Sunday, April 22, 2007

Earth Day Thoughts

I drove my 4200 pound minivan around today while running errands. I feel really badly about that, especially because today is Earth Day. My mind wandered back to Daniel Nocera's talk at MIT on the Road, LA Edition, last month. I am posting some of his slides today, with his permission. Click on the pictures to view them in full detail. I put my own notes below each slide.

Slide 1: Our current global energy inventory is shown to the left. Nathan Lewis and Daniel Nocera performed some back of the envelope calculations to predict future energy needs using middling estimates for population growth, economic growth, and energy efficiency gains. (28 to 35 Terra Watts (TW) are a couple of reasonable rough estimates but the figure could be much, much more, unless we change our behavior drastically.) That leaves us with a big fat question mark for future energy sources.

Slide 2: I find this slide showing per capita energy demand in giga Joules (GJ) versus per capita GDP for a variety of nations especially embarrassing. It shows how much we produce per unit of energy. The lower left hand corner represents 3.2 billion of the world's 6.2 billion people. The box at lower right shows relative energy consumption per capita in units that I forgot to note down. If energy consumption per capita were distributed equally, the figure would be close to the current usage in Equatorial Guinea.

We lead the world in per capita energy consumption--by a lot. Equally rich industrial nations are much more frugal with their energy. See how the US's per capita energy consumption has been flat for two decades? It's only party due to gains in energy efficiency. It is largely because we stopped manufacturing things and now import so much of our industrial goods. I will blog about that later; in the mean time, you can read Goodie Bags and the Wealth of Nations.

Slide 3: Self Explanatory

Slide 4: Balanced Redox (reduction and oxidation) equations for the combustion of coal and methane, the main component of natural gas. Note that methane produces about twice as much energy per molecule of CO2 produced than coal. (A negative value means that energy is released.) Oil is largely composed of alkanes, chains of carbon with some hydrogens hanging off them, produces a middling amount of CO2 per unit of energy compared to coal and methane.

Slide 5: CO2 emission versus primary energy consumption per capita. This graph illustrates the types of fuel used by the nations. For instance, the US (indigo blue) uses mainly oil and gas with some coal. Japan (light cyan blue) uses a mixture of oil and coal. France (yellow) falls dramatically below other industrial nations because of their reliance on nuclear power.

Look at China and India in the lower left hand corner. They represent over one third of the world's population. If you want to be really scared, read this projection of world population from the International Institute for Applied Systems Analysis.

Slide 6: This is a popular graph of CO2 concentration versus time measured at the top of Mauna Loa, a volcano in Hawaii. The small zig zags demonstrate that the earth is a living, breathing entity. Plants absorb CO2 in the growing season. Because there is more land surface in the northern (boreal) hemisphere than in the southern one, there are slight depressions in CO2 concentrations each boreal summer. However, the overall trend is up. That means we are putting much more CO2 into the atmosphere than the planet can absorb.

Antarctic ice cores show us that the level of CO2 in the last 50 years is unprecedented in the past 650,000 years. Mixing times (the amount of time it takes to thoroughly mix a system) are shown below. It takes about 35 years to mix the atmosphere and the top layer of the ocean. It takes about 400-1000 years to mix the top layer of the ocean with the bottom layer.

Slide 13: I fast forwarded through all the pictures of retreating glaciers and coral bleaching. They are too depressing to show.

This slide shows that there is probably no way to get from here to there without letting go of my opposition to nuclear power. It also demonstrates that windmills will not be sufficient. However, solar power holds a great deal of promise. I have some professional experience with advanced photovoltaic technology and I agree with Professor Nocera. I also have some personal experience with low-tech solar hot water panels and I think almost everyone should have them.

What will the future look like? It largely depends upon our own collective behavior. Nocera says take a good look at Equatorial Guinea. I say, add some energy saving technology. Change some of our personal behavior. It could be a nice place to live.

But we have to act now. The longer we delay, the more bitter the medicine.

Note: The slides are from Daniel Nocera, but the notes are mine. I am responsible for all errors.


