Stories tagged Stanford University

Sep
05
2010

Cotton for filters
Cotton for filtersCourtesy Martin Labar

Safe drinking water saves lives

Clean, safe drinking is desperately needed throughout the world. Usually filters "filter out" bacteria by having openings too small to get through. Trouble is, though, that the tiny holes get plugged up, stopping the flow of water. Stanford researchers have now developed a filter about 80,000 times faster than filters that trap bacteria.

Cheap and easy

The filter was made by dipping plain cotton cloth (from Walmart) in a mixture of silver nanowires and carbon nanotubes (for a few minutes). By charging the filter with 20 volts of electricity, over 98 percent of Escherichia coli bacteria were killed as they passed through. Even in remote or primitive areas, the electricity could be supplied by a small solar panel, or a couple 12-volt car batteries, or be generated from a stationary bicycle or by a hand-cranked device.

Cui said the next steps in the research are to try the filter on different types of bacteria and to run tests using several successive filters.
"With one filter, we can kill 98 percent of the bacteria," Cui said. "For drinking water, you don't want any live bacteria in the water, so we will have to use multiple filter stages."

Learn more
High-speed filter uses electrified nanostructures to purify water at low cost Stanford University News

Jun
25
2010

Agriculture is widely understood to be one of the largest contributors of greenhouse gases in our atmosphere, which is unfortunate for two reasons: 1) greenhouse gases are a driving force of climate change, and 2) last time I checked, people still need to eat.

Literally Green Skyscrapers: In a near-future world with 9 billion people, land will be even more valuable than it is today.  Researchers have been asking themselves how we are going to feed all those new people...  What if we built high rise greenhouses?
Literally Green Skyscrapers: In a near-future world with 9 billion people, land will be even more valuable than it is today. Researchers have been asking themselves how we are going to feed all those new people... What if we built high rise greenhouses?Courtesy Curbed SF

Specifically, farming is one of the largest contributors of carbon dioxide, methane, and nitrous oxide – all greenhouse gases – in our atmosphere. The four major sources of these emissions include fossil fuel consumption, fertilizer usage, animal farts and poop (no kidding!), as well as land use change (mainly, deforestation). As serious a problem as climate change is, one of the most important truths for environmentalists to remember is that people have needs that necessarily affect the health of the environment. For example, the world’s population is currently well over six billion people who need roughly 2,000 calories from food each day. That’s a lot of food that we depend upon farmers to raise and grow for us every day! And with predictions of nine billion people occupying the Earth in a mere forty years, our global population’s appetite is growing.

However, a June 2010 study published in Scientific American says that farming’s bad rap is undeserved, and actually modern high-yield crop farming has a net reduction of greenhouse gas emissions. Say what??

Here’s how it works: What sustainability-minded scientists from many disciplines strive to do is find ways to limit (better!) or eliminate (best!!) peoples’ negative impact on the environment.

In the 1960s, farmers and researchers began to develop new methods of farming to feed the rapidly expanding population. This has been called the “Green Revolution.” The results of their studies produced modern high-yield farming, which has allowed farmers to produce more food in less space. According to the Stanford researchers, though high-yield farming is possible largely because of fertilizer use – one of the four major sources of greenhouse gas emissions on farms – it prevents land use change in the form of deforestation – another one of the four major sources of greenhouse gas emissions on farms. The key point is that the greenhouse gas emissions caused by fertilizer use is less than the greenhouse gas emissions caused by deforestation, which yields a net reduction. That is, if we had continued with pre-Green Revolution farming techniques, in order to feed today’s population, we’d be using less fertilizer, deforesting more land, and emitting considerably more greenhouse gases than we currently are.

Today, at the Institute on the Environment, the Global Landscapes Initiative continues to focus on seeking ways to secure a healthy land use future for both people and the environment. This includes researching innovative agricultural practices.

Hydroponics: Hydoponics is a method of growing plants without soil.  Weird, but true!  Instead, plants are raised in a mineral water bath.  Could this be the future of farming?
Hydroponics: Hydoponics is a method of growing plants without soil. Weird, but true! Instead, plants are raised in a mineral water bath. Could this be the future of farming?Courtesy pchic

Another Scientific American article has it’s own ideas about how to provide food to our growing population: build vertical farms. These futuristic, skyscraping greenhouses are based upon existing hydroponic greenhouses and could reduce fossil-fuel use while simultaneously recycling city wastewater. Hydroponic greenhouses grow plants without soil! Instead, they use mineral nutrients dissolved in water, allowing plants to be grown just about anywhere… including on the 34th floor. According to the article,

“A one-square-block farm 30 stories high could yield as much food as 2,400 outdoor acres…”

That’s a lot of food. A lot. Really? Is it possible? The paper’s author claims it is and that architects, engineers, designers, and “mainstream organizations” are taking note of his vertical farm concept.