Topic Resources

Tools Used
Initiated By
  • Ripple Energy
  • Energy suppliers
  • Generated 65,000 MWh of electricity and avoided the release of 34,000 metric tonnes of CO2 annually 
Landmark Case Study

Co-Ownership of Wind Farms

What if you want to move away from gas and oil, but rent, are about to move, or can’t afford solar panels? If your energy supplier has not already pledged to go green, you have few options. The co-ownership of wind farms engages and makes it practical for more homeowners and renters to buy wind-generated power.


Sarah Merrick from Ripple Energy noticed that there were few options for consumers to buy wind-generated power, that big projects were more cost-effective, and that buying part of a wind farm was 2/3 less expensive than rooftop solar.

Delivering the Program

Note: To minimize site maintenance costs, all case studies on this site are written in the past tense, even if they are ongoing as is the case with this particular program.

To make the approach practical for a larger audience, Ripple worked with energy supplier partners. Ripple supplied its power to these energy suppliers, who then provided corresponding credits to their clients who were co-owners of their wind projects. The suppliers then supplied this cheaper, greener renewable energy to the members’ homes via the grid. Since Ripple managed the co-op and energy supplier relationships, and built and maintained the wind farms, the approach was as easy for members as it was before they joined. (Financial Incentives; Overcoming Specific Barriers)

The benefits for consumers included the following.

  • Stable, reduced costs. Co-owners paid their share of construction costs, then only paid ongoing operating costs that were much less than the market price for electricity.
  • Reduced carbon footprint
  • Helping to add new green power sources to the grid
  • Cost savings compared with a do-it-yourself approach, due to economies of scale
  • Cost savings compared with other green power alternatives (65% cheaper than installing rooftop solar)

Ripple started with co-ownership by 907 people of a single wind turbine called “Graig Fatha” in Coedely, south Wales. The project quickly sold out.

Launch of Graig Fatha

In 2023, at the time of writing this case study, its second project was being built in Kirk Hill, South Ayrshire, Scotland. It was to have eight turbines and 5,600 co-owners and would produce 18.8 MW of electricity – enough to power 20,000 households. The minimum investment was £25, and the project received 16,000 reservations in one week, in February 2023. This project was also partially financed by 19 investors; to help fuel expansion, Ripple had allowed a portion of its newer projects to be financed through co-ownership by investment firms. For example, Virgin Money had been an investor in Ripple’s second and third projects; it had a goal of reducing carbon emissions by over 50% across its investments by 2030.


Building the Kirk Hill windfarm

The following table summarizes the key barriers to action and how each was addressed. (Overcoming Specific Barriers)


How it was addressed


Consumer rented or was about to move – reducing the incentive for investing in home solar or wind power


Consumer lived far from the wind project

·         Consumers retained their shares when they moved, and participated from anywhere served by Ripple-associated energy suppliers

Consumer’s energy supplier had not developed green energy sources

·         The only additional responsibility for Energy suppliers was handling the accounting

Cost was prohibitive

·         Investment was incremental (buyers could decide how many shares to purchase)

·         Costs were significantly reduced due to economies of scale

Consumer lacked relevant expertise and time

·         All aspects were managed by Ripple, so the consumer didn’t have any added responsibilities compared to before membership


Presentation on Ripple Energy

Financing the Program

The main innovation with this approach was co-ownership combined with the ability to buy energy / pay ongoing operating costs through one’s regular energy supplier. This dramatically expanded the market for affordable green energy and gave consumers the ability to cut their carbon footprint and help add new green power sources to the grid.

To help fuel expansion, Ripple allowed a portion of its second project to be financed through co-ownership by investment firms.

Measuring Achievements

Reductions in kWh were based on actual (first project) or predicted (second project) electricity generated from wind power. Reductions in greenhouse gas were calculated based on Kwh used.


Feedback was provided through the reduced utility bills.


  • First project: 4,800 MWh of standard electricity and avoided the release of 2,530 metric tonnes of CO2 annually
  • Second project (projected): 60,300 MWh of standard electricity and avoided the release of 31,760 metric tonnes of CO2 annually



Landmark Designation

This case study was was compiled in 2023 by Jay Kassirer based on information provided in the reports below. The program described in this case study was designated by our Energy Conservation and Efficiency panel in 2023.

Designation as a Landmark (best practice) case study through our peer selection process recognizes programs and social marketing approaches considered to be among the most successful in the world. They are nominated both by our peer-selection panels and by Tools of Change staff and are then scored by the selection panels based on impact, innovation, replicability and adaptability.

The panel that designated this program consisted of:

  • Arien Korteland, BC Hydro
  • Doug McKenzie-Mohr, McKenzie-Mohr Associates
  • Sea Rotmann, Sustainable Energy Advice Ltd.
  • Lester Sapitula, Pacific Gas and Electric Company
  • Reuven Sussman, American Council for an Energy-Efficient Economy
  • Marsha Walton, New York Energy Research and Development Authority


  • The idea of co-ownership could be used to support other large green energy projects such as solar power farms and waterpower plants. For example, Bristol Energy Cooperative has successfully completed eight share offers and brought 17 clean energy projects online since starting in 2011 - including two solar farms, grid-servicing battery storage and 14 rooftop solar arrays.
  • A similar approach is already being used by car-share companies that enable members to share a fleet of greener cars (e.g. Virtucar.)

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