What do typhoons, snow and human footsteps have in common?
They can all be harnessed to meet humanity’s growing energy needs. All it takes is a little lateral thinking.
Residents of the Okinawan city of Nanjo were on high alert when Typhoon Malou, the season’s 13th typhoon, struck on Sept. 6 last year. Atsushi Shimizu, however, could barely contain his excitement. “All right! Keep it up, keep it up!” he yelled. Shimizu, the president of Tokyo-based startup Challenergy, was watching the prototype of a new wind turbine rotate in the heavy winds.
“We’ll bring innovation to power generation,” Shimizu said. And indeed, the feat he is attempting — using the strong winds of typhoons to drive a generator — is a challenge no one has yet conquered.
Though it relies on wind, Shimizu’s turbine does not have propeller blades. Instead, it has three cylinders, each 3 meters tall and 50cm in diameter, that rotate to generate electricity. The turbine’s generating capacity of 1kW is enough to meet half of the electricity needs of a household.
Typhoons are a massive headache for the wind power industry because conventional turbines are not able to handle the enormous amounts of wind energy such storms produce.
To remedy this, Shimizu focused on a phenomenon called the Magnus force. When a ball or cylinder rotates in a strong wind, it produces a difference in wind speed between the right and left sides of the object. This difference causes the object to move in a curved path. “The Magnus force also works on curve balls,” Shimizu explained.
The Challenergy turbine comprises three cylinders attached to one rotating base. First, electricity is used to set the three cylinders spinning in the wind. Then the Magnus force takes effect, causing the base that supports the three cylinders to rotate. A generator beneath the base uses this rotation to produce electricity.
Challenergy wants to take typhoon-driven power generation beyond Japan. The company sees large markets in Vietnam, Taiwan and the Philippines, which are frequently hit by such storms. “We want to change hazard maps of the world to energy maps,” Shimizu said.
Typhoons are a potentially invaluable resource. A large storm can produce a level of wind energy equivalent to half the worldwide electrical generating capacity, according to the National Oceanic and Atmospheric Administration of the U.S.
Snow and storms are some of the radical new answers to our electricity needs
In Bibai, Hokkaido, a snowplow heads toward a huge warehouse, its engine droning and snow particles flying about. The warehouse, Yukigura Kobo, is used by JA Bibai, an agricultural cooperative, to store brown rice. Each year in mid-March, about 3,600 tons of snow — enough to fill 18,000 drums — is put into the storage facility and remains there through the summer.
The snow, piled nearly 10 meters high and almost reaching the ceiling, helps keep the inside temperature at 5 C and humidity at 70% during the summer. This provides the optimal environment for keeping the rice dormant and fresh.
The snow-cooled warehouse consists of a storage room for brown rice and a storage room for snow. In the rice storage room, heat is generated as the rice “breathes,” gradually raising the temperature in the upper part of the room to about 6 C. A blower sends this warmed air to the snow storage room, where it is cooled to near 0 C as it passes over the accumulated snow. The cooled air, which is too cold for the rice, is mixed with warm air and returned to the rice storage room.
“The annual electricity cost for the snow-cooled facility is about 4 million yen ($34,800) lower than for a facility using mechanical refrigeration,” said Yoshiyuki Tsujiwaki, a senior official at JA Bibai. The facility began operating in 2000. Today, about 50% of the rice handled by the agricultural cooperative is stored there and sold under the Yukigura Kobo brand.
People themselves can also be a source of energy.
“This system generates electricity by using vibrations transmitted to elements,” Kohei Hayamizu said, explaining how a small, light-up device works. Hayamizu is president of Soundpower, a startup in Fujisawa, Kanagawa Prefecture. The company’s vibration-based technology has enabled it to develop a power-generating floor that converts people’s footsteps into electricity.
The power-generating floor includes a layer of special materials called piezoelectric elements. When a person walks on the floor, say, in a corridor, the pressure disrupts the internal electrical balance of the piezoelectric elements. This creates voltage, generating electricity.
Piezoelectric elements are used in disposable cigarette lighters to produce electric sparks to ignite the flame. Soundpower improved the efficiency of these elements by changing their structure, and patented the new and improved version. The company also developed a circuit that features a smaller loss of electricity flowing through it. A person weighing 60kg and walking over the power-generating floor at a pace of two steps per second would produce an average of about 2 milliwatts of power.
In the future, Hayamizu aims to introduce his company’s technology into bridges and other infrastructure. He envisions it being used to provide a power source for smart sensors that can, for example, detect structural strain.
As bridges are constantly subjected to vibrations from cars and winds, they provide good power-generating environments, and using vibration-powered sensors would obviate the need to replace batteries in hard-to-reach places. Soundpower is already in negotiations with a general contractor for such a use.
Toto, meanwhile, has come up with a unique remote control for its Washlet series of toilet seats.
The eco-friendly control panel, developed jointly with Mitsumi Electric, does not use a battery. Instead, it has a generator inside. When one of the remote’s functional buttons is pressed, the resulting force rotates a magnet in the coil of the generator. Electricity thus generated by electromagnetic induction is used to transmit signals to the Washlet seat.
The electrical energy generated by one push of a button is only about 1,000 microjoules, but it is very effective. And since the toilet seat is operated via remote control, there is no need for wiring behind the wall. “The remote control can be used without the trouble of replacing a battery,” said its developer, Satoko Morioka of Toto’s electronic engineering division. “The product has proved popular with the owners of facilities where it has been installed,” she said.