August 2009 Archives

Regular capacitors are just ok. Supercapacitors, though, will blow your mind.

Well, maybe not, but they do have a much higher energy density than regular old capacitors, like the ones that you can buy at Radio Shack. Not just a little bit more either, but they can hold up to thousands of times more energy than a typical electrolytic capacitor (the ones used in high-current and low-frequency electrical circuits like power-supply filters or in audio amplifiers).

The point is this: supercapacitors—or ultracapacitors—could be used in electric-gas hybrid cars to increase their efficiency, according to a study done at Argonne National Laboratory. Technology Review covered the story.

"Ultracaps" can cut down the size of a hybrid's battery, as well as increasing the lifespan. Not to mention the lower cost and associated drop in price (TR estimated "hundreds of dollars of net savings").

Chad Hall, COO of Ioxus, a company which manufactures ultracapacitors, points out that the function of ultracaps is a little different from the battery, adding, "If you need to start a motor, an ultracapacitor is a good way to do that," he said.

For oh so long, arguments against implementing renewable energy have focused on cost. Of course, the financial cost is only part of the picture—the other part being the immeasurable cost of long term damage to our environment if we don't change the way we consume energy.

Normal old coal is dirty and cheap. Clean coal is still kind of dirty, but really expensive. Photovoltaics, wind energy, geothermal plants, are pricey, but very clean. Even with arguments such as this, the reality is that renewable energy sources are expensive to implement. There is hope, however, for a competitive market. It seems that prices have declined fairly dramatically in the past six months. According to New Energy Finance, a London-based research firm:

The price for long-term silicon contracts has fallen about 50 percent this year from a year ago and come close to the spot market price of $67 per kilogram, or about $0.50 per watt.

click for larger image

image from Dominic's pics on flickr.com
under Creative Commons

Adding to that, there is the Wall Street Journal, who point out that selling prices for solar panels have come down about 40 percent in the last six months alone. These lower silicon costs will hopefully result in larger markets for solar panels.

Solar panels are a viable option for the production of sustainable energy, but we can't cover the planet in solar cells. People need space to walk, drive, and have picnics. So our resources need to be effectively and efficiently used—we can't just throw solar panels around willy–nilly. If the human race takes one lesson from the past, it should be: use your resources wisely.

Two recent papers, both published in the Journal of Renewable and Sustainable Energy, point out a couple of methods that may help us do just that.

The first is by Emanuele Calabrò from the University of Messina, Italy, and calculates—for different latitudes—the angle a solar panel should be pointed so that it collects the most sunlight. Calabrò states, "Solar radiation varies with geographic latitude, season, and time of day due to the various sun positions in the sky. Hence, the problem of designing the optimal tilt angle and the orientation of a solar panel arises for maximizing solar radiation collection at a fixed latitude."

The second study discusses an approach to estimate the solar resources available to an area without extensive measurements. Rajeev Aggarwal, from the Dr. Y.S. Parmar University of Horticulture and Forestry in India presents a novel set of measurements that do not rely on meteorological data, but instead are based on latitude, longitude, and altitude measurements. The simplified solar radiation calculation comes surprisingly close to past, more detailed, measurements, which took into account weather measurements taken over several years at a particular location. The result is that potential solar sites can be scouted out more efficiently.

These type of on-the-fly and accurate measurements become especially important in third world countries and rural areas. The papers may present small ideas, but they are crucial in increasing the overall performance of solar energy resources.