Wind and hydroelectric power are two examples of commonly used kinetic energy sources. What else is there? Gravity combined with large drops can be a kinetic energy source. Back in February 2023, I wrote about using the vertical drop found in abandoned mine shafts where large payloads of material like sand or gravel could be dropped to power turbines and generators.

Another kinetic energy source that we can harvest comes from our feet on sidewalks and floors and from cars and trucks we drive on roads.

Speaking of feet, our shoes can become portable power generators with piezoelectric devices in the soles and heels producing enough electricity to power mobile devices.

As cars and trucks drive over roadways embedded with piezoelectric harvesters, the conversion of small amounts of mechanical surface force can be turned into electricity.

The floors in our homes and workplaces can become kinetic energy harvesters.

Imagine a crowd going into a sporting event and as they walk to and through the stadium, they generate enough force to power the stadium lights, or electricity that can be put into battery storage for later use.

So why aren’t we harvesting the kinetic energy we produce from daily activities?

The Paris Metro station pilot project is worth noting. Turning a turnstile into a power source is a neat idea. At the Miromesnil station, 27,000 people pass through those turnstiles every day. Iberdrola has estimated that if all the Paris Metro stations were to convert to turnstile turbines the subway would generate 136 Megawatts annually, almost enough energy to power the entire Metro system and equivalent to removing 30,000 tons of CO2 from the atmosphere annually.

The retrofit of the Paris Metro, however, is not happening because the powers that be have concluded that the cost of converting the entire system to turnstile turbines would be too expensive. Iberdrola, however, believes that the technology has a future and is looking to other cities to deploy turnstile turbines.

In 2012, Innowattech, an Israeli company, proposed putting piezoelectric harvesters in roadways noting that one kilometre (0.62 miles) would produce 400 Kilowatts of power, enough to light and heat over 160 homes.

A 2018 UC Berkeley study looked at the per-kilometre cost of installing piezoelectric harvesters in roads at $1 million. The Interstate Highway System in the United States is 78,465 kilometres in length based on 2020 data. To convert the Interstate to become a kinetic energy source would exceed $80 billion. The harvested piezoelectric energy from two lanes with embedded piezoelectric harvesters would produce more than 31.3 million Kilowatts. That would be equal to the energy requirements of 27,000 U.S. homes monthly. Taking the average CO2 emissions produced by American homes at 40 tons per year, the power harvested from Interstate drivers would remove over 1 million tons of CO2 annually.

Staying the course in how we produce the electricity we consume today is cheaper per Kilowatt than these novel kinetic technologies at present. Nevertheless, kinetic energy alternatives such as the turnstile turbines in Paris and the piezoelectric-implanted roads and walkways in the UC Berkeley study, if scaled, would offer zero-emission-generated electricity at a comparable cost.

The Paris Metro’s turnstile turbine technology is a good thing. We need a lot more of these novel technologies and the political and business acumen to make our future one where the energy we consume doesn’t end up compromising the environment we bequeath to future generations.

In pursuit of mitigating climate change caused by our modern industrialized world, not putting research and funding into these types of energy sources is in my opinion a mistake.

I had some serious concerns about laying down photovoltaics on a road surface largely because of wear and tear. Solar Roadways claimed their solar road panels could withstand weights of up to 113,000 kilograms (250,000 pounds) which would certainly handle the largest semi-trailer rigs or even an Abrams battle tank.

Solar Roadways weren’t alone in proposing paving roads, parking lots, and sidewalks with solar panels. A French company, Colas, developed Wattway, resin-reinforced solar-panel sheets that were installed in a first test road covering one kilometer (0.6 miles) near the city of Caen, in Normandy. At the time the French government touted the technology as being “unprecedented,” and that this small stretch of road would generate enough electricity to power the streetlights of a neighbouring town of 3,400 residents. The ultimate goal, the government stated, was to pave 1,000 kilometers (621 miles) of road with Cola’s panels over five years.

This is what this $5.2 million USD road looked like shortly after installation.

This is what parts of the roadway looked like (see image below) by May 2018 when 90 meters (300 feet) of it was beyond repair and had to be demolished.

It turned out that Thunderstorms, local farm tractors, and other traffic caused photovoltaic panels to break (see picture below).

