Solar photovoltaic, wind and hydroelectric power are enough to produce all the energy the United States needs. By 2050, renewable sources will meet the country's needs, doing away with the more traditional fossil fuels, systems for the direct capture of carbon dioxide from the air, bioenergy, blue hydrogen or nuclear power. An unrealisable hypothesis? Not at all — a concrete plan that is simply waiting to be implemented.

The Stanford professor's 100% renewables roadmap

In the roadmap recently published in the scientific journal Renewable Energy, professor in the Department of Civil and Environmental Engineering at Stanford University and director of the Atmosphere/Energy programme, Mark Jacobson, sets himself apart with his 100 per cent renewables vision. "We are trying to address air pollution and global warming while, at the same time, providing energy security." These objectives, Jacobson stresses in an interview with American outlet Cnbc, distinguish his team's work from others, which are often focused solely on reducing greenhouse gas emissions.

The transition to cleaner energy grids could be completed by 2035, he says, provided that progress is made on the energy efficiency front — meaning savings and more mindful use of energy across various sectors — and that 80 per cent of the work will be completed within the next decade.

Progress since 2009

Since 2009, Jacobson has been working on an approach based exclusively on renewables, and in 2017 he co-authored, together with progressive political candidate Bernie Sanders, a piece published in British daily The Guardian focused on the use of clean energy. Another milestone: in 2015 he published an energy roadmap covering all 50 US states.

That latest work has been revised and improved by taking several factors into account. First and foremost, the professor and his team gained access to highly precise data, previously unavailable, on the heat required to warm homes across the United States. They also decided to focus on the use of batteries to make the grid more stable and capable of meeting peak demand, eliminating the option — which had proved impractical and lacking in political support — of adding turbines to hydroelectric plants to increase their output.

A more stable and smooth energy supply

When the sun isn't shining or the wind isn't blowing, the use of batteries with a four-hour capacity can compensate for the intermittency of renewable sources and make the grid more stable and reliable, the professor stresses. This is provided they are used simultaneously, discharged sequentially, and that one storage device takes over should another fail to meet energy demand. This solution has been devised by the research team to avoid the use of ultra-long-duration storage devices, which are not yet available on the market.

Another cornerstone for making a grid stable and clean is planning. It is true that wind and sun are variable, but it is equally true that "if the wind isn't blowing in one place, it's usually blowing somewhere else. So over a very large area, you can have a smoother supply of energy," Jacobson asserts confidently. And while wind and sun are free, hydroelectric power "is a perfect backup, because you can turn it on and off instantly."

In the researchers' vision, the roadmap requires prices that incentivise consumers to carry out energy-intensive activities during peak production hours. "Demand response is a major component for making the grid stable," the professor adds. "Today it is used to some extent, although in many areas of the United States the price of electricity is constant throughout the day… and that is a problem."

Mark Z. Jacobson ✓ @mzjacobson

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What's terrific and necessary is the 5.1 GW of batteries, (11% of the growth)

And unlikely both if either nuclear reactors will come online in 2022

Solar Will Account For Nearly Half Of New US Electric Generating Capacity In 2022 cleantechnica.com/2022/01/10/sol… @Cleantechnica @ElonMusk

♥ 58💬 15 11 gen 2022 · Apri su X →

The results of the simulations

So far, Jacobson and his team have conducted simulations in Alaska, Hawaii, California, Texas, New York and Florida and in a grouping comprising 48 states (approximations have been made for the remaining ones). They focused in particular on Texas, afflicted by blackouts throughout 2021, and California, which frequently lost power during the summer of 2020.

Three models were used:

1. the first involves comparing the energy produced today in each sector of each of the 50 states with that obtained from wind, water and sun;
2. the second uses a meteorological model to make the most accurate possible forecasts of wind and solar energy produced across all states;
3. the third and final component cross-references energy demand for 2050 with the meteorological model.

The percentage of renewables for California and Texas by 2050

Beyond technologies that have recently seemed to attract greater government and private interest, such as next-generation nuclear power plants, and beyond concerns about the long commercialisation timelines for more innovative devices such as ultra-long-duration batteries, Jacobson insists that the greatest difficulty lies in information. Not everyone is aware of what is already possible today; work must be done to increase collective awareness and knowledge about the realisation of this possible future.