Ambient Energy—Untapped Power for the Future

By Rick Laezman*

Wireless communication and internet network devices that connect the modern city could be tapped for ambient energy. ©tawatchaiprakobkit

To prevent irreversible climate changes and sustainably power the future, a myriad of possible energy sources are being explored.

While renewable energy and electric cars grab many of the headlines about reducing carbon emissions, one of the most promising avenues is harnessing “ambient” energy from power-consuming devices themselves.

Many forms of ambient energy created by nature are already available for use by humans. In an environment driven by innovation and the determined pursuit of whatever can be done, it should come as no surprise that many efforts are underway to capture even more of this seemingly ubiquitous power source.

What is Ambient Energy?

The term ambient energy refers to energy that is available in the surrounding environment. This is a very broad definition and includes many different types of ambient energy.

To better understand the concept, this power source can be divided into two categories. The first category refers to ambient energy that occurs naturally. The second category refers to power created by humans and their devices.

Naturally occurring ambient energy takes many forms and can be harvested in different ways.

Naturally occurring ambient energy takes many forms and can be harvested in different ways. For example, sunlight generates heat that can be harnessed as thermal energy. The heat from the Earth's core can also be harnessed as geothermal power. Mechanical energy is another naturally occurring form of ambient power. Waves, wind, and hydropower can all be harnessed to generate electricity.

Solar photovoltaic panels capture ambient energy generated by sunlight.

Solar panels are an application of harvesting ambient energy. ©Chinneeb/Wikimedia (CC BY-SA 3.0)

Less well-known—but with no less potential—are ambient energies generated by human activity. Some are on a large scale while others are so small as to be undetected by human senses.

How Ambient Energy is Captured

Capturing plentiful ambient energy in the surrounding environment is a complex process.

Dr. Vincenzo Pecunia, professor of sustainable energy engineering at Simon Fraser University in British Columbia, Canada, has conducted extensive research on the field of ambient energy harvesting and identified five major approaches to the process:

• Photovoltaics involves capturing energy from light and the sun.

Applications of piezoelectricity (or the production of electricity by materials under stress) include their use in piezo pickups for electric basses and guitars. ©Styroks/Wikimedia (CC BY-SA 4.0)

• Triboelectrics captures electricity from vibrations or friction. (The term “tribo” has its origin in the Greek word tribein, which means to rub).

• Piezoelectrics refers to materials that create electricity under stress. (The term “piezo” derives from the Greek word piezein, to squeeze or press.)

• Radiofrequency energy harvesting is the process of capturing energy from radio waves.

• Thermoelectrics focuses on materials that convert heat into electricity.

These broad categories encompass a variety of ambient energy forms.

Some forms of ambient power harnessing have a long history of use. An example for thermoelectrics is how combined-cycle power plants capture the excess heat that is generated by gas turbines. That heat is channeled to a second set of turbines that produce power from steam. These turbines generate far more power than traditional plants that only generate power from the first set of turbines. This technology has been in existence for more than sixty years.

Another form of mechanical energy harvesting is the regenerative braking in a hybrid-electric car, like the Toyota Prius. It captures the kinetic energy that is generated when the driver applies the brakes and channels a current back into the car's battery.

Can the wheels of a train be another source of ambient energy? ©Togakushi 4/Wikimedia (CC BY-SA 4.0)

Similarly, researchers at the Virginia Tech Center for Vehicle Systems and Safety (CVeSS) are working on developing technology to harvest energy from the rotating wheels of a train.

Even the human body can be harnessed as a source of power. And yes, scientists are working on that, too.

Cell phones, tablets, and the myriad of devices we collectively refer to as the Internet of Things (IoT) emit their own energy, which can be harnessed to power other devices.

One form of ambient power has emerged recently with the advent and growth of electronic devices. For example, cell phones, tablets, and the myriad of devices we collectively refer to as the Internet of Things (IoT) emit their own energy, which can be harnessed to power other devices.

Dr. Peter Spies has been researching the topic at the Fraunhofer Institute for Integrated Circuits IIS in Germany. Describing ambient energy for the online magazine Fraunhofer, he says that small devices “release an energy that we can hardly feel, but which can be used to power brief moments of activity.”

Ironically, this energy is perfectly poised to power other IoT devices. As Dr. Spies explains, “new wireless technologies and microelectronic devices are consuming smaller and smaller amounts of energy, meaning that energy harvesting modules are now a genuine energy self-sufficient alternative to batteries and cables.”

“New wireless technologies and microelectronic devices are consuming smaller amounts of energy, meaning that energy harvesting modules are now a genuine energy self-sufficient alternative to batteries and cables.”

Due to their remote, disconnected nature, these devices have unique needs for power, which also makes them ideal candidates to rely on these same energy harvesting techniques.

The Future of Ambient Energy Harvesting

The ability to harness energy from the environment is a remarkable phenomenon. As society fights the existential battle against global warming, this unique human ability has grown in significance, and it continues to shine. The field itself is diverse and highly promising. Various analyses quantify the global market for energy harvesting systems at anywhere from $400 million to $700 million and project the market to almost double in size, averaging a compound annual growth rate (CAGR) of about 7% to 10% over the next ten years (see, for example, ResearchAndMarkets.com’s “Global Energy Harvesting Systems Market Report 2022: Market to Reach $651.5 Million by 2025 - The US and China to Witness Phenomenal Growth.”)

The growth of the IoT has accentuated the need for more advanced and microforms of energy harvesting. Ironically, those devices are both ideal providers and consumers of that power.

There is little question that ambient energy harvesting in all its forms will be a fixture in the energy industry for many years to come.

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*Richard Laezman is a freelance writer in Los Angeles, California. He has a passion for energy efficiency and innovation. He has been covering renewable power and other related subjects for more than ten years.