The Green Voice: Solar Speaker used at Madrid's environmental demonstrations through WWF

The Green Voice

Solar Speaker used at Madrid's environmental demonstrations through WWF

A twelve-sided solar loudspeaker for the climate marches in Madrid

The Green Voice is a twelve-sided solar speaker used in the 2019 climate demonstrations in Madrid, with the collaboration of WWF. Light Humanity built it together with Ingeniería Acústica García-Calderón.

  • What it is: a twelve-sided solar speaker that spreads sound equally in all directions.
  • What for: so that the voice of the marches can reach everyone.
  • Partners: Ingeniería Acústica García-Calderón, a Madrid acoustics company, with the collaboration of WWF.
  • The message: in the project photo, the speaker's cart carries Light Humanity's “You + Sun” poster against energy poverty. The photo was taken indoors, and there is no record of that poster being taken to the marches.
  • Who drove it: Light Humanity, the NGO founded by Eugenio García-Calderón Huerta.
The Green Voice: twelve-sided solar loudspeaker with two panels, on a cart with a sign
The Green Voice: the speaker, its two solar panels and the “You + Sun” poster. Photo: Light Humanity archive
“You + Sun” poster against energy poverty on the cart of The Green Voice
Detail of the “You + Sun” poster on the cart of The Green Voice. Photo: Light Humanity archive
Black dodecahedral sound source by Ingeniería Acústica García-Calderón on a tripod
Dodecahedral measurement source from IAG, the company that collaborated on the speaker; this is not The Green Voice. Photo: IAG

Madrid marched for the climate in 2019: global strike and COP25

That year, Madrid saw these two climate marches, among others:

  • 27 September, global climate strike: Fridays for Future called a student and consumer strike and an afternoon demonstration, at the end of a week of mobilization (Time Out).
  • 6 December, Climate March: in the middle of the COP25 climate summit, it was called for six in the evening at Atocha station (Energías Renovables). Thousands of people, half a million according to Ecologistas en Acción, filled the main thoroughfare of central Madrid (EFE, in Orain).
  • WWF at the march: WWF joined the Climate March on 6 December, according to its COP25 bulletin of 7 December 2019. Its banner read “It's now or never” (photo by John Englart).
“Madrid has become the cry of all the world's climate struggles” — Juan Carlos del Olmo, director of WWF Spain (WWF bulletin, 07/12/2019)
Climate demonstration in front of the Cibeles Palace in Madrid in September 2019
Global climate strike in front of the Cibeles Palace (Madrid, 27 September 2019). Context photo: The Green Voice does not appear. Photo: Nicolas Vigier / Wikimedia Commons (CC0)
WWF's “It's now or never” banner at the Madrid Climate March, 2019
WWF contingent at the Madrid Climate March (6 December 2019). Context photo: The Green Voice does not appear in it. Photo: John Englart / Wikimedia Commons (CC BY-SA 2.0)

A dodecahedral speaker made with a Madrid acoustics firm

Sound sources shaped like a dodecahedron radiate equally in all directions. That is why acoustic engineers use them to measure sound insulation between rooms or the reverberation of a space (IAG DD5 data sheet).

  • The partner: Ingeniería Acústica García-Calderón (IAG), an acoustics consultancy headquartered in Madrid with a team that has more than 25 years of experience, according to its website.
  • What it does: measures noise and vibration, produces noise maps, carries out insulation tests in buildings and looks for solutions to environmental and workplace noise problems (IAG).
  • What it makes: ultralight omnidirectional sound sources for acoustic testing in buildings.
  • In The Green Voice: the speaker was made in collaboration with IAG and has the same dodecahedral shape as its measurement sources.

“You + Sun”, Light Humanity's message on The Green Voice cart

In the project photo, the speaker sits atop a white Light Humanity T-shirt, with a solar panel on either side. Below it, a wheeled cart carries a large sign.

  • The slogan: “You + Sun”. And underneath: “Together you can end energy poverty and save the planet”.
  • The idea: to use the Sun's energy on trips and adventures with Light Humanity's solar phone chargers and lamps.
  • The cause: according to the sign, every purchase of a Light Humanity solar product paid for a solar lamp for a family without electricity, such as the riverside families of the Amazon who relied on kerosene for light.
“Two problems and one solution: sharing the Sun's energy” — Light Humanity (Energías Renovables, 13/05/2019)

In May 2019, Energías Renovables reported that Light Humanity, founded at the end of 2018, had pledged to donate one solar lamp for every lamp it sold and was preparing its second distribution campaign in Breves (Brazil). That story continues in Light of the Amazon and the Solidarity Solar Shop.

Solar energy on the streets: from Solar Pedalling to The Green Voice

Before founding Light Humanity, Eugenio García-Calderón crossed Spain on a solar bicycle to champion clean energy within everyone's reach (Energías Renovables). These other projects from the lab also took solar energy onto the streets or into the classroom:

  • Solar Pedalling (2018): a tour of Spain by solar bicycle against the sun tax, organised by Zima Project, the forerunner of Light Humanity.
  • Solar Bicycle: an electric bicycle with a trailer of solar panels.
  • School Outreach: talks in schools on renewable energy and mobility.