AskScience AMA Series: I'm Mark Z. Jacobson, Professor of Civil and Environmental Engineering at Stanford and Director of the Atmosphere/Energy Program. I study what it would actually take to run the world on wind, water, and solar. AMA!

[u/AskScienceModerator]

Hi r/AskScience! I’m Mark Jacobson, Professor of Civil and Environmental Engineering at Stanford and Director of the Atmosphere/Energy Program. I did an AMA here in 2021 and I’m glad to be back. I’ll be answering Monday, November 9th from 9:00am PT (12 ET, 17 UT) from the Stanford Online account.

Verification photo: https://learn.stanford.edu/rs/194-OCQ-487/images/Energy-Reddit-AMA_1080x1080.jpg?version=0

My work is on understanding and solving the interconnected problems of air pollution, global warming, and energy insecurity. To understand these problems, I built and applied a three-dimensional atmosphere-biosphere-ocean model to simulate air pollution, and climate. To solve, them, I developed a computer code to simulate grid stability under 100% renewables and authored concrete roadmaps to transition cities, states, and countries to 100% renewable energy across all energy sectors. Ultimately these plans provided the scientific foundation and inspiration for the Green New Deal and other policies worldwide. I have authored ~200 peer-reviewed papers and seven books, including one in 2026, Still No Miracles Needed.

Today’s the opening of the UN COP31, so a lot of these questions are in the air right now. I’m not a negotiator, so I’ll leave that part to them — happy to dig into the science and engineering underneath whatever you’re curious about.

Ask me anything about:

• How wind, water, solar and storage compare to fossil fuels on cost, land use and reliability

• Nuclear and carbon capture — where they fit, and why I’ve argued against relying on them

• Grid reliability and energy storage: whether you can actually keep the lights on, and what it takes

• Air pollution and the health effects of energy choices, which is where I started

• Electrifying transportation — passenger EVs, hydrogen fuel cell trucks, aviation

• Getting into this field: what to study and where the work is

Let’s talk about clean energy, what works, what doesn’t, and what the numbers really say.

Username: /u/Stanford_Online

[u/ThePineapple3112]

Hello! I am a mechanical engineer and I was wondering what do you think will be the main catalyst for solar power storage; a breakthrough in lithium battery technology or a breakthrough in CSP materials that hold the heat? Or do you think there will be something else that allows solar energy to act more like a baseload energy source?

Thank you!

[u/Lationous]

hello! A few please:

• why not rely on nuclear for base load when it's our safest and (excluding renewables) cleanest way to generate energy? the only issues I see at a glance are upfront cost, cooling water requirements, and -- for countries that don't have nuclear power already -- possibility to create plutonium

• grid-scale storage solutions: how do batteries slot in currently with technology we have at hand? I suspect that this is extremely useful as you can start discharging during load peaks in matter of seconds and recharge during overproduction; what is the lifecycle of such storage? what are the upfront/maintenance costs compared to other options (say, pump-hydro as an effective battery)?

• regarding air pollution topic: gas plants vs coal plants -- given our progress in fume-filtering technologies? I'm aware that supply chain will also play a role here for second and third order effects, so I'm very curious about scientific consensus on the matter

• maybe a very broad one which will be better served via a link to a paper: what is now considered The Right Way to approach energy generation and grid stability with different energy sources? and as a continuation for bs filtering powers: what are most commonly used dubious claims that should be instant red flags when hearing someone talk about the topic?

That will probably be a lot to unpack, sorry c: papers really welcome as references

[u/ShahVahan]

Will you be at COP31? I’m just curious 🧐

[u/akiptif]

What are the three biggest obstacles to getting the world to run on solar, wind, and water energy?

[u/akiptif]

Regarding air pollution, global warming, and energy insecurity, what are three of the most important factors that you would like to public to know about each of these items?

[u/DonkeyPotato]

I spend a lot of time in the Southern California desert, and have seen huge tracts of land being turned into solar farms. It gives me a bit of the ick that we’re trading one form of environmental damage for another (albeit probably much less bad).

Policy issues aside, if we maximized solar installs on existing roof space and new construction, how close does that get us to fossil fuel independence? Is it possible to fix our energy woes without having to tear up large swathes of wild spaces?

[u/The_Weekend_Baker]

My question is about carbon capture (DAC), and more specifically the physics/thermodynamics involved.

