Electricity in the air: how ambient energy can ease consumption concerns

The world currently uses 607 quintillion joules of energy per year. By 2040, this figure will have increased to 777 quintillion joules. Both are staggering figures, but ones that are hardly surprising considering some economies are still developing and others seem hell-bent on rampant consumerism. With environmental concerns mounting and fossil fuel reserves on the wane, meeting energy demands will become one of the most significant challenges of the next few decades.

The key to overcoming this challenge may lie all around us: radio waves, Wi-Fi signals, kinetic energy and solar power are just a few examples of the types of energy that are being generated in vast quantities on an almost constant basis. These power sources, which are already present within a given system, are collectively known as ‘ambient energy’ and, despite their ubiquity, are going largely untapped.

Although plentiful, the majority of ambient energy is currently being wasted; lost as heat, light or other impractical forms. If the ambient energy that surrounds us can be collected and converted into electricity, then a solution to our energy needs, even if only a partial one, could be found. With our thirst for consumer goods showing no end and the Internet of Things (IoT) promising to deliver a host of new low-power sensors, our need for ambient energy appears greater than ever.

Starting small
While global annual revenues from energy harvesting systems are set to reach a value of almost $375m by 2020, the technology can hardly be described as mature. The energy levels being demanded by consumer electronics mean it remains difficult for ambient energy to compete with the robust infrastructure of well-established national electricity grids. This is also why we are seeing a decrease in battery life, despite the technology’s overall improvement.

“Single energy form harvesters cannot typically satisfy the needs of 24/7 operability, thus a combination of multiple forms of harvested energy is required for the majority of practical devices,” noted Manos Tentzeris, a professor of electrical and computer engineering at Georgia Tech. “The number of companies currently offering harvesting products remains small, but it is growing.”

Battery firms need not fear ambient energy… It could be used to augment their existing offering

A major stumbling block to the development of the ambient energy market is the requirement for energy to be generated locally. While existing companies like Wi-Charge and WiTricity – which use infrared light and magnetic resonance, respectively – are able to charge devices wirelessly, they require the installation of a powered energy transmitter.

Conversely, true ambient energy emerges when forms of energy are already present in the environment, such as solar power or Wi-Fi signals. Although commercial activity remains limited, Joshua R Smith, Associate Professor of Computer Science and Electrical Engineering at the University of Washington, believes genuine examples of ambient energy harvesters are beginning to be developed.

“I think the technology is just at the cusp of practicality,” Smith said. “There are a lot of potential applications that could create totally new market categories or products. For example, if it’s possible to build sensors into walls, roofs, roads or other places where batteries or wires are not practical, then it potentially becomes possible to do things that you would not even think of doing today.”

The energy harvesting market is expected to expand rapidly in the next few years. In the near future, an increasing number of products will need to be autonomous, miniaturised and easily scalable – pushing manufacturers towards ambient energy. Already, companies like EnOcean in Germany and Mide Technology in the US are developing ways to invigorate the market by taking the energy around us and making it usable.

Crossed wires
One of the major driving forces behind the growth of ambient energy technology is the increasing efficiency of consumer devices. “Since around 1945, the energy efficiency of electronics has been improving exponentially,” Smith said. “Computers today are more than a trillion times more energy efficient than their early ancestors. As energy efficiency continues to improve, the amount of workable applications will grow dramatically.”

In fact, this is already starting to bear fruit: Smith’s team at the University of Washington has begun to develop a battery-free, wireless mobile phone that operates exclusively by harvesting radio and light signals. Part of the team’s success stems from developments in ambient sensors, but energy efficiency also plays a huge part. The telephone is capable of operating from just 3.5 microwatts of power and, despite its limitations, can be used to make and receive calls, as well as connect to Skype.

Smith recognises that the potential for battery-free technology extends far beyond telecommunications: “When you are using low-end devices, batteries can represent a significant fraction of the cost. There are a lot of high-volume things that today are not electronic at all, but you could potentially give some smarts to them if you didn’t have to pay for a battery.”

With IoT and ambient energy working in tandem, sensors could be embedded into homes, offices and public infrastructure, with zero cost to power or maintain them. The IoT sensor market is expected to reach $38.4bn by 2022, but practical questions remain about powering the expected influx of new gadgets. Ambient energy promises a greener solution to this problem, reducing waste and creating a more energy efficient environment.

Taking charge
Perhaps the biggest challenge facing the ambient energy market is one of simple economics. With energy already so prevalent, it seems difficult to imagine a world where harvesting solar, Wi-Fi or kinetic energy actually makes much money.

One potential way of monetising this energy source is for existing players to get on board now. Battery firms need not fear ambient energy when it could be used to augment their existing offering. “Modules requiring continuous operability, such as wireless pacemakers, could utilise ambient energy harvesters for quick and continuous battery recharging or as a complementary emergency power source,” Tentzeris explained.

Traditional power companies could likewise embrace ambient energy as a new revenue stream. Smith has found Wi-Fi traffic sometimes requires a boost in order to power consumer electronics, so an online provider could simply deliver an enhanced wireless signal in exchange for an increased fee. Hardware firms also have a chance to grow their profits by including energy sensors or emitters. As such, market opportunities are present, but there could be a battle between well-established power firms and innovative start-ups to make the most of them.

“If you think about your own smartphone, there’s already an existing market case present,” Smith said. “You are probably always going to want a battery in your smartphone, but at the same time you may want the phone to still be usable in some way even if you have no battery. If you have a flat tyre or want to call for help, you don’t need all the power of a smartphone, you just need to be able to call or text somebody.”

If growing energy consumption offers cause for concern, then improvements to energy efficiency provide plenty of reasons for optimism. The latter is already ensuring ambient energy has more applications than ever before. With further research, this technological phenomenon promises a future free from the tethers of batteries and wires. The power is already out there; it simply needs to be put to good use.