Moving water can now be converted to stored energy thanks to a product named Estream introduced by Enomad Corp. The product, which can fit into your backpack, can charge every usb-connected mobile devices even while users are off-grid.

According to Enomad Corp, the portable water generator weighs round 800 grams, or 1.8 pounds. To store energy, users should remove the cover, unfold the turbines and place Estream in running water. The portable generator will start to automatically generate electricity and recharge its  battery.

“As a generator, it produces 2.5W – 7W of energy,” the company says. “As Estream is suspended in water, water flow rotates the turbine. The rotation enables the generator to generate electricity. Estream works well even in a weak current or behind your kayak.”

“It takes about 4.5 hours to fully charge 6,400 mAh built-in battery by running water. Once fully charges, the battery can charge up to 3 smartphones, GoPros or even tablet PCs, twice as fast as a regular outlet,” the company adds. “It is rechargeable, so as long as you you have access to running water, you can continue to charge your devices – even on the longest adventures.”

US-based company Kogalla came up with a similar concept that with a product that harvests sun light and allows you to charge your phone and other fast-charging devices.