This small power plant weighs less than a pound and features a hydrodynamic turbine that attaches to a 70-inch long rope-like drive shaft. Secure the donut-shaped device around a stick jammed in the ground, drop the turbine in water — even shallow — and Blue Freedom’s 5W generator will fully top off the built-in 5,000mAh battery within a couple of hours. Then, it’ll charge any and all of your USB-compatible devices at up to 2A speeds.