Power/Performance Bits: May 27

Battery captures waste heat, converts it to electricity
While vast amounts of excess heat are generated by industrial processes and by electric power plants, researchers around the world have spent decades looking for ways to harness some of this wasted energy, according to engineering researchers at Stanford and MIT. They pointed out that most of these efforts have focused on thermoelectric devices, which are solid-state materials that can produce electricity from a temperature gradient, but that the efficiency of these types of devices is limited by the availability of materials.

Now the researchers report they have found a new alternative for low-temperature waste-heat conversion into electricity, that is, in cases where temperature differences are less than 100 degrees Celsius.

Nearly all power plants and manufacturing processes, like steelmaking and refining, release tremendous amounts of low-grade heat to ambient temperatures, and the new battery from the team is designed to take advantage of this temperature gradient at the industrial scale.

Stanford and MIT researchers have developed a four-stage process that uses waste heat to charge a battery. First, an uncharged battery is heated by waste heat. Then, while the battery is still warm, a voltage is applied. When fully charged, the battery is allowed to cool, which increases the voltage. Once the battery has cooled, it actually delivers more electricity than was used to charge it. (Source: Stanford and MIT)

Based on the thermogalvanic principle, which states that the voltage of a rechargeable battery is dependent on temperature, the system subjects a battery to a four-step process: heating up, charging, cooling down and discharging in order to harvest thermal energy.

GPUs improve cancer patient care
Medical physicists at UT Southwestern Medical Center are finding new ways to use the speed of video game processors to promote research that is aimed at improving patient care.

In recent years, video game processors – GPUs — have become massively powerful as game makers support increasingly elaborate video graphics…and medical experts have taken note of the GPU’s rapid-fire processing. Among the pioneers looking for ways to apply the processing speed of GPUs to medical use is Dr. Steve Jiang, director of the division of medical physics and engineering, and professor and vice chairman of radiation oncology at UT Southwestern.

One practical application is reducing the time required to calculate the radiation dose delivered to a tumor during proton radiotherapy, he said. The faster video processors can reduce the time of the most complex calculation method from 70 hours to just 10 seconds, which is an astonishing improvement in processing speed.

The popularity of video games has resulted in a tool that is very beneficial for scientific computing in medicine, Jiang said in a statement from the university. The quicker results mean increased convenience for patients and physicians, and translate in a significant way to better patient care.

Radiotherapy is often delivered in many treatments that can span weeks, during which time the patient’s anatomy or the tumor itself can change. Dr. Jiang’s highly efficient calculation allows for more accurate treatment plans based on daily calculations that are adapted to changes in the patient’s daily geometry (such as weight, size and shape of the tumor), as well as the healthy tissue around the tumor. With the faster processor, doctors can make calculations before each treatment, instead of re-using older data, and new calculations can make the treatments more exact, sparing surrounding healthy tissue.

Although video games may seem to offer little beyond entertainment, the consumer demand was so intense that game developers created better, faster, and cheaper processors for video games than for any other applications and market forces are strong and act much quicker than federal or state research funding mechanisms.