Ken Caldeira on What To Do

Famous climate scientist Ken Caldeira has a new article out:

• Ken Caldeira, Stop Emissions!, Technology Review, January/February 2016, 41–43.

Let me quote a bit:

Many years ago, I protested at the gates of a nuclear power plant. For a long time, I believed it would be easy to get energy from biomass, wind, and solar. Small is beautiful. Distributed power, not centralized.

I wish I could still believe that.

My thinking changed when I worked with Marty Hoffert of New York University on research that was first published in Nature in 1998. It was the first peer-reviewed study that examined the amount of near-zero-emission energy we would need in order to solve the climate problem. Unfortunately, our conclusions still hold. We need massive deployment of affordable and dependable near-zero-emission energy, and we need a major research and development program to develop better energy and transportation systems.

It’s true that wind and solar power have been getting much more attractive in recent years. Both have gotten significantly cheaper. Even so, neither wind nor solar is dependable enough, and batteries do not yet exist that can store enough energy at affordable prices to get a modern industrial society through those times when the wind is not blowing and the sun is not shining.

Recent analyses suggest that wind and solar power, connected by a continental-scale electric grid and using natural-gas power plants to provide backup, could reduce greenhouse-gas emissions from electricity production by about two-thirds. But generating electricity is responsible for only about one-third of total global carbon dioxide emissions, which are increasing by more than 2 percent a year. So even if we had this better electric sector tomorrow, within a decade or two emissions would be back where they are today.

We need to bring much, much more to bear on the climate problem. It can’t be solved unless it is addressed as seriously as we address national security. The politicians who go to the Paris Climate Conference are making commitments that fall far short of what would be needed to substantially reduce climate risk.

Daunting math

Four weeks ago, a hurricane-strength cyclone smashed into Yemen, in the Arabian Peninsula, for the first time in recorded history. Also this fall, a hurricane with the most powerful winds ever measured slammed into the Pacific coast of Mexico.

Unusually intense storms such as these are a predicted consequence of global warming, as are longer heat waves and droughts and many other negative weather-related events that we can expect to become more commonplace. Already, in the middle latitudes of the Northern Hemisphere, average temperatures are increasing at a rate that is equivalent to moving south about 10 meters (30 feet) each day. This rate is about 100 times faster than most climate change that we can observe in the geologic record, and it gravely threatens biodiversity in many parts of the world. We are already losing about two coral reefs each week, largely as a direct consequence of our greenhouse-gas emissions.

Recently, my colleagues and I studied what will happen in the long term if we continue pulling fossil carbon out of the ground and releasing it into the atmosphere. We found that it would take many thousands of years for the planet to recover from this insult. If we burn all available fossil-fuel resources and dump the resulting carbon dioxide waste in the sky, we can expect global average temperatures to be 9 °C (15 °F) warmer than today even 10,000 years into the future. We can expect sea levels to be about 60 meters (200 feet) higher than today. In much of the tropics, it is possible that mammals (including us) would not be able to survive outdoors in the daytime heat. Thus, it is essential to our long-term well-being that fossil-fuel carbon does not go into our atmosphere.

If we want to reduce the threat of climate change in the near future, there are actions to take now: reduce emissions of short-lived pollutants such as black carbon, cut emissions of methane from natural-gas fields and landfills, and so on. We need to slow and then reverse deforestation, adopt electric cars, and build solar, wind, and nuclear plants.

But while existing technologies can start us down the path, they can’t get us to our goal. Most analysts believe we should decarbonize electricity generation and use electricity for transportation, industry, and even home heating. (Using electricity for heating is wildly inefficient, but there may be no better solution in a carbon-constrained world.) This would require a system of electricity generation several times larger than the one we have now. Can we really use existing technology to scale up our system so dramatically while markedly reducing emissions from that sector?

Solar power is the only energy source that we know can power civilization indefinitely. Unfortunately, we do not have global-scale electricity grids that could wheel solar energy from day to night. At the scale of the regional electric grid, we do not have batteries that can balance daytime electricity generation with nighttime demand.

We should do what we know how to do. But all the while, we need to be thinking about what we don’t know how to do. We need to find better ways to generate, store, and transmit electricity. We also need better zero-carbon fuels for the parts of the economy that can’t be electrified. And most important, perhaps, we need better ways of using energy.

