the surrounding water where it attaches to the solid ground below, providing a sturdy foundation to withstand shocks. Even so, the reactors were taken offline after a magnitude 6.8 earthquake struck the plant in July of 2007. The earthquake caused extensive damage to the plants, including fires and radiation leaks, though many expected the damage to be much worse. As of today, most of the reactors remain offline as regulators inspect the plants for further damage, though some of the reactors have received approval to resume operation.

by "environment clean generations"

 

Let's Lock That CO2 In A Rock

HELLISHEIDI, Iceland (AP) — Sometime next month, on the steaming fringes of an Icelandic volcano, an international team of scientists will begin pumping "seltzer water" into a deep hole, producing a brew that will lock away carbon dioxide forever.

Chemically disposing of CO2, the chief greenhouse gas blamed for global warming, is a kind of 21st-century alchemy that researchers and governments have hoped for to slow or halt climate change.

The American and Icelandic designers of the "CarbFix" experiment will be capitalizing on a feature of the basalt rock underpinning 90 percent of Iceland: It is a highly reactive material that will combine its calcium with a carbon dioxide solution to form limestone — permanent, harmless limestone.

The researchers caution that their upcoming 6-to-12-month test could fall short of expectations, and warn against looking for a climate "fix" from CarbFix any year soon.

In fact, one of the objectives of the project, whose main sponsors are Reykjavik's city-owned utility and U.S. and Icelandic universities, is to train young scientists for years of work to come.

A scientific overseer of CarbFix — the man, as it happens, who also is credited with coining the term "global warming" four decades ago — says the world's failure to heed those early warnings, to rein in greenhouse-gas emissions from coal, gasoline and other fossil fuels, is driving scientists to drastic approaches.

"Whether we do it in the next 50 years, or the 50 years after that, we're going to have to store carbon dioxide," Columbia University's Wallace S. Broecker said in an interview in New York.

The world is already storing some carbon dioxide. As a byproduct of Norway's natural gas production, for example, it is being pumped into a sandstone reservoir beneath the North Sea.

But people worry that such stowed-away gas could someday escape, while carbon dioxide transformed into stone would not.

The experimental transformation will take place below the dramatic landscape of this place 29 kilometers (18 miles) southeast of Reykjavik, Iceland's capital. On an undulating, mossy moor and surrounding volcanic hills, where the last eruption occurred 2,000 years ago, Reykjavik Energy operates a huge, 5-year-old geothermal power plant, drawing on 30 wells tapping into the superheated steam below, steam laden with carbon dioxide and hydrogen sulfide.

CarbFix will first separate out those two gases, and the CO2 will be piped 3 kilometers (2 miles) to the injection well, to combine with water pumped from elsewhere.

That carbonated water — seltzer — will be injected down the well, where the pressure of the pumped water, by a depth of 500 meters (1,600 feet), will completely dissolve the CO2 bubbles, forming carbonic acid.

"The acid's very corrosive, so it starts to attack the rocks," explained University of Iceland geologist Sigurdur Reynir Gislason, CarbFix's chief scientist.

The basalt rock — ancient lava flows — is porous, up to 30 percent open space filled with water. The carbonic acid will be pushed out into those pores, and over time will react with the basalt's calcium to form calcium carbonate, or limestone.

CarbFix's designers, in effect, are radically speeding up the natural process called weathering, in which weak carbonic acid in rainwater transforms rock minerals over geologic time scales.

The CarbFix team, beginning work in 2007, had to overcome engineering challenges, particularly in the inventive design and operation of the gas separation plant. They have applied for U.S. and Icelandic patents for that and for the injection well technique.

They plan to inject up to 2,000 tons of carbon dioxide over 6 to 12 months and then follow how far the solution is spreading via tracer elements and monitoring wells. Eventually they plan to drill into the rock to take a core sampling.

"It will take months and years to test how well it has spread," Reykjavik Energy's Bergur Sigfusson, project technical manager, said as he guided two AP journalists through the step-by-step process over the rolling green terrain of the Hengill volcano.

The team's greatest concern is that carbon "mineralization" may happen too quickly.

"If it reacts too fast, then that will clog up the system," Sigfusson explained. Quick formation of calcium carbonate would block too many paths through the basalt for the solution to spread.

If it works on a large scale, scientists say, carbon mineralization has a limitless potential, since huge basalt deposits are common — in Siberia, India, Brazil and elsewhere. One formation lies beneath the U.S. northwest, where the U.S. Pacific Northwest National Laboratory plans an experiment similar to CarbFix.

The long-term challenge then becomes capturing the carbon dioxide, and building the infrastructure to deliver it to the right places.

At a basic level, the CarbFix process might at least allow geothermal plants worldwide to neutralize their carbon emissions. At another level, "you'd line up the coal-fired power plants where the basalt is," said Gislason. Their CO2 then could be locked away permanently as rock, rather than stored in underground cavities as now generally conceived.

But ultimately "my vision for carbon capture and storage is offshore, below the sea. The whole ocean floor is basalt below the sediments," said Swiss geochemist and CarbFix manager Juerg Matter, who works with Broecker at Columbia's Lamont-Doherty Earth Observatory.

That futuristic vision would likely require technology to take carbon dioxide from the atmosphere itself — perhaps via millions of chemically treated vanes standing in the wind, a technique being investigated. Such units could be located offshore, with the captured CO2 piped to basalt below, Matter said.

In Gislason's Reykjavik university laboratories, young scientists are already conducting experiments with seawater and basalt, "and they're very promising," the chief scientist said.

"In 10, 20, 30 years' time, if climate change gets very drastic, then we are going to need solutions like this," he said of CarbFix. "We are going to need solutions 'yesterday.'"

Reykjavik Energy has supplied almost half the $10 million spent thus far on CarbFix. Other funding comes from the two universities, France's National Center of Scientific Research, the U.S. Energy Department, the European Union and Scandinavian sources.

by "environment clean generations"

The Zero-Emissions Dice House

Roll the Dice The building’s designer, Sybarite, hopes to make its design the standard for zero-emissions homes. Courtesy Sybarite House