Farmers will soon be tapping into 鈥渃ow power鈥� to help them water their crops. Gary Henderson of Gravitational Systems in New York has developed a pump that鈥檚 driven by cows walking over it. The pump has a horizontal metal plate that can be embedded in the ground along any path the cows use regularly. When a cow steps onto the plate, it compresses a water-filled plastic bladder underneath. This pushes water out through a one-way valve into a pipe. As the beast steps off the plate, springs inside the bladder force it to expand, drawing water in through another one-way valve.
The pumps could be installed in rows to force irrigation water from rivers or lakes into a water tower. They could also be put in roads to generate electricity as cars drive over them, says Henderson. Water forced out of the pump turns a generator before returning to the pump. 鈥淵ou can imagine having these in cities like Los Angeles, with the cars driving the pumps and the pumps powering roadside lighting and signs,鈥� he says.