Last year a large wind farm went up on an island near Kingston, Ontario, where I live. The installation consists of 86 turbines scattered around the island, dozens of which are visible from the city’s waterfront. The decision to build the farm was controversial. Although everyone likes the idea of clean renewable energy, many people feared the impact of the farm on the natural landscape, human health and wildlife habitat. Kingston sits astride a major North American migration route and some residents expressed concerns that untold numbers of migrating birds, as well as local bats and birds, would perish on the rotating blades. This has been a problem for wind farms all over the world.
One Californian inventor has come up with a uniquely novel solution: airbags for birds. In May 2008, John Silwa of Los Altos Hills filed an application for a "Method and Apparatus for Reducing Bird and Fish Injuries and Deaths at Wind and Water-Turbine Power-Generation Sites” (US 2008/0298962). The invention consists of airbags installed on turbine blades that would be activated by a motion-sensing or proximity sensing system. In theory, birds approaching the blades would trigger the airbags and bounce off unharmed or with “temporary stunning, blackout or non-critical injury.” It’s hard to believe that an airbag mounted on a spinning turbine weighing several tons would save a tiny bird.
Other inventors have taken more conventional approaches. Dr. William Hodos, professor emeritus of psychology at the University of Maryland, patented a system of painted patterns on turbine blades that make them more visible to birds (US 6,623,243). Melvin Kreithen of the University of Pittsburgh proposed using pulses of microwave energy to scare birds away from turbines and other structures (US 5,774,088). A published application filed by Keith Lima of Massachusetts discloses a system of ultrasonic or sonic wave generators that would deter birds from flying into wind turbines (US 2005/0162978). Canadian Angus Tocher has patented a “habitat friendly” wind energy extraction system based on small turbines encased in shrouds (CA 2,501,025 and US 7,220,096). German inventor H. Schlueter proposes mounting an ultrasonic sound producing device on rotor blades to warn bats (DE 102007025314).
The interdisciplinary nature of this problem makes it an interesting patent search challenge. The obvious starting point would be IPC class F03D, which covers wind motors and turbines. One possible search strategy is:
IPC = F03D AND Title/Abstract Keyword = (birds or bats or animals or fowl)
Other appropriate IPC codes include A01M29, which covers devices for scaring animals and birds, and H04B1 for electric signaling systems and G08B3 for audible signaling devices that could be used to frighten or warn animals.