And then there were falling leaves and debris that reduced the amount of power the panels could generate. The solar road at best produced 80,000 kilowatt-hours (Kwh) annually although the trial target was almost twice that. And by July of this year, the yield annual average had dropped to 40,000 Kwh. With such declining results it was time to pull the plug.

When I wrote about Solar Roadways back in 2014 I wondered about the durability of creating roadways paved with solar panels. I thought about winter snowfalls, freezes, and thaws, about oil spills, garbage on the road, falling leaves, roadkill, and more, and wondered how a technology like this could endure.

It appears as of right now, that the pioneers trying to make this technology work have discovered that “unprecedented” and being named the Google Moonshot of May 2013, doesn’t necessarily mean you will succeed.

Why not put elevated solar panels on the sides of roadways instead considering you have clearance and rights of way that could facilitate this type of implementation. Or you can try to use the power engendered by wheels running over pavement through the installation of piezoelectric power generators. The latter continues to be a technology of interest to university engineering labs and the like. But it appears little progress has been made to turn this technology into a commercial and operational success. The only reference to an installed site that I could find is a 10-meter (33 foot) strip of asphalt along Route 4, an old coast road in Israel where it generated in a test 2,000 watt-hours of electricity.

It appears we have a long way to go before our roads become sources of energy whether solar or piezoelectric, rather than locales where massive amounts of energy get burned daily contributing to global warming.

The device is called the BOLT (one can be seen next to the U.S. quarter in the image below). It is a product of the Cornell University NanoScale Science and Technology Facility. This summer it will go into production marketed by MicroGen Systems Inc., of Ithaca, New York, a company spun out from the university to continue to develop commercial applications.

The BOLT brand covers a range of piezoelectric vibrational energy harvesters, or PZEH for short. You can see some of the models on display in the picture below.

Each is a micro-electromechanical power generation system or MEMS, that harvests energy from vibration and can last twenty years or more before needing replacement. A PZEH can be mated to a rechargeable battery extended its life, or it can work with an adjoining ultra-capacitor, eliminating the need for any battery.

Where will the BOLT be used?

To power devices that currently rely on the coin-cell type batteries we see in all kinds of devices. Today we throw away 164 million of these flattened cylinders every year. Coin-cell batteries are used in watches, stacked together and used for transportable lighting, power handheld calculators, and are used in wireless sensors.  In particular it is expected that the BOLT will revolutionize the engineering of the latter and feeding the growth of the Internet of Things.

You can watch a demonstration of MicroGen’s piezoelectric BOLT on YouTube.

Piezoelectricity is energy produced from pressure. The energy gets generated when an automobile, a truck or a train passes over a surface in which piezoelectric devices are embedded. Even a sidewalk or dance floor can be outfitted with such devices.

The cigarette lighter in an automobile is a good analogy for how piezoelectric devices work. In the case of the lighter a spring-loaded plunger is depressed producing high voltage to heat the embedded element.

Piezoelectric devices are embedded within existing infrastructure. As a result they can work day or night, in almost any climate and in any weather conditions. The energy these devices generate is in some sense serving to recover the energy expended by the vehicles that drive over them. With no footprint on the land like solar and wind, piezoelectric technology can include data collectors making roads smart to monitor and report on traffic conditions, vehicle type and weight, and vehicle velocity. And wherever piezoelectric devices are embedded they are practically impossible to damage or steal.

Innowattech Energy Harvesting Systems is an Israeli engineering firm that has developed the IPEG (TM), the Innowattech Piezo Electric Generator, a device that deforms from the weight of a person, vehicle, train or aircraft as they pass over. IPEGS can be installed in asphalt, concrete or composite material-surfaced roads. The company is working with the Italian government to install IPEGS in a highway running between Venice and Trieste to operate all road lighting.

How much energy can a device like an IPEG produce? A single kilometer (0.62 miles) of roadway with IPEGs installed can generate 400 kilowatts of energy based on average traffic conditions. The busier the road, the more energy it produces. Heavier vehicles means more energy gets generated.

On a personal level imagine owning a pair of shoes with soles that contain piezoelectric technology to power all of your mobile devices from phones to music players to flashlights with every step you take.