Generating power with your footsteps and other curious ways to get energy

Energy can be harnessed from the environment in many ways, including piezoelectric energy, which can generate the energy from your footsteps, heat recovery systems, energy from tides and waves, osmotic power, etc. The 21st century is going to need all possible sources to decarbonise our activities. We will take a look at the most unique ways to generate energy.

Footsteps that generate energy and systems that harness body heat

Each footstep can generate about 7W of instantaneous power. It may not seem like much, but it's enough to charge a phone. For some time now they have been installing piezoelectric generators in a number of places that can turn footsteps into useful electricity by compressing a crystal inside a floor tile.

Railway stations, nightclubs and amusement parks with paths along which a large number of people walk have been converted into testing grounds to measure the usefulness of these devices in surroundings where there is high traffic density.

For example, at Stockholm Central Station in Sweden, which happens to be one of the world's cities that generates more energy than it consumes, a number of technologies were combined in about 2010 to make this railway station even more efficient. A number of piezoelectric generators were placed on ground surfaces with a high density of traffic, such as stairs, to generate the energy that powers the station's lights, a heat recovery system was also designed that used the excess body heat generated by travellers to heat a nearby building.

Generators submerged under water: This is how tidal generation works.

Tidal energy is energy obtained from the tides, specifically from water flowing as a result of the ebb and flow that produces high and low tide. This is what we call tidal energy and although it is currently in a number of experimental phases, there has been significant progress as a result of advancements in wind energy.

There are many ways of capturing the tides: Some look a lot like wind turbine blades and others are more like propeller blades. For example, in Strangford, Northern Ireland, they use two large blades that move with the rising tide. And in France, on the Rance River, they have a 240MW plant of this type of technology. From the outside it looks like a conventional bridge but it is continuously generating energy by means of a battery of generators whose axes are aligned with the flow of water. The advantage of this type of energy over wind power is that the power achieved is enormous and constant.

Wave Energy: Wave Energy

Tidal energy is sometimes confused with wave energy. The latter takes advantage of the differences in height between the high point and the low point of the waves to turn a rotor, and there are also many different designs, all relatively simple and cheap, although they generate relatively low power outputs compared to other types of renewable energies.

Even so, it is still being developed at full capacity because any way of generating clean energy is essential to our development. With regard to wave energy, we find different systems of use: Floating devices assembled in the form of columns attached to the seabed with a cable, consisting of a floating part and a non-floating part, oscillating water column systems, wedges that are flooded by the waves which exert pressure on a small turbine area, and articulated surface systems resembling worms which consist of modules that imitate the waves and capture their relative movement.

The possibilities are vast, so this energy continues to progress every day with new ideas and ways to capture the energy of the waves.

Osmotic energy: Extracting energy from the difference in salinity

One of the most "futuristic" ideas for extracting energy from the environment is osmotic energy, sometimes called blue energy, and which consists of two complementary technologies that enable energy to be extracted from different bodies of water with different salinities.

Although this involves a very intricate mechanism, it can be broadly summarised as follows: Fresh water mixes with salt water, which generates an osmotic pressure that is able to move a complex system of turbines and this generates electricity.

This system has great advantages, since in addition to being a clean and renewable energy and providing constant energy, regardless of weather conditions, it can be generated in any area of the world, so sustainable energy could be ensured for the entire planet, even in remote areas.

Its biggest disadvantage is the high initial cost, associated with the installation and the necessary investment. In addition, if we compare this energy with fossil fuels, its cost is much higher, almost double the price per megawatt.

The environmental impact of alternative energy generation

Although the costs of current fossil fuels are much more affordable for everyone, it is important to remember that obtaining energy by these means releases harmful compounds into the atmosphere, too many to make our planet sustainable.

However, renewable energies also have local impacts such as land use or they require rare materials which are not always easy to obtain.

And what about new capture technologies? Piezoelectric generation requires a high level of metallic and crystalline components, energy recovery involves the loss of part of the energy and tidal energy can affect fauna and flora, as can wave power and osmotic power.

It is not easy to strike a balance with the least possible impact on the electricity mix, and this will be one of the greatest challenges of the 21st century. We will probably have to resort to unusual combinations such as mixed wind-photovoltaic systems, wave and tidal energy systems, using the surplus heat from servers connected to the Internet for climate control in homes, and public buildings where the lights are turned on by the energy generated by the revolving door in the foyer.

It is important to remember that the search for these "crazy" ways of capturing the energy that surrounds us in our daily lives should not cease, so 100% renewable energy from sustainable sources reaches every home.