How Computer Processors Can Become a Million Times More Energy Efficient
People waste a lot of electricity powering the computers they have at home and work. Organizations throw away $4 billion a year powering PCs that aren’t being used and many people at home fail to take advantage of the simple power management features built into every computer that can help them reduce monthly electric bills.
But if a team of electrical engineers at the University of California, Berkeley, are right, worrying about saving energy with computers, at least when it comes to microprocessors, may become a thing of the past.
Professor of electrical engineering and computer sciences Jeffrey Bokor, along with electrical engineering and computer sciences graduate students Brian Lambson and David Carlton, are conducting research on magnetic computer microprocessors that, in the future, could use a million times less energy than today’s silicon chips.
In fact, the researchers claim that future magnetic microprocessors might be so energy efficient that they could consume the least amount of energy allowed by the laws of physics.
Nanomagnets Could Make Electrons in Microprocessors Virtually Obsolete
The silicon microprocessors of today rely on electric currents, or moving electrons, to carry out the functions of computers, which include memory, logic, and switching operations. The problem with moving electrons around is that it produces a lot of waste heat and requires lots of energy.
However, microprocessors that use very, very small magnets measured in nanometers’ would theoretically require no moving electrons. The magnet-powered microprocessors would use a staggeringly small amount of energy, only 18 multielectron volts of energy per operation at room temperature, which is the minimum allowed by the second law of thermodynamics and is called the Landauer limit.
The Landauer limit represents the minimum amount of energy that can be used for a single logical operation, the simplest and most basic function of a computer, such as determining an AND or OR output that produces the ones and zeros used in binary code. It takes modern silicon-based microprocessors a million times as much energy to complete the same single operation because of the electrical resistance involved in moving electrons.
“Today, computers run on electricity; by moving electrons around a circuit, you can process information,” Lambson said. “A magnetic computer, on the other hand, doesn’t involve any moving electrons. You store and process information using magnets, and if you make these magnets really small, you can basically pack them very close together so that they interact with one another. This is how we are able to do computations, have memory, and conduct all the functions of a computer.”
The Energy Efficiency Gains of Nanomagnets Could Be “Revolutionary”
The nanomagnets used by Bokor and his team to build magnetic memory and logic devices are about 100 nanometers wide and about 200 nanometers long. They have the same north-south polarity as bar magnets, which allows them to represent the ones and zeroes of binary code simply through their up-or-down orientation. When multiple nanomagnets are brought together, the interaction of north and south poles resembles transistor behavior and allows for simple logic operations.
But there are a few obstacles that need to be overcome if the technology is to reach its true energy efficiency potential.
Presently, electrical currents are used to generate a magnetic field and to flip the nanomagnets. Unfortunately, the electrical currents use a lot of energy and prevent the technology from reaching anywhere close to the Landauer limit. Cooling the nanomagnets will help, since the temperature is directly related to the Landauer limit, but the researchers hope that the nanomagnets can eventually be made with new materials yet to be developed that will make electric currents unnecessary, except maybe for relaying information from one microchip to another.
Additionally, when power consumption decreases, the nanomagnets become more susceptible to problems due to random fluctuations from thermal effects and “noise” such as stray electromagnetic fields. The result is that low energy and high performance are, for now, still at odds.
But even if research into nanomagnets gets close to the Landauer limit, all electronics, and not just computers, could become extraordinarily energy efficient.
Even if we could get within one order of magnitude, a factor of 10, of the Landauer limit, it would represent a huge reduction in energy consumption for electronics, Bokor said. It would be absolutely revolutionary.
Ultimate Energy Efficiency: Magnetic Microprocessors Could Use Million Times Less Energy Than Today’s Silicon Chips,ScienceDaily.com, July 5, 2011.