Cleantech

Green message crafting
Americans and the U.S. have a reputation of flaunting their wealth. Today, however, they are starting to proudly (sometimes loudly) show off their greenness. There's a debate over whether this is just a fad or the start of a nationwide trend to support sustainable practices.

Companies around the world are now racing to establish their credibility in green production. But they must also be careful of not being perceived as greenwashing.

On the other hand, being too inconspicuous in their efforts could hurt a company. With public awareness and demand for products that have smaller impacts on the government, companies are forced to let the public know what they've been doing.

Joel Makower writes:

Companies are being pressed to talk about what they're doing--and not doing--by customers, employees, investors, activists, and others. Previously reclusive companies are rethinking their taciturn strategies.

With the hype building up for greenness in corporate America, it may be a while until the public can properly discern the genuine stuff from noise.

Pedaling for water
Bikes have many uses including generating electricity and powering the Internet in rural villages. Some people even use it for transportation.

But a group of students in California have just developed a new use. Actually it's for a tricycle, but the idea is a foot-powered water filtration device-vehicle hybrid. Called the Aquaduct Mobile Filtration Device, the vehicle sucks water from reservoir in a rear tank and cleans it through a filtration system. The purified water is stored in a reservoir in the front.

Joshua Liberles writes in Carectomy:

Five California-based design students built the Aquaduct for rural, third-world countries where many people either walk for miles or use a motorized vehicle to retrieve water, and then use up time and energy to boil the water. The Aquaduct provides the transportation sans fossil fuel, eliminates the need for wood or other fuels to heat the water, and is emissions free.

U.S. solar check
It's been said that each of the renewable-energy sources could theoretically power the U.S. many times over if they were exploited to their full technical potential.

But how reliable are these figures? For instance, can the U.S. really get all of its electricity from the sun?

Robert Rapier, in the R-Squared Energy Blog in Green Tech Media, did a quick calculation:

Peak U.S. demand, according to the EIA, is almost 800,000 megawatts. Actual available capacity is 900,000 megawatts. So let's make our solar capacity equal to today's total installed electrical generating capacity.

Assuming the entire 1,900 acres is needed for the plant (maybe not a good assumption, but all I have), then this breaks down to 280 megawatts/1,900 acres, or 0.147 megawatts per acre. This of course includes all of the land associated with support functions, and it may include area for future expansions. So the calculation may be conservative.

The second assumption is that the areas where our plants will be put will be as productive as this one in Arizona. That is not a conservative assumption, and will somewhat offset the previous conservative calculations.

Then to get 900,000 megawatts is going to take 900,000 megawatts/0.147 megawatts per acre, or 6.1 million acres. How large of an area is this? I don't know. I have to get out my calculator.

My calculator indicates that 6.1 million acres is an area of 9,531 square miles, which is equivalent to a square of just under 100 miles by 100 miles (which would be 10,000 square miles).

Of course, this doesn't take into account transmission losses and the fact that the sun is not around 24 hours a day. Still, that is a lot of energy coming from the sun.

Just how many square miles would Las Vegas need? :)

Frank Ling is a postdoctoral fellow at the Renewable and Appropriate Energy Laboratory (RAEL) at UC Berkeley. He is also a producer of the Berkeley Groks Science Show.