An image of Abu Dhabi's Masdar Tower, which will be the world's first large-scale building to produce more energy than it consumes. / Courtesy of Masdar Project

Scientists Give Second Thoughts to Overlooked Motions in Everyday Life

By Cho Jin-seo
Staff Reporter

Energy prices continue to rise due to the ever-increasing demand for fuel and their limited reserves. Concerns over the global warming phenomenon also make governments around the world levy heavier taxes on its consumption. Korea is no exception in the energy crisis, and people are beginning to look into securing cheaper and sustainable sources.

The government is giving out subsidies to encourage the supply of renewable, eco-friendly energy such as wind power and solar power. But at the same time, scientists and engineers are paying attention to recycling existing energy that have been ignored in people's everyday activities.

Like machines burn fuel, people burn food for physical or chemical actions. In the process, a lot of energy is wasted in the form of heat, light, or sound. For example, automobiles can harness only around 15 percent of the power from the fuel, and even that gets lost when the car decelerates.

The hybrid car, such as the Toyota Prius, is one example of a system that attempts to raise the car's fuel efficiency by recapturing the energy wasted during braking. Hybrid cars use a system known as regenerative braking. When a driver steps on the brakes, a generator converts the kinetic energy of the car into electrical energy and stores it in a battery. In ordinary cars, the kinetic energy is lost through heat and sound caused by the friction in the brake pad and the tire surface.

The concept of the hybrid engine is being adopted in elevators, too. Last week, Otis Elevator showed a regeneration system for elevators it developed from 2003 to 2006 in its Korean laboratory.

An elevator car is linked to a counterweight via a pulley system. When an ascending car is full of passengers, the system uses electricity to run a motor that pulls up the car. When the car is full on the way down, it needs energy to break so it does not free fall. Otis' regenerative drive collects energy when a fully loaded elevator is descending or a lightly loaded car is ascending, just like the Hybrid car recharges its battery from braking.

The electricity is then returned to the building's power grid to be reused for such things as lighting and heating. Otis says the recycling system can reduce the overall elevator energy usage by up to 75 percent compared to systems with non-regenerative drives, lowering overall building operating costs and delivering significant annual savings to building owners and tenants. When applied to all of the 340,000 elevators operating in Korea, that can save 1.7 billion kilowatt hours of electricity, or 200 billion won. The saving is also equivalent to 10 million barrels of gas and 260,000 tons of carbon dioxide emissions, the firm says.

In a bolder attempt, engineers are applying the regeneration system to human actions. Earlier this month, researchers at a Canadian venture firm Bionic Power showed a man-power generator called Biomechanical Energy Harvester.

The device, which resembles an orthopedic knee brace, can generate up to five watts of power without any discomfort to the wearer. For example, for every minute of walking, the device can generate enough power for 10 minutes of talk time on a typical mobile phone, the firm says.

The innovative part of the device is that it can actually make walking more comfortable and less tiring for the wearer of the device. People walk by moving each leg forwards and backwards. The device operates during the end of the moving phase of each leg, which is similar to the braking phase of an automobile or an elevator. Thus, it helps to decelerate and simultaneously produces electrical power.

``Our technology is really about freedom,'' says Yad Garcha, CEO of Bionic Power. He said the device can be especially helpful for the military. ``The Energy Harvester not only lightens a soldier's load, allowing him to travel farther and faster, but it could radically reduce shipping and logistics costs.''

On a larger scale, in Abu Dhabi, the United Arab Emirates, designers and engineers are posed to build the world's first large-scale ``positive energy'' building, which will produce more energy than it consumes.

The $300 million building will be used as the centerpiece of Abu Dhabi's $22 billion development project of the world's first zero-carbon, zero-waste, car-free city. The design features one of the world's largest building-integrated photovoltaic arrays and employs the largest solar thermal driven cooling and dehumidification system. Compared with typical mixed-use buildings of the same size, the Headquarters will consume 70 percent less water.

In Korea, Busan has started an energy recycling business, selling the heat produced from garbage incinerators to nearby factories.

The city began to supply the steam produced at Myeongji Resource Recovery Facility to Renault Samsung Motors and Samsung Electro-Mechanics at 11,500 won per ton.

The facility has produced some 200,000 gigacalories of heat every year, and only 35 percent of it was used in heating the water for nearby towns. The city government expects that the sales of the remaining steam to factories can earn it 900 million won per year.

indizio@koreatimes.co.kr