Energy is a means, not an end. We don’t want energy so much as we want what it makes possible: transportation, entertainment, shelter, and nutrition. Given United Nations estimates that the world will have at least 11 billion people by the end of this century (50 percent more than today), and given that we can expect developing economies to grow rapidly, demand for services that require energy is likely to increase by a factor of 10 or more over the next century. If we want to stabilize the climate, we need to reduce total emissions from today’s level by a factor of 10. Put another way, if we want to destroy neither our environment nor our economy, we need to reduce the emissions per energy service provided by a factor of 100. This requires something of an energy miracle.

The essay continues.

Near the end, he writes “despite all these reasons for despair, I’m hopeful”. He is hopeful that a collective change of heart is underway that will enable humanity to solve this problem. But he doesn’t claim to know any workable solution to the problem. In fact, he mostly list reasons why various possible solutions won’t be enough.

25 Responses to Ken Caldeira on What To Do

  1. Pity his views on solar, wind, and batteries are 10 years out of date and incorrect.

    • John Baez says:

      It would be great if you can provide some evidence that his views are incorrect. Claims without evidence are only convincing to those who are already predisposed to agree. Admittedly, Caldeira’s piece suffers from this very problem.

      • Darin Caggiano says:

        I wouldn’t say incorrect, but he made some very strong statements. Graham and Greg have good points about the efficiency of heating with electricity and inefficient energy use associated with modern building design. I think this statement suggests his views on the costs of battery storage and solar power are dated.

        Even so, neither wind nor solar is dependable enough, and batteries do not yet exist that can store enough energy at affordable prices to get a modern industrial society through those times when the wind is not blowing and the sun is not shining.

        Tesla’s powerwall has brought the cost of warrantied energy storage down to ~10+c/kWh, and utility scale solar is below 6c/kWh without subsidies. That’s more expensive than the US average if we store every kWh we use, but it’s less expensive if we only store half of what we use.

        I agree with the need to build a renewable grid, vastly improve energy use in buildings, and electrify transportation, but I don’t see how that translates to a system of electricity generation that’s several times larger.

        Most analysts believe we should decarbonize electricity generation and use electricity for transportation, industry, and even home heating. (Using electricity for heating is wildly inefficient, but there may be no better solution in a carbon-constrained world.) This would require a system of electricity generation several times larger than the one we have now.

        35kWh of electricity from solar panels would take most EVs 100+ miles, but 35kWh of gasoline only takes a Prius 50+ miles, and to get that 35kWh of gasoline, we need to use 2-5kWh of coal, natural gas, and electricity.

        I’m not saying we don’t need to make huge steps in how we generate and use energy, but I also think it’s important for us to accurately represent the challenges ahead.

  2. ?? He does mention nuclear: After the NOAA graph, the paragraph concludes “build solar, wind and nuclear plants.”

  3. Tiny Tiger says:

    Dear Mr. Baez, it could be because of the FMEA for each. The one for nuclear power is awful. Ask the Japanese! Once you factor in the neglect, malice and ignorance that we are capable of, a massive-scale energy strategy needs to be VERY fool-proof and the failure modes “recoverable”…

    • John Baez says:

      I guess you’re answering this question in my blog article: “Why doesn’t Caldeira discuss nuclear power?” As Ian pointed out, he does mention nuclear power as part of the solution… so I deleted my question.

  4. nad says:

    My thinking changed when I worked with Marty Hoffert of New York University on research that was first published in Nature in 1998. It was the first peer-reviewed study that examined the amount of near-zero-emission energy we would need in order to solve the climate problem. Unfortunately, our conclusions still hold.

    I had only browsed that article but it seems he article consists mainly of computations of amounts of zero-carbon energy needs, but concerning the feasibility of non-nuclear renewables one only finds sentences like this and links to other articles:

    There are no energy systems technologically ready at present to produce the required amounts of carbon-free power.[6]

    and if I have not overlooked something it seems here are no other justifications for the latter assertion.

    • John Baez says:

      Good point. I will look at his reference to article [6], but there should be more recent studies of this issue. It’s hard to believe Caldeira is solely relying on work from before 1998… but you’re right, he’s not doing much in his new short article to prove his claims to skeptical readers.

