SIEBEN LINDEN, Germany (CNN) -- Straw and clay are the building materials of choice for a few dozen ecologically minded people in the eastern German village of Sieben Linden.
Cleverly insulated homes in part of Freiburg, Germany, use a fraction of the energy consumed in average homes.
A continent away, the Chinese government plans to transform a rural area of 100,000 people into a city of 400,000 that would run largely on renewable energy.
From the simplest methods to the most technologically advanced, the strategies employed around the world to be more environmentally friendly and reduce reliance on fossil fuels are as varied as the people that inhabit the planet.
One city garnering international attention is Freiburg, in southern Germany. Its use of solar panels and other forms of renewable energy draws tourists interested in taking green ideas to their hometowns.
A Freiburg neighborhood, the Schlierberg Solar Village, consists of solar-powered abodes insulated in such a way that they use only 10 percent of the energy consumed in average homes. Solar-Fabrik, a producer of solar panels, has a sun-powered factory in Freiburg. Watch how Freiburg uses solar energy »
Jerome Barrier recently visited to get tips for his home in France.
"You have sustainable development housing estates, you have ... design centers [and] research centers," Barrier said. "In two days, you can see all the technologies and, I would say, all the tricks that we can implement where we come from."
Solar power accounts for only 2 percent of Freiburg's energy supply. Still, many see the city as a pioneer in solar technology. The local soccer club, SC Freiburg, runs its stadium largely with solar energy and power converted from wood chips.
People who use solar panels to power their homes sometimes produce more energy than they use. In Germany, such unused power is transferred to the local utility, which buys it from the homeowners at a government-subsidized rate. iReport.com: How are you going green?
Strong demand for solar technology in Germany has contributed to a global shortage of a key panel component -- silicon -- making solar technology more expensive. Freiburg's mayor, Dieter Salomon, said solar power isn't necessarily the best energy choice.
"It's a symbol, it's not the big shot," he said. "I think the future of photovoltaic [solar energy] will be in the less developed countries."
Sieben Linden, the village in eastern Germany, mixes high- and low-tech approaches. Some of its roughly 100 residents live in homes built with little more than clay, wood and straw.
Straw bales coated with clay are put inside the homes' walls. The insulation reduces the need for powered heating and cooling, making the houses much more energy efficient than homes made with standard building materials, according to village resident Martin Schlegel. Watch home construction in the village »
"The energy you save by [using straw] is sufficient to heat this house 12 years, compared to a house built with normal modern materials," he said.
Those who worry about the straw easily catching fire should think again, Schlegel said. He said that because the bales are tightly packed, they don't ignite quickly.
"[Burning] a sheet of paper -- it is very easy. But try to light a telephone book," he said, comparing the bales to the book.
Straw-bale construction was used in Nebraska in the 19th century. The villagers of Sieben Linden take a more technological approach, fitting their homes with solar panels.
"Environmentally sound living always involves high tech," villager Werner Dyck said. "The solar panels are high tech, and we have computers to make them even more efficient to manage our energy needs."
In China, government and Western developers plan to convert the rural area of Wanzhuang, near Beijing, into an "ecocity" -- one of the nation's first.
The plan, according to United Kingdom-based developer Arup, is to have the city running largely on renewable energy by 2020. Watch an explanation of developers' plans »
A tram system will be introduced to reduce residents' reliance on cars. About 300,000 more people will move to the area, which is now known for its pear orchards and is now home to 100,000 people.
The orchards will be preserved, and schools, offices and shops will be placed in a manner to reduce travel needs, developers say.
Critics may note that the effort wouldn't be significant for China, citing estimates it opens a new coal power plant every week, emitting more environmentally damaging carbon.
Peter Head, an Arup architect, said the ecocity project is valuable.
"If China doesn't pursue this modernization process using ecocities, its economic growth will become uneconomic," he said.
In the Middle East, the emirate of Abu Dhabi -- a major oil producer -- is spending $15 billion to make itself an epicenter of green technology.
Part of its plans include building a 2-square-mile eco-community -- called Masdar -- over the next 10 years. Air cooling alone is quite an energy-consuming task in the sunny Persian Gulf emirate, but developers say the city can be run on energy from the sun, wind and biofuels refined from plants and waste. Watch an explanation of the Masdar plan »
Water will be purified by solar power and recycled from the sea for both consumption and farming. About 40,000 people will live there, and another 50,000 will work there, organizers say.
Abu Dhabi's green ambitions don't end with the city. It has persuaded the Massachusetts Institute of Technology to create the Masdar Institute of Science and Technology, a graduate school and research institute focused exclusively on renewable energy.
Abu Dhabi wants to position itself as a global center for harnessing new fuels for a time when oil won't be as plentiful.
"It's no longer the issue of pumping oil out of the ground. It's the issue of competing globally for the same issues, and for that, they need highly trained people," MIT professor Fred Moavenzadeh said.
CNN's Diana Magnay, Frederik Pleitgen, Emily Chang and Jennifer Eccleston contributed to this report.