Powering the Future

For years there have been predictions that the world would be filled with small sensors that would revolutionize the way we live. Five years ago, there were numerous predictions that we’d be living in a cloud of sensors. The limitation on realizing that vision has been figuring out how to power sensors and the other electronics. Traditional batteries are too expensive and have a limited life. As you might expect, scientists from around the world have been working on better power technologies.

Self-Charging Batteries. The California company NDB has developed a self-charging battery that could remain viable for up to 28,000 years. Each battery contains a small piece of recycled radioactive carbon-14 that comes from recycled nuclear fuel rods. As the isotope decays, the battery uses a heat sink of lab-created carbon-12 diamond which captures the energetic particles of decay while acting as a tough physical barrier to contain the radiation.

The battery consists of multiple layers of radioactive material and diamond and can be fashioned into any standard batter size like a AAA. The overall radiation level of the battery is low – at less than the natural radiation emitted by the human body. Each battery is effectively a small power generator in the shape of a traditional battery that never needs to be recharged. One of the most promising aspects of the technology is that nuclear power plants pay NDB to take the radioactive material.

Printed Flexible Batteries. Scientists at the University of California San Diego have been researching batteries that use silver-oxide zinc chemistry. They’ve been able to create a flexible device that offers 10-times the energy density of lithium-ion batteries. The flexible material means that batteries can be shaped to fit devices instead of devices designed to fit batteries.

Silver–zinc batteries have been around for many years, and the breakthrough is that the scientists found a way to screen print the battery material, meaning a battery can be placed onto almost any surface. The printing process paints in a vacuum and layers on the current collectors, zinc anode, the cathode, and separator layers to create a polymer film that is stable up to almost 400 degrees Fahrenheit. The net result is a battery with ten times the power output of a lithium-ion battery of the same size.

Anti-Lasers. Science teams from around the world have been working to create anti-lasers. A laser operates by beaming protons while an anti-laser sucks up photons from the environment. An anti-laser can be used in a laptop or cellphone to collect photons and use them to power the battery in the device.

The scientific name for the method being used is coherent perfect absorption (CPA). In practice, this requires one device that beams out a photon light beam and devices with CPA technology to absorb the beams. In the laboratory, scientists have been able to capture as much as 99.996% of the transmitted power, making this more energy-efficient than plugging a device into electric power. There are numerous possible uses for the technology, starting with the obvious ability to charge devices that aren’t plugged into electricity. But the CPA devices have other possible uses. For example, the devices are extremely sensitive to changes in photons in a room and could act as highly accurate motion sensors.

Battery-Free Sensors. In the most creative solution I’ve read about, MIT scientists started a new firm, Everactive, and have developed sensors that don’t require a battery or external power source. The key to the Everactive technology is the use of ultra-low power integrated circuits which are able to harvest energy from sources like low-light sources, background vibrations, or small temperature differentials.

Everactive is already deploying sensors in applications where it’s hard to change sensors, such as inside steam-generating equipment. The company also makes sensors that monitor rotating machinery and that are powered by the vibrations coming from the machinery. Everactive says its technology has a much lower lifetime cost than traditionally powered sensors when considering the equipment downtime and cost required to periodically replace batteries.