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How do you create a carbon free future? Step one: Envision it.

Updated: Sep 15, 2021

By Jack Kelly and Lauren Kuntz

Movements for climate change action have been building momentum. One must only look as far as recent climate strikes occurring globally and the groundswell of support for Greta Thunberg, exemplified in the power of her speech given to the United Nations in 2019, and tempered only by a global pandemic. There has never been greater support for climate action than right now, but what action are people calling for, exactly? There is a growing desire for society to reach a carbon free future, but how do we get there?

There have been countless solutions to climate change suggested, but none has emerged a singular silver bullet, and for good reason the answer is unknown, and will be extremely complex. Sure, wind and solar will play a vital role, but they alone can’t solve the whole problem. Questions remain about the cost-effectiveness of storage to balance out the intermittency of renewables; the ability to fully replace liquid fuels with carbon-free alternatives; the role that efficiency or demand-shifting technologies might play in easing the burden on the electric grid. We, the authors, believe it is okay to be unsure about the answer climate action does not necessitate a complete roadmap. Given the many uncertainties about our future energy system (How much demand will there be? How will prices of battery technologies change? Will nuclear fusion become a viable option?) it isn’t necessary, nor even feasible, to plan out in advance the location of every renewable plant, transmission line, and EV charging station. Needs and possibilities will change over time, and the best energy choices today likely won’t be the same tomorrow. However, being able to envision the mountain we must climb to get to a carbon free future is the first step to reaching the summit.

In the words of the late David MacKay, former Chief Scientific Adviser to the UK Department of Energy and Climate Change and Cambridge Professor,we need energy numbers, and policies that add up.’ It’s more than just turning off the lights or unplugging appliances we need to create an energy system where carbon free energy production adds up to meet our growing energy demands. This was the weight of the task presented to us when, as undergraduates at MIT and Harvard, our professors independently tasked us with the same project: to design a carbon free energy future that actually ‘added up’. What at first seemed like a simple end of course assignment just add some wind and solar quickly transformed into a plethora of difficult decisions. Every small choice seemed to run into implications for the future we’d live in. If we covered large swathes of land with biomass for energy, we might run into food security problems or biodiversity collapse. Would we be able to get buy-in for a future where demand was reduced where we consumed less and reused more? It was this task that both terrified and excited us to the point where we knew this wouldn’t just be a project we’d hand in and forget about - this would be the project we would dedicate our lives to answering.

Designing a carbon free energy future that adds up is a task we adamantly believe everyone, not just climate experts, must address. Undertaking this challenge facilitates conversations about the ‘how’ behind taking climate action. Yet ordinarily, designing a low carbon future that is simultaneously aspirational and realisable requires mathematical modeling of energy systems and the electric grid not exactly an accessible process.

We decided to change that. We created a new learning platform, gReenvision, that does the mathematical modeling for you. Built on simulations of the electric grid, the website is designed to give you the chance to envision a carbon free future both for an individual household, as well as for the entire U.S. electric grid (you can find a guide to the website at the bottom of this article). It aims to help you think through some of the decisions and trade-offs we must make to build a carbon-free electric grid, using the U.S as a case study. As with any model, this has meant making some simplifications: namely choosing to focus on just the electric grid. The challenges of decarbonization cut across all sectors from transportation fuels to land use. However, since most decarbonization pathways rely on electrifying as much energy consumption as possible and supplying that energy with carbon free electricity sources, creating a carbon free electric grid is an important piece of the puzzle.

Starting with a carbon emission reduction goal and a year at which you will reach it, gReenvision then asks you to think about costs, additional environmental impacts, and construction requirements. It’s up to you to decide what’s possible: Are we willing to pay quadruple the price of electric bills for an entirely renewable grid? Maybe we’re ok using more nuclear power, and accepting some of the risks and challenges of waste disposal? Or if we’re not, what other solutions will we therefore need to pursue instead?

gReenvision isn’t designed to be the one true solution; there is lots of uncertainty — from forecasting demand growth to predicting how technology costs will change (and the negative feedbacks between costs and consumption). Instead, it was vital that we enabled you to change the assumptions - both yours and its own. If the cost of grid-scale electricity storage were to fall by half, how would that change which carbon-free futures might look most feasible? Or what if we were able to shift consumers’ demand for electricity, decreasing system-wide electrical loads at peak hours? It gives you the power to ask ‘what if’, and to think about which technology advances would have the most meaningful impact.

Using gReenvision, you can technically fiddle with the knobs to hit any emissions target.. The trick is to understand the impacts of your decisions. The main idea is to start imagining and visualising the physical changes that need to be made and the limitations that exist to reduce carbon emissions, as well as how difficult the transition may be. Yet the best way to face the difficulty is to know what we’re up against. By understanding the complexity and size of the problem, those pushing for climate action will be equipped with more than just another voice in the crowd. They will have the foundational understanding to push for more realistic and impactful solutions.

It is often too easy to sit back and demand action any action be taken in response to climate change because we believe it to be the right thing to do by the planet. Yet by doing so, we risks overlooking factors such as effectiveness, inclusivity, and cost burdens which can differentiate any action from truly impactful action. Just as climate is deeply entwined with our planet, climate policy will be deeply entwined with our society. It’s vital that we understand the connections. Any climate policy will be required to balance competing values, and we need to understand and accept the necessary compromises. gReenvision is a tool that will allow anyone to grasp some of these interconnections outlining economic, environmental and time impacts of our climate and energy decisions. It challenges users to think about how our values across these domains can both oppose and complement one another, and places balancing different outcomes as a priority.

What carbon free energy future would you envision? What compromises might it take to get there? We hope you’ll take the time to not just design your own energy future, but to share that vision. Have conversations about it. Let’s develop the understanding of trade-offs necessary to create impactful climate action.

Steps to using gReenvision:

  1. Go to

  2. Choose whether you wish to reduce emissions for an individual home or the entire U.S. electricity grid.

  3. Set your emissions reduction target.

  4. Design your grid makeup (solar, wind, batteries, etc.).

  5. Ensure your designed grid meets your emissions reduction target.

  6. Adjust the costs of each technology.

  7. Analyse the price of electricity from your designed system.

  8. Check the environmental impacts of your decisions.

  9. Check the construction timeline to see capacity additions.

  10. Adjust the amount of transmission to see trade-offs with generation capacity.

  11. Compare the rate of construction required for your future grid to historical build rates.

  12. Continue to iterate over your decisions and optimise your future system.

  13. Get your gReenvision summary.

  14. Share your results!


Jack Kelly is a DPhil student in Engineering Science at the University of Oxford. His studies focus on

wind energy, in particular that control strategies of wind turbines. Previously he has completed a

Bachelor of Science at Harvard University in Environmental Engineering.

Lauren Kuntz has a PhD in Earth and Planetary Science from Harvard University. She is currently CEO and Co-founder of Gaiascope, an energy quant fund focused on accelerating our energy transition.

Art by Aishah Wilson


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