      Just for fun, here is a graph from his 1998 paper:

      Figure 2 Fossil-fuel carbon emissions and primary power in the twenty-first century for IS92a and WRE stabilization scenarios. a, Carbon emissions; b, primary power and c, carbon-free primary power. Coloured areas are gas, oil, coal, nuclear and renewable components of IS92a from the energy economics model of Pepper et al. Carbon emissions for WRE scenarisos are outputs of our inverse carbon-cycle model. Fossil-fuel power for WRE sceneros is based on IS92a burn rates of gas,ad and coal employed sequentially in descending priority and limited by total carbon emission caps. Carbon-free primary power is total primary power less fossil-fuel carbon power

      • Walter Blackstock says:

        To me Caldeira’s essay is more like a press release, not a learned peer-reviewed paper, so maybe you are being over-critical.

        • John Baez says:

          It’s just a kind of ‘column’ or ‘opinion piece’ in the Technology Review. So yeah, it won’t have references. But it gains its credibility from the fact that Ken Caldeira is one of the most famous climate scientists thinking about global warming. So, if he says the conclusions of his 1998 Nature piece still hold, one would like to see some evidence—if not here, somewhere—that this is true.

          Of course it’s also worth reading that 1998 Nature piece, to see what the conclusions actually were!

        • Darin Caggiano says:

          It looks like he accurately predicted both the increase in Carbon emissions and the decrease in emissions intensity of energy over the past 15+ years, but at the same time he overestimated the energy required to reach a particular level of economic activity, which seems consistent with the views he expressed in his editorial.

          While it’s inaccurate, I don’t see any harm in overestimating how much renewable capacity we need to hit a given level of Carbon emissions. We probably need ten times more renewable generation to get our long run emissions into the 350ppm to 450ppm region.

  5. Graham says:

    Ken Caldeira says

    Using electricity for heating is wildly inefficient, but there may be no better solution in a carbon-constrained world.

    David MacKay in “Sustainable Energy — without the hot air” (2009) says

    Nay-sayers object that the coefficient of performance of air-source heat pumps is lousy – just 2 or 3. But their information is out of date. If we are careful to buy top-of-the-line heat pumps, we can do much better. The Japanese government legislated a decade-long efficiency drive that has greatly improved the performance of air-conditioners; thanks to this drive, there are now air-source heat pumps with a coefficient of performance of 4.9; these heat pumps can make hot water as well as hot air.

    • Greg Wellman says:

      I came to post much the same same thing about coefficient of performance. Also, better insulation – the typical North American home loses several times more heat than it would if it was better designed/constructed.

  6. Jenny Meyer says:

    The previous discussion of whether solar and wind were developing more rapidly than anticipated had me wondering what ever happened to the nuclear energy component of a carbon-free energy future. Had it become too expensive for anyone to want to invest in it? I found this article:

    The parts of this article that I can actually understand suggest that smaller nuclear power reactors could be mass-produced and modular, which would make them relatively cheap. Passive safety designs would make them safe to operate in places that don’t have the necessary human cultural institutions to operate a large nuclear reactor safely, which — I think — is at the heart of a lot of objections to nuclear power right now, and rightly so.

    Apparently some large companies in the nuclear industry were looking at this small nuke model not very long ago, but dropped the project because the financial aspects weren’t making sense. The time for payback on investment wasn’t attractive.

    Figuring in the costs of climate-driven natural disasters might make small nukes seem a lot more attractive! Maybe government subsidies currently at Big Oil carbon could be redirected toward the small nuke industry instead?

  7. domenico says:

    I think that a computer like Watson, or a good big data processing, can to search to optimize the energy production of the Earth, looking trend of processes ,and investments, and economic policies more productive: this can help the world politics to make the right choices.
    There are many small improvements that can give a reduction of carbon emission, and the nuclear power could be not the long-term best solution, if there are too constraints.

  8. Plod On says:

    In today’s news at, an article about a new study from NOAA that addresses the issues of large-scale renewable electrical energy production and transmission quite positively:

    “The study used a sophisticated mathematical model to evaluate future cost, demand, generation and transmission scenarios. It found that with improvements in transmission infrastructure, weather-driven renewable resources could supply most of the nation’s electricity at costs similar to today’s.

    “Our research shows a transition to a reliable, low-carbon, electrical generation and transmission system can be accomplished with commercially available technology and within 15 years,” said Alexander MacDonald, co-lead author and recently retired director of NOAA’s Earth System Research Laboratory (ESRL) in Boulder.

    The paper is published online today in the journal Nature Climate Change.” DOI: 10.1038/NCLIMATE2921

    Apparently, “the key to resolving the dilemma of intermittent renewable generation might be to scale up the renewable energy generation system to match the scale of weather systems.”

