“We want to make the energy transition part of everyday activities, such as charging your phone while pushing your child on a swing”

Fernando Borja de Sarachaga and Antíoco Cuesta are the creators of Ecoswing, a swing that can convert human movement into useful energy for charging mobile devices or supplying power for public spaces. This Spanish invention combines sustainability, fun, and technology, all at the service of the cities of the future

Transforming play into sustainable energy: this is the idea behind Play4Energy, a Spanish start-up focused on generating electricity from human movement. Its first invention, the Ecoswing, is a swing that converts this swinging motion into a source of renewable energy, capable of charging mobile phones or lighting public spaces. Designed to raise awareness of responsible energy use and promote sustainable habits, this device offers a practical solution to such an everyday problem as your phone battery dying while you’re out of the house. 

QUESTION. Where did the idea of turning a traditional swing into a renewable energy source that can be used to charge a phone come from?

ANTÍOCO CUESTA. I got the idea when I was pushing my son on a swing at the playground one day. I saw that many parents used this time to look at their phones, but their batteries often ran out. I am a computer and electronic engineer, so I thought of a way to take advantage of that swinging motion to generate electricity. It's about using everyday things like pushing a child on a swing to charge a cell phone. This is how Ecoswing was born, with the goal of solving a common problem like running out of battery, especially when there are no outlets readily available. This environmentally-friendly solution allows parents to charge their phones while playing with their children, combining entertainment and utility.

QUESTION. How does it work exactly?

FERNANDO BORJA DE SARACHAGA. It is a simple idea but rather elaborate in technical terms. The swing is connected to a bar that rotates a rotor attached to special gears. They transfer this movement to a motor with an alternator, converting mechanical energy into electric power. A regulator stabilizes this current before it is then stored in a battery. Finally, the stored electricity can be used directly to charge a cell phone or any other electronic device. Basically, the taller and heavier a person is, the more energy will be generated. This makes it possible to produce electricity from something as simple as swinging back and forth, turning play into immediately usable energy.

QUESTION. What is the capacity of the Ecoswing battery and how many devices can it charge during an average day?

ANTÍOCO CUESTA. The battery can charge up to four cell phones simultaneously, at a slightly lower speed than a conventional outlet. It can also keep four light bulbs on for one day. It could even be used to light up entire parks by using the generated energy to power streetlights. In summary, the battery has sufficient capacity for several hours of continuous use and different practical applications. It’s about making efficient use of each movement of the swing, offering a solution for both everyday emergencies and long-term public energy savings.

QUESTION. Where can we find the Ecoswing, or where do you plan to install it in the near future?

FERNANDO BORJA DE SARACHAGA. We have tested it at public events such as the Mercado de Motores market at the Madrid Railway Museum, where it was very well received. We are currently in talks with towns and cities in Zaragoza, Madrid, Andalusia (Jerez, Malaga, Seville), Castilla-La Mancha, Castilla y León, and Galicia. We are also considering installing it in airports, train stations, and shopping centers, places where it is often difficult to find somewhere to charge your phone. Our intention is to install several Ecoswings before the end of the year, expanding their public visibility and making them easier for more people to use in their everyday lives in various locations.

QUESTION. Is the Ecoswing also designed for adults, or is it just for children?

FERNANDO BORJA DE SARACHAGA. It is also designed for adults. In fact, it is certified for a weight of up to 180 kilos, so two adults could even use it at the same time. In fact, we chose the swing because it is universal. It takes us back to our childhood and is attractive to people of all ages. In this way, we not only make it possible to charge electronic devices but also give adults and children alike the chance to have fun and healthy moments, making the interaction with environmentally-friendly technology more attractive.

QUESTION. What impact do you expect it to have in terms of sustainability?

FERNANDO BORJA DE SARACHAGA. Our goal is to raise public awareness by getting people to play an active role in generating renewable energy and promoting more sustainable cities. We participate in European projects such as the Zaragoza Sandbox, which is focused on urban sustainability. We directly contribute to some of the 2030 Agenda’s key goals, promoting innovative renewable energies. In the long term, we hope that initiatives such as Ecoswing will represent a significant percentage of the urban energy mix, helping reduce our dependence on polluting energy sources and promoting more sustainable habits. We want to get citizens to play an active role in the energy transition.

QUESTION. Are there any similar initiatives in Spain or internationally?

ANTÍOCO CUESTA. Yes, there are similar initiatives at the European level in some Nordic countries, and also in Japan. These regions are very committed to sustainable energy. We don’t know of any other similar proposals in Spain, but we want to be at the forefront of these kinds of solutions in Europe. There is a growing global interest in harnessing the energy generated by daily actions, and Ecoswing seeks to lead this trend in Spain by providing practical, environmentally-friendly, and effective solutions to everyday energy-related problems.

QUESTION. In terms of maintenance, does the Ecoswing require constant or complex revisions, especially when installed in a public facility?

FERNANDO BORJA DE SARACHAGA. It is designed to ensure that maintenance is simple and economical. The mechanics are remarkably similar to a conventional swing. The electrical part requires a basic annual revision and uses easily replaceable plug-and-play type parts, so any repairs can easily be carried out by municipal workers. We also have spare parts ready in the event of any specific needs. Its sturdy and easy-to-maintain design makes it ideal for public facilities and means that it can be installed not only in parks, but also in other high-transit areas such as squares, transport hubs, or beaches.

QUESTION. Are you currently working on any other products related to sustainable energy generation?

ANTÍOCO CUESTA. We have two more products in mind. One takes advantage of the movement generated by older adults when using outdoor gyms to charge batteries that light up these spaces at night. The other is based on developing special flooring for shopping centers or heavy-transit spaces that would transform the energy of people’s steps into electricity, ideal for lighting entrances or powering automatic doors. We want to make the energy transition part of everyday activities, promoting greater awareness of the efficient and ecological use of energy in various day-to-day settings.