Ocean Renewable Power Company (ORPC) is installing the largest tidal power plant to date in U.S. waters. The Maine-based energy company is using the movement of tides to generate renewable power for the U.S. Coast Guard station in Eastport, Maine. The bay's five-knot tides provide a predictable, clean source of energy.
While tidal water moves more slowly than wind, it provides more force. Tide velocities peak four times a day, and one of ORPC’s innovations is developing the systems to harness that power as the turbine spins at different rates. The power plant will use advanced cross-flow turbines, a permanent magnet generator and a power electric system that transforms the generator’s energy output to grid-suitable electricity.
The barge-based plant uses the power from two turbines to charge large battery packs, which are ferried daily by skiff to the Coast Guard station in Eastport. The battery packs provide roughly 20 kilowatt-hours of power daily, about half of the energy needs of the 41-foot search and rescue boat docked there.
This plant is a small power plant, as it would take 25 such turbines to equal the rated capacity of one average wind turbine.
This “demonstration” project cost $4 million, including more than a million dollars of federal and state support. ORPC is using the data it is gathering to fine-tune a larger installation in Cobscook Bay, planned for 2011. That system, according to the company, should generate enough electricity to power 50 or 60 homes.
Thursday, August 26, 2010
Sunday, August 08, 2010
A case in point may be Mansukhbhai Prajapati, a craftsman based in Gujarat. Prajapati, a high school dropout, has been called a 'true scientist'. His Mitti Cool, a clay refrigerator that works without electricity, has turned the world's attention to simple steps in sustainability.
Presenting the national award to Mansukhbhai in 2009, India’s President Pratibha Patil appreciated his work and asked him for a Mitti Cool. Scientists and journalists from across the world have visited his unit to see how he makes eco-friendly products at a low cost. The simple and unassuming Mansukhbhai has been modestly successful financially, but his ambition is to make more low-cost and eco-friendly products for the masses.
"A good majority of Indians cannot buy a fridge as it is expensive. Besides this, electricity bills and maintenance costs are also high. Mitti Cool is an eco-friendly product which has no maintenance costs. It also retains the original taste of vegetables, says Mansukhbhai who has sold 1500 units so far.
Prajapati’s refrigerator cools naturally without using any electricity. It is ideal for rural areas with an erratic power supply. They are priced from Rs 2,000 (USD 44). The refrigerator has a capacity of 50 liters and its upper portion stores about 20 liters of water, while the section below the water tank has separate space to store fruits, vegetables and milk. The water in the tank keeps the temperature lower in the cabinet so that vegetables and fruits stay fresh for almost five days, while milk can be preserved for three days.
Armed with the success of the Mitti Cool refrigerator, Mansukhlal started experimenting with non-stick tawas (fry pans) and water coolers. For example, the clay water cooler comes with a 0.9 micron candle inside the water storage pot to filter water. Clay is a magical ingredient, Mansukhlal believes, because it's environment-friendly, and also because these natural products don't need electricity to function.
The hottest selling item today from Mansukhlal's Mitti Cool range is the non-stick tawa, which is substantially cheaper than other non-stick utensils. It is again made out of clay and has a Teflon coating, which seeps into the pores of the clay so that it cannot flake off during cooking. Unlike other non-stick cookware available in the Indian market, this one is priced affordably at Rs 50 (USD 1).
And of course simple clay is the very essence of sustainable materials.
Posted by Richard Wottrich at 6:58 AM