    And certainly in complement, as another commenter has pointed out, we have marked and steady improvements in solar cells, flow batteries and so on.

    Any solutions, it seems, must be technological and political.

  9. Re the global grid concept. Here is a great starting place:

    “The Global Grid” Spyros Chatzivasileiadis, Renewable Energy.

    On some of the challenges we would face in doing this, just a sample,

    I have been looking into setting up a Motif investment with the global grid as the motif. But unlike some other technologies you would be able to invest in, there is no public company today that lists this as its mission. That should give you some idea of where this technology is at: very much in the dream stage.

  10. While I very much sympathize, given that the UNFCCC and IPCC processes have, pretty much behind the scenes, reconciled their lofty goals of holding temperatures to no more than +1.5C to +2C above preindustrial with willingness to cut emissions by embarking upon an implicit program of massive geoengineering, there are a couple of points with which I disagree.

    First, a specific one: Caldeira’s parenthetic remark, that “Using electricity for heating is wildly inefficient, but there may be no better solution in a carbon-constrained world”, is misleading at best, and incorrect at worst. A Fujitsu “Halcyon” air heat pump (others are made by Mitsubishi and GE) is very efficient in terms of electricity-based heating (and cooling!). I know from personal experience, last winter, where, despite the deep and cold winter, our units beat, in price, the costs of oil heating with forced hot water heating elements, and did it by 20%, despite operating at near the limits of the heat pumps’ operational range, and including a cost penalty for our purchasing our electrical energy locally entirely from New England Wind sources.

    Second, in the same way that exponential growth can be destructive for a world which needs to find ways of sustainable growth, I believe there are ways of jiggering business and economics which could put zero Carbon energy sources on an exponential growth path. Once that is done, anything is achievable within decades, if the exponential coefficient is adjusted correctly. The point is, in my personal opinion, we need to stop thinking of the public as a bunch of free will individuals and, instead, in the way advertisers do, as a body of people who have buttons to be pushed, and can be motivated to do things, with dynamics governed by equations like the rest of Nature. With ordinary things, even security things, do that would give me pause. Doing it for the existential risks to civilization that climate disruption poses is no problem for me.

  11. HG,

    your second point is an excellent one. I work in product development, and the last thing we compete on, in fact you thing you never want to compete on is price. While it is true that the market for energy is not the same as the market for watches, say, where you can raise the price of a good and increase sales (ah, Rolex, we in product development bow to your genius) it is equally true that the the energy market is not immune to our collective desires.

    Price is certainly an important factor in the energy market, but it is not the only determinant.

    Here is a thought experiment. You are given the choice between buying a house that has 30k$ worth of solar panels on the roof and 10k$ worth of kitchen cabinets, or 40k$ worth of custom cabinets? Clearly, if we were pressing more of those buttons you mentionl, we might see more folks making the 30/10 choice.

    I understand that marketing wont get me driving a hover car, but it seems to do a great job of putting people in SUV’s in lieu of more cost effective solutions.

    In the end the energy system we get will be the energy system we want.

  12. Thanks, Rob. Coincidentally, there is a new report from NOAA ESRL and CIRES out today, Rapid, affordable energy transformation possible, published in Nature Climate Change (paywall, unfortunately). Like the work by Jacobson and colleagues, this model envisages networks of solar and land-based wind energy that’s collected and allocated by a grid that spans the scale of meteorological systems. Indeed, I learned of it in a news item which appeared in a newsletter from the American Meteorological Society.

    • John Baez says:

      The main problem with the plan of Jacobson and Delucchi is that it doesn’t touch on many practical issues. You can see a summary and critique here:

      A path to sustainable energy, Azimuth Wiki.

      Also, they claim that nuclear power results in up to 25 times more carbon emissions than wind energy… but when you drill down into their calculations (which requires going back to an older paper by Jacobson), they assume that using nuclear power may ultimately cause a war in which fifty 15-kiloton nuclear devices are used, setting cities afire, giving CO2 emissions of 92–690 teragrams. Their upper limit on carbon emissions for nuclear power assumes the probability of such a war is 100% and the 690 teragrams of carbon are emitted. And they implicitly assume the probability of such a war is 0% if we don’t use nuclear power!

      The main problem here is that they don’t mention this assumption in their later papers.

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