  1. I'm reading this now (10 years after you wrote it!) because I was curious to know what you think of nuclear power (as far as I can tell, you are the most intelligent and thoughtful person on the internet on topics that are interesting to me). Have your thoughts on nuclear energy changed/evolved?

    1. I shared the opinion of many scientists that nuclear power has killed many fewer people than coal. Each year, coal kills so many people in so many ways from mining to air pollution deaths. And then there is the huge amount of CO2 generated from burning coal.

      I think that nuclear power can be done relatively safely if we don't stint on $afety and use science, not politics, to site the reactors properly. I don't have much confidence in the current political and economic climate.

      But, yes, many scientists (myself included), believe that nuclear power has a place in helping us cool the planet.

    2. Thanks for the reply.

      I worked on basic research into photosynthesis in grad school. Finding a way to improve solar energy and crop efficiency was a stated motivation for a lot of our work when we wrote grants. But it is also pretty clear that there are a lot of issues with solar power (sunlight is diffuse and variable).

      I was not impressed with how nuclear power was discussed and dismissed by my advisor and others. Basically, the argument, as I understood it, was "nuclear is politically infeasible, so let's forget about it, and focus instead on solar (which isn't proven technology), and lobby for a carbon tax."

      I also think it's terrible that California is considering closing nuclear power plants early rather than fossil fuel plants.

    3. San Onofre was closed down after a botched retrofit.

      Diablo Canyon was shut down for myriad reasons, but being sited so close to several active earthquake faults is a very good reason.

      I am sad that, in the current political climate, no new ones with the latest safety equipment and better locations can be built. I really think that is an option that can help us reduce global warming.

  2. I thought that Diabolo Canyon is still operating, and there are plans to shut it down by 2025 (

    It's interesting to me that you think the risk of an accident from an earthquake is greater than the benefit from the clean energy that the plant produces. Presumably shutting down Diabolo Canyon will cause emissions to be higher than if a coal or natural gas plant was shut down in its place, but that is not a sufficiently compelling reason to keep it operating?

    1. Yes, I jumped the gun on the shuttering of Diablo Canyon.
      Aside: I visited Diablo and Forsmark in the 1970s and 1980s and got behind the scenes tours of both. (Complicated reasons and not blog fodder.)

      When nuclear power plants were cooled with ocean water, it made sense to put them on coastlines. Now that they use closed loop cooling systems, they can be located away from coastlines and rivers.

      I think that they should b/c coastlines are often either densely populated or on the border of two tectonic plates (earthquake risk.)

      Diablo Canyon is at the end of it's useful life anyway. So why not site the replacement in a less risky location?

  3. If I believed that Diablo canyon will be replaced with another (safer) nuclear power plant, I would not be upset about closing Diablo canyon early. But I think the political reality is that is not going to happen, and closing it early will cause carbon emissions from electricity generation to rise when we need them to fall. I would love to be wrong here.

    Thanks for the Forsmark link, it is fascinating.

    1. You are right that I don't think a nuclear power plant will open in CA any time soon. But, large-scale solar is becoming an important player.

      Also, residential roof-top solar is a very bad idea for reasons I will write an entire blog post about.

  4. I look forward to your blog post. I'm aware of the argument against roof top solar because it increases demand for air conditioning, which uses a large amount of electricity. I'm not aware of other reasons why roof top solar is bad.

    I'm happy that California has so much generation from solar power. But I'm skeptical that solar alone will be enough to curb carbon emissions as much as necessary because sunlight is intermittent and large-scale storage is challenging.

    AFAIK, solar PV and batteries are not environmentally benign. There are issues with mining and toxic waste disposal of used panels, and the impact on desert ecosysems. I'm willing to accept these negatives because I think they are better than burning fossil fuels and I don't want to live in a world without electricity, but I do see them as real concerns.

    *Aside: I also think there is a huge amount we as a state could do to improve how efficiently we use the power we generate. But that is a separate discussion.


Comments are open for recent posts, but require moderation for posts older than 14 days.