David Grice, ZMDI
Almost 50 years before Einstein’s famous gendakenexperiments, Scottish physicist James Maxwell published his own intriguing thought experiment to challenge the inviolability of the Second Law of Thermodynamics. In Maxwell’s proposed challenge to this law, he imagined a microscopic, intelligent creature that could open and close a small trap door between two chambers of a gas-filled container. If this tiny creature, who came to be known as Maxwell’s Demon, could manipulate the trap door so that more gas molecules with higher velocity were captured in one of the chambers, the temperature of that chamber would increase spontaneously, thus violating the Second Law. This marvelously simple puzzle challenged scientists for the next 100 years as they endeavored to prove rigorously why such a creature, or its mechanical analog, could never succeed.
Even though it is universally accepted that the ideal can’t be realized, engineers are working hard to create something as close as possible to Maxwell’s mythical creature. Although it goes by a less sinister name, the technology of micro power energy harvesting uses intelligent and efficient means to extract the maximum available power from a wide variety of background energy sources, including thermal, acoustical, light, radio frequency radiation, and even plants. The combination of innovative new harvesting devices, ultra-low power management, signal conditioning, and computing circuitry, and the ever-increasing demand for remote sensing and control is creating an explosion of new applications and gadgets that take advantage of energy harvesting. Another important contributing factor to this rapid expansion is the emergence of standards like the EnOcean wireless standard. These standards provide interoperability between devices, accelerating the acceptance and deployment of energy harvesting technology.
Systems using remote sensors that are powered by background energy are enabling a multitude of innovative ways to improve performance while reducing cost and energy consumption. For example, a “smart” building equipped with such sensors to monitor temperature, humidity, occupancy, illumination levels, etc., can optimize the performance of the HVAC, lighting, and security systems with significant cost savings because energy is applied only when and where necessary. Installing Building Automation Systems (BAS) with these features can reduce energy consumption by an average of 40%, but the investment and infrastructure required to implement traditional wired sensor nodes has been prohibitive. Those barriers are reduced significantly with self-powered, wireless sensors that comply with “plug and play” standards.
Energy harvesting has been around for a very long time, as ancient windmills and waterwheels can attest. However, new technologies like MEMS and ultra-low power electronic circuitry are enabling a whole new class of micro power harvesting machines. These innovations, coupled with greater energy demand and awareness, are fueling a renaissance in energy harvesting technology. What will be the impact on buildings, automobiles, supermarkets, clothing, and even our bodies in the future? If Maxwell’s Demon represents the ideal in energy harvesting, how close can we come to achieving it? What role, if any, does artificial intelligence play in implementing such a creature or machine?