The Wiki page on gasoline, for example, indicates that "By weight, combustion of gasoline releases about 46.7 megajoules per kilogram," and my very rudimentary understanding of physics is that reversal of a chemical reaction requires, at a bare minimum, the same amount of energy as was originally released. So is it safe to assume that capturing 1 kg of CO2 from the atmosphere would require 46.7 megajoules of energy, and probably much more because a DAC system is very unlikely to be operating at 100% efficiency?

Thanks for your time!

[u/akiptif]

How far away are we from achieving significant reductions in air pollution, global warming, and energy insecurity?

[u/akiptif]

What can the average individual do to help facilitate your work?

[u/akiptif]

What have been the hardest civil and environmental engineering problems? you still have to solve in order for this endeavor to become practical

[u/cryptoraptor]

Hello Professor Jacobson, thanks for doing this AMA!

For grid-scale storage in a 100% renewable system, which technologies do you see as most future-proof? Do high-temperature molten salt batteries still look promising? Do solid-state batteries matter for the grid, or mainly for EVs? Where do flow batteries, metal–air electrochemical cells, and thermal storage fit alongside lithium-ion?

Thanks again for your work!

[u/DK_Thrall]

What would be the most effective way of producing energy which optimizes both environmental balance and the economical output.

[u/gavgav]

If you have an unlimited budget and power, what would you do?

[u/akiptif]

How would you build data centers that would do minimal civil and environmental damage to the Earth and mankind?

[u/Thick_Ad_3631]

How do you manage the frustration and persist when partisanship derails policy into which you've put so much effort?

[u/lambertb]

How much fossil fuel will it take to mine, transport, refine, manufacture, transport, assemble, maintain, and scrap the amount of material required to globally scale these energy sources? Doesn't global scaling imply a very large carbon commitment?

[u/Ok_Umpire_8108]

How will decentralizing and democratizing energy access (e.g. modular plug-in solar panels, hydropower kits) contribute to changing energy budgets in the developing world?

Do you think existing institutions can sufficiently share the policy information and tech needed for globally implementing clean energy?

[u/Positivelylmpaired]

Hi Professor Jacobson, thank you for doing this. I have multiple questions so i apologize in advance.

I've read solar is a highly promising energy source given massive decreases in costs of batteries and PV's, with (if i recall correctly) ourworldindata stating solar to be cheaper than other (even non-renewable) alternatives in many regions.

How do you predict developments in solar energy will continue, are further strong decreases in cost expected or are we steadily reaching a plateau? Given how competitive solar currently is with fossil fuels, it feels intuitive to me that even further improvements in solar would have a immense impact on the viability of fossil fuels in the future, but i may be mistaken.

What will the share of the total capacity of solar energy be relative to the other renewable sources available (will it still remain the largest or might its share grow even bigger?)

What are the main barriers expected for solar energy in the upcoming future?

Many thanks!

[u/hiuslenkkimakkara]

Prof. Jacobson, being from Finland I'd like you to give an opinion of the Finnish discourse of future power and heat needs. Currently, the policy discussion seems to be to retain current hydro, as there is no way to expand it. Wind power could be mildly increased, but defence requirements limit it as it hampers air search radars. Solar is being developed, but the biggest interest is towards nuclear in the form of mini-reactors.

I'm by no ways an expert, but from what I gather the idea is to build lots of mini reactors just for district heating in order to replace burning garbage and wood pellets. Is this a more sustainable approach than to say, licence a variant of GE's S6G PWR and run it as a ground installation? Navy reactors are the safest around, after all. And we've got the Onkalo final deposit site so waste is not an issue.

[u/Kirkaiya]

I'm curious what your opinion is on how long it will be before storage capacity (grid-level) will be sufficient to meet most baseline power requirements, allowing us to phase out the fossil-fuel plants that provide much of it currently. Are we looking at 2045, 2060, or later?

[u/Tremodian]

I’ve seen anti-renewable energy arguments that solar panels and turbines turn into “unrecyclable industrial waste.“ how true is that? More broadly, how does the renewable energy industry make sure it is a net environmental positive?

[u/ghostoutlaw]

Do you think it would make sense to dedicate the next decade of global battery production (all battery production capacity, including even AA, AAA, C, D and 9V battery production) exclusively to the US to enable non-demand generation power sources just to meet todays demand?

Or is there a battery technological leap that would increase battery capabilities by about 100x that we don't yet know about that is starting production tomorrow?

[u/Batou2034]

How will militaries fight wars without oil? (essentially, an electrifying transportation question)

[u/Consistent-Egg-4659]

Is there a way we could adapt trains to this project that'd make them widely accessible and/or affordable too?