A hula hoop that can charge mobile phones and a flytrap that uses three-day-old shrimp are among the inventions Thai youths have won awards for.

Five teams of talented Thai students took out gold awards at the International Exhibition for Young Inventors (IEYI) 2012, an annual international event that was this year held in Bangkok.

The winning teams created inventions that tackle contemporary lifestyle issues including energy, disturbing insects and agriculture.

One of the most interesting employed a hula hoop to charge mobile phone batteries. The brainchild of Apisit Wannarancsri and Jukkit Buppha from Samutsakhon Wittayalai School, the hula hoop battery charger was inspired by two familiar scenes they see every day _ people playing with hula hoops and people using mobile phones. Electricity is generated when 12 magnets in the hula hoop react with copper wire which has been wrapped in fabric and sewn into in a belt. The circuit is created by the belt and the electric current is transformed from alternating current (AC) to direct current (DC), which can be used to power a mobile phone.

"Besides exercising, this can also help reduce global warming, the telephone charger can be used in daily life, but further development will make the device more interesting, such as lighter weight," Jukkit said.

Another example of environmentally conscious invention is "Green Products" from Hat Yai Wittayalai 2 School. Created by Varunyou Dropphupha and Kannika Chaisiri, Green Products is a flytrap that uses a three-day-old shrimp as bait. The shrimp at three days old has a distinctive smell that lures the insects.

Designed with a conical shape, the top of which contains water, the flies that flock into the device will automatically fall into the liquid. A CD is also used to prevent flies from escaping.

The team pointed out that the CD accelerates the flies' death rate. The life cycle of flies is normally four to five days, but the device will ensure all will die within 12 hours.

"When you leave the device for three hours, a thousand flies will be trapped," the inventors claim.

Artit Attaporn and Weerachai Sampao from Klongtomratrangsan School, Krabi, invented the "3in1 power generator" to reduce the use of natural resources and lower fossil fuel consumption.

The device uses turbines and solar panels which are conductors for wind and solar energy.

The machine has a clutch that regulates the spinning of the motor blades while the dynamo functions as a power generator using the wind turbines. The power generator has a universal joint to adjust the angle of rotation.

Weerachai explained that the 3in1 power generator had blades spinning in water to manage waste water, and said they could also generate electricity when there was no wind through an electric motor bound to the propeller.

The 3in1 power generator has a system to convert the direct current (DC) into alternating current (AC) from the battery. The conversion from 12 volt DC to 220 volt AC makes it useful in buildings, shrimp ponds and fish ponds. The wind turbine blades, meanwhile, produce power that can be used for water treatment.

"This is a prototype of combined power generator and water treatment by using renewable and alternative energy. The machine also helps reduce global warming," Weerachai said.

Aside from green technology, inventors also tackled the subject of hometown lifestyles. The team of students from Suratpittaya School opted to deal with "stink beans", or Sa-Tor, a kind of crop grown in Thailand's south. It is an economic crop for planters and a popular crop for people in the south.

The team members, Nattapong Chinnara and Nantakan Longlod, invented a stink bean flower pollinating device to improve yields. With its flowers generally blooming at night, the method of the stink bean's fertilisation requires cross-pollination because stamen and pistil bloom at different times.

Cave nectar bats account for 80% of pollination, while the rest is provided by insects. But the number of pollinating animals is declining in nature, resulting in fewer stink bean pods and the need for a pollinating device.

The device is comprised of three parts. The first collects pollen grain and is made from a brush connected with a towline. The pollen grain will be brushed into storage by pulling the towline. The second part is a pollination agent which is made from a smooth-surface cloth that covers the plate like the bat's hairy chest.

"When we push the device, this cloth will touch the stink bean's pistil and causes fertilisation," the inventors said.

The third part is LEDs for illumination because the pollination occurs at night.

Nattapong said after using the device for stink bean pods, successful fertilisation was 35% higher than the natural process, proving its efficiency for stink bean pollination.

It costs only 750 baht each and should excite planters as they can increase the stink bean productivity.

Nutthawut Boonrueng and Natipong Yaphasert, from San Kamphaeng School, Chiang Mai, created the "Water garbage collector using solar energy" project.

They built a garbage collector in the shape of a tiny boat so that it can operate in water. A 12-volt battery charged from solar cells is used as power resource.

The battery supplies power to two destinations: the motor that drives the collector boat, and the motor that steers the collector belt.

The motors are attached to the wheels. There are 12 wheels altogether: six for the collector boat and six for collector belt. The driving boat motors work with rotors to propel the collector forward and backward. The inventors use a remote control, which they took from a radio controlled toy, to manipulate the direction of machine.

"We can control the garbage collector to go straight, turn right or turn left, within the maximum range of 20m," said Nutthawut, noting that the machine can load up to 3kg of garbage.

The machine helps reduce conventional energy consumption while also increasing oxygen in the water with its rotors.

However, the boat's limitations include not being strong enough to perform in fast water or during the rain because the motor can be damaged.

Other than the five teams to win gold, there were another seven Thai teams who won the silver, and 18 teams went home with bronze awards.

Teams from Hong Kong, Indonesia, Japan, the Philippines, Malaysia, Singapore, Taiwan, Thailand and Vietnam participated in the event. Malaysia was ranked the top country after achieving seven gold awards.

The talent and inventiveness of those Thai youth will only pay off in future if there is continuous support and coaching for further development.