Yuan-Tseh Lee

Chemistry of Global Climate Change

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Professor Yuan-Tseh Lee 李遠哲
President, Academia Sinica, Taiwan
Professor Emeritus, Department of Chemistry, UC Berkeley
Nobel Laureate, Chemistry 1986


The concerns of the environment do not lie solely with environmentalists and policy makers, but also with dedicated scientists. Our current understanding of the environment can be traced back to studies that were carried out more than 30 years ago. Professor Lee is a strong proponent for the development of a sustainable world.

Professor Lee is an alumnus of the University of California, Berkeley and was previously on the UC Berkeley faculty in the Department of Chemistry. Together with Dudley Herschbach and John Polanyi, he received a Nobel Prize in Chemistry in 1986 for their studies on the dynamics of fundamental chemical processes. In 1994, Professor Lee left for Taipei where he is now the president of Academia Sinica, the highest academic institution in Taiwan.

Frank Ling (FL) talks to Yuan-Tseh Lee (YTL) about the chemistry of the atmosphere, his concerns for developing a sustainable world and his experiences. Below is an edited transcipt.

FL: Professor Lee, thank you for joining us today.

YTL: Well, my pleasure.

FL: First of all, I would just like to say that I admire you very much for what you have done both as a scientist and as an educator. I understand these days you are interested in creating a sustainable society, one in which resources are used without harm to the environment or to people. When we talk about our atmosphere, there are two main issues that dominate: the depletion of the ozone layer caused by the release of refrigerants like chlorofluorocarbons and global warming due to increases in greenhouse gases like carbon dioxide. Well, with regard to the ozone layer, how are chemicals involved in destroying it.

YTL: About 30 years ago, one of the faculty members, Harold Johnston, worried about nitric oxide, but nitric oxide turned out not to be such a harmful gas. On the other hand, chlorofluorocarbons, especially when dissociated to produce chlorine atoms, will induce the chlorine cycle, which has been responsible for destroying the ozone layer. Around that time, in the 1970’s, the National Academy of Sciences organized a committee and looked at the problem of ozone layer destruction. Once they concluded that chlorofluorocarbon was the culprit, we instituted a policy to ban the use of chlorofluorocarbons and that has been quite effective. The ozone destruction, although it is still taking place, it is leveling off so there’s a chance in the next 20 years that the problem of chlorofluorocarbons might disappear.

FL: I think some recent studies suggest that the rate of destruction is slowing down. Some people even feel that the layer might be healed by the year 2050. Are you as optimistic?

YTL: Yes, if we really limit the usage of chlorofluorocarbons, then I will be very optimistic. But, I will still have to say that there are many countries producing large quantities of chlorofluorocarbons. Major industrialized countries are not using it anymore, but developing countries are using it so that also has to be stopped,

FL: Some alternatives have emerged for these CFCs, but they are not completely benign. Can you explain this a little bit?

YTL: Well, people try to replace one of the fluorine into hydrogen, so it will decompose by eliminating hydrogen chloride and hydrogen fluoride. Those are certainly better than chlorofluorocarbon, but not completely benign.

FL: In 1987, the Montreal Protocol was adopted to limit the use of ozone destroying compounds. Do you feel that this protocol has been successful and should it be modified in any way?

YTL: I think so. The protocol has been quite successful. Without the protocol, we will be in a much worse situation at present time,

FL: What about global warming? Can you describe how the greenhouse effect causes global climate change?

YTL: Yes, as you know, carbon dioxide, methane, chlorofluorocarbons will not absorb visible photons, they will absorb infrared photons. So when the sun irradiates the surface of the earth, visible photons will penetrate through but the radiation from the surface of the earth, which is typically 68 degrees Farenheit, emit infrared photons which will be absorbed by carbon dioxide, chlorofluorocarbons, or methane, And so, heat is trapped by the atmosphere and will not escape as efficiently. So when the carbon dioxide concentration increases, then the surface of the earth starts to warm up considerably.

FL: Clearly, these greenhouse gases are linked to our dependence on fossil fuels. There has been a lot of talk in developing and implementing renewable energy resources like wind, photovoltaics, and geothermal power, but so far they are very limited in their adoption. What do you think needs to be done technology-wise or policy-wise.

YTL: Well, as you know, the solar energy is enormous. In an hour, the sun is transmitting to the surface of the earth about the amount of the energy we use in an entire year of human society. So it means it takes an hour — the entire earth is receiving the amount of energy equivalent to the energy we use in an entire year. If we were to be a little bit more clever and learn how to use solar energy more efficiently, then we are going to go a long way without depending on the combustion of fossil fuel that produces carbon dioxide. And actually, during the last year or during the last eighteen months, there has been significant advances in the photovoltaic cell. In fact, with the silicon-based multi-layer component, the efficiency of converting the solar energy in electricity could be up to 35%, like those that have been done by Alferov (Nobel, Physics 2000) in Russia, but it turns out to be very expensive to make these silicon-based photovoltaic cells. So what Alferov has been doing is using solar collector reflected-light onto the small photovoltaic cell made out of silicon, but that is very expensive. And once you invest money, it takes more than 15 years to recover it and so economically, it is not very efficient, not very feasible. On the other hand, during the last 18 months, there has been a method using nanotechnology, using titanium dioxide as a base, dye-coated, dye-sensitized, so there is a device called dye-sensitized photovoltaic cell and that was invented by Grätzel in Switzerland. Efficiency can go up to 10% and a lot cheaper to make these photovoltaic cell. So we are on the eve of something new.

FL: Okay, there has been a lot of discussion on the hydrogen fuel economy and also to use fuel cells to store this hydrogen, how efficient and economical do you believe this is?

