A Chinese technologist has invented and patented an irrigation device that consumes no energy.

Zhu Jun, inventor of the Puquan Pump, said Monday that his tiny pump irrigates plants automatically.

The invention works on the principle that water moves from a comparatively humid environment to a comparatively dry environment.

Zhu got the machine to pour water from an accessory storage bag to soil near plant roots.

The Beijing inventor used slow-releasing technology in the device, allowing the water bags to last for one to three months.

Each device costs less than one yuan (12 US cents) to produce. Zhu estimated that large-scale manufacturing could further curtail costs.

Traditional irrigation for 100 small trees might cost 570 yuan per year. The Puquan Pump, however, costs just 100 yuan each year and offers a survival rate of 95 percent, a report from an individual assessment agency said.

Shen Guofang, vice president of the Chinese Academy of Engineering and a silviculture expert, used the pump for irrigating his potted flowers. "It's a good energy-free and environment-friendly technology," Shen said.

Zhu has applied for a patent from the world Patent Cooperation Treaty (PCT), which ensures priority of patent applicants for applying for patent rights in developed countries.