• 1 No Poverty
  • 2 Zero Hunger
  • 3 Good Health and Well-Being
  • 4 Quality Education
  • 5 Gender Equality
  • 6 Clean Water and Sanitation
  • 7 Affordable and Clean Energy
  • 8 Decent Work and Economic Growth
  • 9 Industry Innovation and Infrastructure
  • 10 Reduced Inequalities
  • 11 Sustainable Cities and Communities
  • 12 Responsible Consumption and Production
  • 13 Climate Action
  • 14 Life Below Water
  • 15 Life on Land
  • 16 Peace Justice and Strong Institutions
  • 17 Partnership for the Goals
4 Quality Education 7 Affordable and Clean Energy 11 Sustainable Cities and Communities

Could your school run on renewables? Here’s one that does.

330-350 kWh School Energy Requirement

20% of energy requirements Solar Power Output

70% of energy requirements Vortex Micro Hydro System Output


Asia’s development is heavily dependent upon education, and Green School Bali is leading the way in showing how sustainable technologies can make schooling more accessible.

The first of three non-profits started by husband and wife team John & Cynthia Hardy, the school’s aim is “educating for sustainability”, and it is teaching by example.

In Bali that means using sustainable local resources in everything from the unique bamboo architecture to the hybrid renewable power system.

With over 500 students, 300 teachers and 78 buildings Green School Bali needs 330 – 350 kWh of energy to stay operational. Solar power was meeting 20% of that need, with diesel generators providing the balance.

John & Cynthia Hardy founders of the Green School Bali
Source: www.greenschool.org


To expand their sustainable energy output, the school decided against more solar panels in favour of a different sustainable technology – hydropower from the nearby Ayung River.

‘We educate for sustainability, through community-integrated, entrepreneurial learning, in a wall-less, natural environment. Our holistic, student-guided approach inspires and empowers us to be changemakers.’ – Green School Way

Best known by tourists for white water rafting, the longest river on Bali runs 68.5km from the northern mountain ranges down to the Badung Strait at Sanur.

The Green School has now put the river to another use powering its innovative Vortex Micro Hydro System.


The Vortex Micro Hydro System

The Vortex Micro Hydro System is designed and installed in Green School Bali by Belgian company Turbulent. It is only the second of its kind in the world, the first being in Donihue, Chile.

The vortex system channels about 1.4 meter cubed per second of water from an upstream natural dam into a vortex bowl. The water spins a turbine connected to a 16/1 gearbox that spins a generator at 1500 rpm or 50 Hertz. The generator is synchronised and locked into the grid supply through a 250 meter long cable producing 13 kilowatts of continuous power. The power is controlled by an electronic gate at the inlet to the vortex. The control system is also streaming the production and performance data to the Internet, which can be monitored through a smartphone application and shut down remotely in case of emergencies.

The other advantages of the vortex are that it runs 24 hours per day compared to solar, which only operates during daylight hours, and diesel generating plants which typically operate at only 60 – 70% uptime.

Installing the system is not without its difficulties, since a natural river is prone to varying water levels, flooding and debris.

Turbulent VORTEX Demonstration
Source: Turbulent Hydro YouTube channel


Aereal shot of the Ayung River, Bali
Source: Shuttershock


15kW Vortex turbine with more technical details
Source: Turbulent Hydro YouTube channel


So successful has the experiment been that the school believes that within four years their new systems will not only provide 100% of the school’s needs, it will help nearby communities to light and cool their homes.

The system is also a source of learning for students who are being actively educated in environmental science and entrepreneurship.

The Green School, Bali
Source: Shuttershock

“I have visited many different places and many schools but Green School is the most unique and impressive school I have ever visited.” Ban Ki-moon, Former Secretary-General, United Nations


  • lee ann mckee
    Lee Ann McKee

    Director - Marketing & Communications at Green School

  • jasper verredyt
    Jasper Verreydt

    Founder and CEO at Turbulent Hydro

  • Tony Vovers
    Tony Vovers

    Sustainability - reflect, extract only the yield, take care of all the rest.

  • Dita
    Dita Anggraini

    Project Management Associate | Bachelor Graduate of Engineering Physics