YTL: You see, when you talk about hydrogen economy, it is a mean to store the energy because the electricity could be stored in a battery or by splitting water into hydrogen and oxygen, or even if you run high temperature Breeder reactor, the energy could be used to split the water. So, sooner or later, we will be using hydrogen as a fuel. When we say we are moving to the hydrogen economy, it is when we stop using hydrocarbons (fossil fuels). Then, no matter how you collect the energy, whether nuclear or solar energy, probably the way to store energy will be in the form of hydrogen and oxygen. So using hydrogen to generate electrcity, the fuel cell certainly is the most efficient one. I do see that in the next 20 or 30 years, we will be moving to the hydrogen economy. It mean, so long as we learn how to use renewable energy and the renewable energy will come mainly from the sun, hydrogen will become an important player.

FL: The Kyoto Protocol was developed to limit these greenhouse gases but there has not been a lot of enthusiasm about it. Do you see it as a failure or just a bump in the road?

YTL: Well, I think it is a bump in the road. One of the reasons is that many countries, for example the United States: you see, we often say that 20th century is the century of the United States, but actually the 20th century is the century of the combustion of petroleum or the century of the petroleum industry. And the United States, the entire society, has developed by depending on the combustion of fossil fuel and one can not change so easily. It’s kind of sad that the global warming trend is continuing.

FL: Do you see any hope in reviving this protocol? Should it come in a different form perhaps?

YTL: During the last ten years, scientists are more and more convinced that global warming is real and will bring lots of damage to the global environment. So, the menace is there and people are starting to be aware of it. We can not neglect it anymore. In this sense, every country will face the global warming trend more seriously. At the same time, the research will be done to create renewable energy by wind power or might be even fusion. We always said that fusion will come along during the next 30 years, 30 to 40 years ago we’ve been saying that, but improvements have been made during the last 10 years. And the US is going to join the international collaboration that will include all the European countries, Japan, and the US to set up a fusion reactor and try to show one day it might be a practical source of energy.

FL: So there are certainly many countries involved in these efforts right now. What has Taiwan been doing in this regard?

YTL: The current government, the DPP, has been much more sensitive to the environment, so the government has been pushing for renewable energy, for photovoltaic cells or biomass or wind power. The renewable energy is still very small, so it still has a ways to go.

FL: On a global scale, the population is still increasing and certainly the demand for energy is rising. For example China, with its economic growth, has been consuming exponentially more energy and fuel each year. Some people even think this could be source of conflict in the future. Do you have any recommendations for their development?

YTL: Well, if you look back on the history of mankind, I would say that with the way human society developed during the 20th century, there is no future for us if we continue to go that way. You see, Western society has been moving up and improving the living condition using enormous amount of energy and natural resources. But the earth is limited, it is a finite earth in terms of providing natural resources or absorbing the waste we generate. So I remember 25 years ago when I first visited mainland China, I tried to remind them one should not try to imitate the way Western society developed because there is no future for the entire world. We have to find a much more efficient way to live. But, unfortunately if you look at the way Southeast Asia is developing, they are all imitating the way US has developed, using enormous amounts of energy and natural resources. And we have to wake up, that’s not the way to go.

FL: You are well known for being an optimist and seeing the potential for science to change the world for the better. Do you still feel hopeful that science and technology can offer these promises as they did 20 years ago or 50 years ago?

YTL: Certainly, not all the problems are scientific problems but a large fraction of problems we are facing today are science in nature. Although the current scientific knowledge and technology can not solve all the problems we are facing today — on the other hand if we keep on doing research and accumulating new knowledge — I do believe that a large fraction of those problems will be solved. That is why we are enormously enthusiastic about carrying out good research and educating the young generation of scientists so we can move many steps further.

FL: Are there any current developments that inspire you?

YTL: Well, as I said, the development of the photovoltaic cell gave me a new perspective on how the energy problem could be solved. One of the faculty members in the Department of Chemistry, Paul Alivisatos, is also using nanotechnology, using zinc selenide and those are embedded in polymers. And efficiency is not that high, up to 5 to 7%, and he is working together with a company in Japan trying to mass produce them more economically. Those developments will certainly bring us to a new step.

FL: I got a couple of last questions here specifically about your experiences. Looking back at the years, what accomplishments are you most proud of? Are there some stories you would like to share with us?

YTL: Well, one thing which really got me excited was that — when I was in Taiwan, very often I could not do the things I wanted to do maybe because the resources were not available or not enough people to discuss problems with — after I came here, I started to feel that nothing is impossible in America or nothing is impossible in California. So that gave me a great enthusiasm and excitement and it is your own effort which will allow you to attain something great scientifically. If you work hard, you might be able to do something nobody has been able to do. When I came here in 1962, that was the time people tried to visualize how chemical reactions take place. One can not see atoms or molecules with the naked eye, so we were devising new methods to see how can we understand chemical reactions takes place. I was enormously excited and I jumped into the field. After I got my degree in 1965, I started to work on ion molecule scattering and tried to visualize how chemical reactions take place from the measurement of velocity and angular distributions. So those were really critical periods of my scientific career. I learned a great deal here, I learned how to solve problems and learned many technical aspects of carrying out difficult experiments.

FL: I guess we are running out of time today. Are there any last words you would like to add about your work, Academia Sinica, or your hopes for the future?

YTL: Ten years ago, I went back to Taiwan, not because Taiwan is a wonderful place, they needed my help so I went back. During the last ten years, Academia Sinica has become a respectable scientific organization and I’m very happy that I’ve been able to help them but I still like it here though.

FL: Okay Professor Lee, I want to thank you for your time. Thanks for joining us today.

YTL: Well, my pleasure.

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