Shedding Light on Energy: Energy Efficiency

This entry in the Shedding Light on Energy series explores how scientists and engineers have increased the efficiency of energy sources to produce more energy at lower cost. Energy efficiency is a measure of useful output compared to the amount of energy input. The first lesson covers improvement in efficiency for light bulbs. While the incandescent bulb has delivered light for over 100 years, only a small percent of the electrical energy is actually transformed into light; the remaining energy is lost to heat. Newer LED bulbs are much more efficient, generating greater light with far less heat emitted. Turning to chemical energy, the narrator points out that gas-powered cars are only 25% efficient in utilizing fuel while the remaining energy is expended as heat through exhaust or used by the brakes. Walking is technically more efficient than running in terms of energy conversion and biking beats both since less effort is required to move the body. Dropping an inflated ball from various heights illustrates the power of gravitational pull to transform energy into kinetic energy, as the ball will bounce back up when it hits the surface but lose energy on each rebound. This concept is featured in prosthetic limbs that make use of the arch of the foot and tendon to capture and retain kinetic energy for the next step. A solid primer on various types of energy transformation that also explores the possibilities for future advances in energy efficiency, this is recommended. [Note: the other titles in the series are Forms of Energy and Measuring Energy.] Aud: J, H, P. (T. Root)