Apr 24, 2011

Roads as Solar and Piezo-Electric Generators

Another use of a free, wasted byproduct to generate electricity is piezo-electric energy. "Piezo" means pressure. Anything that produces pressure can produce energy.

For example, a train station in Japan installed piezo-electric equipment in the ground, so that the foot traffic of those walking through the train station generates electricity (turnstiles at train, subway and ferry stations, ballparks and amusement parks can also generate electricity).

Similarly, all exercise machines at the gym or at home can be hooked up to produce electricity.

But perhaps the greatest untapped sources of piezo-electric energy are freeways and busy roads. If piezo-electric mats were installed under the busiest sections [a little ways under the surface], the thousands of tons of vehicles passing over each day would generate massive amounts of electricity for the city's use.

A couple of readers thought that sounded nuts.

But as TreeHugger notes today:

Denmark will have to come up with something big to match the latest plan from the Netherlands - the installation of solar panels in roads, starting with bike lanes.solar-road-design.jpg

Talk about the efficient use of space: if you're going to have roads (and hopefully you'll have bike lanes), why not put that space to work producing energy? Called the Solaroad, the project is the brainchild of Dutch research firm TNO. The idea is pretty straightforward: a layer of concrete forms the road itself. A centimeter thick layer of crystalline silicon solar cells is laid on top, and covered by a layer of toughened glass. The energy potential: 50kWh per square meter per year, which can then be used to power street lighting, traffic systems and households.

...Scheduled for installation next year, the first Solaroad will hopefully allow its developers better implement many more throughout the country.

Now why not put a piezo-electric mat under the crystalline silicon solar cells, under the layer of toughened glass?

We'd get two different forms of energy generation at once...

The U.S. Wastes More Energy Than it Uses - Partly Because of the Centralization of Power

As shown by the following graphic from Lawrence Berkeley National Laboratory, the U.S. wastes a lot more energy than it uses:

(click for giant graphic.)

America uses 39.97 quads of energy, while it wastes 54.64 quads (i.e. "rejected energy").

As CNET noted in 2007:

Sixty-two percent of the energy consumed in America today is lost through transmission and general inefficiency. In other words, it doesn't go toward running your car or keeping your lights on.
Put another way:
  • We waste 650% more energy than all of our nuclear power plants produce
  • We waste 280% more energy than we produce by coal
  • We waste 235% more energy than we produce by natural gas (using deadly fracking)
  • We waste 150% more energy than we generate with other petroleum products
The Department of Energy notes:
Only about 15% of the energy from the fuel you put in your tank gets used to move your car down the road or run useful accessories, such as air conditioning. The rest of the energy is lost to engine and driveline inefficiencies and idling. Therefore, the potential to improve fuel efficiency with advanced technologies is enormous.

According to the DOE, California lost 6.8% of the total amount of electricity used in the state in 2008 through transmission line inefficiencies and losses.

Energy usage in the U.S. residential sector in 2006. The National Academies Press notes:

By the time energy is delivered to us in a usable form, it has typically undergone several conversions. Every time energy changes forms, some portion is “lost.” It doesn't disappear, of course. In nature, energy is always conserved. That is, there is exactly as much of it around after something happens as there was before. But with each change, some amount of the original energy turns into forms we don't want or can't use, typically as so-called waste heat that is so diffuse it can't be captured.

Reducing the amount lost – also known as increasing efficiency – is as important to our energy future as finding new sources because gigantic amounts of energy are lost every minute of every day in conversions. Electricity is a good example. By the time the energy content of electric power reaches the end user, it has taken many forms. Most commonly, the process begins when coal is burned in a power station. The chemical energy stored in the coal is liberated in combustion, generating heat that is used to produce steam. The steam turns a turbine, and that mechanical energy is used to turn a generator to produce the electricity.

Example of energy lost during conversion and transmission. In the process, the original energy has taken on a series of four different identities and experienced four conversion losses. A typical coal-fired electrical plant might be 38% efficient, so a little more than one-third of the chemical energy content of the fuel is ultimately converted to usable electricity. In other words, as much as 62% of the original energy fails to find its way to the electrical grid. Once electricity leaves the plant, further losses occur during delivery. Finally, it reaches an incandescent lightbulb where it heats a thin wire filament until the metal glows, wasting still more energy as heat. The resulting light contains only about 2% of the energy content of the coal used to produce it. Swap that bulb for a compact fluorescent and the efficiency rises to around 5% – better, but still a small fraction of the original.

Example of energy lost during conversion and transmission. Imagine that the coal needed to illuminate an incandescent light bulb contains 100 units of energy when it enters the power plant. Only two units of that energy eventually light the bulb. The remaining 98 units are lost along the way, primarily as heat.

Read more from "It's Not Just Alternative Energy Versus Fossil Fuels or Nuclear - Energy Has to Become DECENTRALIZED"