To move from fossil fuel use to local renewables, communities need the right knowledge, skills and tools. CAT graduate Anna Hartley introduces CELESTE, a new system that enables anyone to explore the potential for renewable energy projects in their local area.

It is widely acknowledged that to meet global net-zero carbon goals and mitigate the worst effects of climate change, fossil fuels must be replaced as much as possible by renewable energy. While we hear a lot about large-scale multi-million dollar solar and wind farms owned and managed by corporations and states, small-scale renewable energy communities (RECs), in which citizens come together to produce, exchange and use renewable energy, have also been identified as a key component in this transition.

No two RECs are exactly the same, but the EU describes them as legal entities that combine both non-commercial economic aims with environmental and social community aims. They share open and voluntary governance, shared ownership and control by members (who are also consumers), and have as a main purpose creating social and environmental benefits instead of financial profits.

Sounds fantastic, right? Yet in France, where I live, RECs are little known and poorly understood. What if there was a programme that could fast-track the development of RECs while also raising awareness about energy systems more broadly? That’s the question I investigated during the dissertation period of my MSc Sustainability in Energy Provision and Demand Management at CAT.

Bridging the knowledge gap

Assessing a site for its suitability for a renewable energy project is not overly complex, but it does require some specialised knowledge. If we want thousands of small communities all over the world to start building them, it seems evident that there should be more tools available that can provide this.

I felt sure that by pulling together a range of freely available online datasets I could produce a program designed for non-expert users that would do simplified feasibility assessments for RECs. This should only require the users’ geographic location and their willingness to engage in some energy futuring to operate.

Harnessing digital tools

As the research progressed, my conviction that a tool like this was necessary and useful grew. Almost all the research and discussion around RECs focuses on their technical, economic and policy dimensions, with little attention paid to involving the broader public, who are the very people responsible for creating and running RECs.

Secondly, digital tools concerning renewable energy development are overwhelmingly aimed at expert users, very limited in scope, and often expensive to access.

By the completion of my dissertation period, I had created a prototype program known as the CELESTE Decision Support System. CELESTE stands for Créons des Énergies Locales, Écologiques, Solidaires et Transformatrices Ensemble (Creating Local, Ecological, Supportive and Transformative Energy Together).

CELESTE functions as an educational tool that uses the wealth of publicly available data, repackaging it in a useful way, rather than developing new complex systems. It is also modular and expandable, meaning that what is currently available is just the beginning and there is no limit to the number and type of modules that could be added.

Whether the user takes action after using CELESTE is up to them, but I hope they will at least feel more informed and engaged in the conversation around renewable energy. In this way, CELESTE is just as important as an engagement and educational tool as a systems modelling tool.

How does CELESTE work?

CELESTE has a simple interface and is designed to walk the user through four key stages, much like a carbon footprint calculator.

1. Start here: The user enters the name of their commune in France to view data such as the commune’s population, total energy consumption for the most recent year available (in this case, 2021), and the portion of that consumption that corresponds to the residential sector.

2. Adjust variables: Here, the user begins imagining their energy future, toggling different variables to see how these impact upon the commune’s electricity demand, such as the year (up to 2060), population predictions, climate change scenarios, and consumption patterns like electric vehicles and air conditioner usage. A bar chart clearly shows the actual electricity demand against the future demand as per what the user has inputted.

3. What’s possible?: At this stage, the user gets to start designing a new energy system. They are presented with a basic feasibility assessment for a solar PV or onshore wind farm in their commune. The user can toggle the size of the installation and see how this impacts physical size, what percentage of the commune’s electricity need this would meet, costing and payback time, and CO2 emissions reduction.

4. Next steps: Finally, the user is shown recommendations about ways to reduce their energy consumption, local and national organisations that support RECs, EC consultants who can begin advising them on their REC journey, and a list of RECs already functioning in their geographic area that they can visit and investigate.

What’s next?

CELESTE is still a prototype, built in Google Sheets and using predownloaded datasets for a limited number of communes. Many of the calculations applied to the data are quite rough, using rule-of-thumb estimates when trusted, peer-review data is missing. However, as better information becomes available, it can easily be integrated, improving the quality of the outputs.

Who can use CELESTE?

I have registered CELESTE under a Creative Commons licence so that it can be shared, adapted, and remixed by any non-commercial entity that wants to take it further.

While CELESTE is only currently crunching data for France, there is no reason why it can’t be adapted to anywhere in the world. Countries could substitute communes with their own administrative divisions, plug in their local electrical and population datasets, and adjust calculations – for example about typical electrical demand of an electric vehicle per annum, and the cost of renewable technologies – according to the most up-to-date information for their area.

No two countries will have the exact same kind of data, so it is exciting to consider the range of additional modules that could be designed and incorporated into CELESTE. Hydroelectricity potential, battery storage and grid flexibility, thermo-sensibility metrics, and access to local grants and subsidies are just a handful of the modules that could be added, given access to the right data and with the right minds on the job.

Furthermore, CELESTE could be used by existing RECs to see how their installations would perform under different climate, temporal and behavioural conditions, or by schools and institutions as an educational tool to improve understanding of the topic.

Explore CELESTE

About the author

Anna Hartley is an Australian writer who has lived in Paris and Beijing since 2011. Her work has been published in The Washington Post, France 24, Forbes Travel Guide, The Houston Chronicle, The New Zealand Herald, The Vancouver Sun, the Beijinger, and Babbel Magazine. She graduated from CAT’s Sustainability in Energy Provision and Demand Management in 2024.