Challenges and interdisciplinary approaches

September 15, 2008 • Categories: Journal Series

By Frank Incropera


What kind of energy future would we like to see? Few would argue with continued access to abundant, low-cost energy supplies or elimination of energy as a barrier to economic development. We would probably also agree that supplies should be adequate to meet the basic needs of all humankind and accessible without geopolitical tensions or having to turn a blind eye to energy-rich but autocratic governments given to the abuse of human rights. And, finally, we would want energy to be used in an environmentally benign and sustainable manner. Regrettably, these conditions do not exist today, nor are they likely to be achieved any time soon.

Today, the world depends on nonrenewable fossil fuels for more than 80% of its primary energy. In the U.S., this dependence is close to 85%. However, new oil fields are becoming more difficult to find and develop, and within two decades the same will be said for natural gas. Global markets for these fuels are strongly influenced by geopolitical rivalries, and today’s investments in exploration may not yield meaningful supplies for a decade or more. At some point, conditions will be marked by scarcity, first of oil and later natural gas.

Abundant coal in nations with large appetites for energy insures use of this fuel throughout the 21st century. But, will it be used in an environmentally acceptable manner? Coal-fired power plants are the world’s largest source of carbon emissions. Technologies for capturing and sequestering the carbon have yet to be demonstrated, and even then it could be decades before implementation is widespread.

As we look beyond fossil fuels, we inevitably turn to renewable sources of energy, such as solar, wind, geothermal and biofuels, as well as to nuclear energy. Renewables must provide an increasing share of the world’s energy portfolio, but they are not without limitations and their contribution to global energy consumption is currently small, less than 1% for solar, wind and geothermal energy combined. Even with rapid growth, it could be many years before renewables have a significant effect, and the hope that they will one day meet all needs is not likely to be realized in this century. While today nuclear power contributes significantly to global demand for electricity, its future is clouded by concerns for disposal of waste materials.

So, where do we go from here? Do we turn to Washington for guidance? Unfortunately, for decades the nation has lacked any semblance of a comprehensive energy policy. While politicians are fond of rhetoric such as energy independence, partisanship, special interests and ideology have done little to improve the nation’s energy security. Meanwhile, dependence on energy imports continues to grow, contributing greatly to the nation’s burgeoning current account deficit and an unprecedented transfer of wealth to autocratic, if not hostile, nations.

So, what should be done? Well, for starters the nation needs a well defined road map, one having near and long term objectives that are executable and sensitive to both environmental and economic issues. Here are some suggestions.

The U.S. should set a firm goal, with specific implementation measures, to generate 25% of its electricity from renewables by 2025. It can be done. Denmark already generates 20% of its electricity from wind alone, and Germany is on track to generate as much from renewables by 2015. But, renewables aren’t enough, and although natural gas is gaining great favor in the halls of Congress, it would be a mistake to increase the use of gas-fired power plants or, for that matter, compressed natural gas vehicles. Yes, natural gas is a relatively clean fuel and yes the U.S. is experiencing resurgent gas production, but by increasing consumption we would embark on the same journey that led to our current dependence on imported oil. We don’t want to take that trip. So, what’s left?

Despite inherent environmental issues, the use of coal and nuclear energy for power production can’t be neglected. Coal is abundant and relatively inexpensive and, like it or not, it will be used. But, it must be used responsibly. The development of reliable and scalable technologies for capturing and permanently sequestering carbon dioxide should therefore be accelerated and ready for implementation by 2020. Until that time, no permits should be issued for the construction of new coal-fired power plants. The same can not be said for nuclear power plants.

Although there are fuel issues yet to be resolved, the time is at hand to increase the contribution of nuclear power to the nation’s supply of electricity. But, construction of new plants should be concurrent with transition from an open to a closed fuel cycle. That is, spent fuel rods should be reprocessed to increase the efficiency of fuel utilization and to reduce the amount of nuclear wastes that must be stored. To those who are opposed to nuclear power, yet are concerned about global warming, I would argue that, for the foreseeable future, increased use of nuclear power is essential if we are to reduce our greenhouse gas emissions.

And yes, the U.S. should continue to develop domestic sources of oil and gas, but mindful of the fact that our consumption of these fuels is excessively disproportionate to our remaining reserves. If the mood of the nation is to expand off-shore exploration for oil, so be it. But, let’s not delude ourselves. That oil will not provide short-term relief to prices at the pump, and long-term it will do little more than reduce the rate of declining domestic production. Excluding the long-term potential of shale oil, which has its unique problems, the U.S. is no longer among the oil rich nations of the world. So let’s keep drilling, but make no mistake. Regardless of the pace at which domestic sources are tapped, continued consumption at current levels will only exacerbate future dependence on imports, while diminishing domestic supplies available to future generations.

Enough said about energy supply. Let’s examine the demand side of the energy equation.
There is no dearth of suitable targets for reducing energy consumption by increasing energy efficiency, from appliances, lighting, computers and space heating/cooling systems to power plants, automated electricity distribution systems, automobiles and aircraft. More can be done in each of these categories, enabled by an ever present reservoir of human ingenuity. The automotive sector is an especially attractive target. The 2007 federal mandate of achieving a fleet average efficiency of 35 mpg by 2020 for light duty vehicles is hardly a stretch target. It is doable with today’s technologies. How about 45 mpg by 2020?

The U.S. should commit to achieving a one-third reduction in fossil fuel consumption for automotive transportation by 2025. The goal could be achieved by combining higher vehicle fuel efficiency standards with increased use of hybrid vehicles and biofuels derived from non food sources, as well as investments in modernizing and expanding public transportation systems.

Now, let’s address an issue that politicians are loathe to confront and one that may well subject me to an angry tirade. It’s the C-word, but I’m not referring to cancer. We Americans have become nothing short of reckless in our use of energy. If we are to successfully deal with our energy problems, we must adopt a mindset that values energy conservation. On average and at any instant, Americans consume energy at a rate of 12 kilowatts (kW), six times the global average and more than 20 times that of the world’s poorest nations. Yes, you might say, but look at the size of our economy. Even there we fair poorly, with energy consumption per GDP well above that of many nations.

In a 2004 book entitled The End of Oil, Paul Roberts attributes a substantial portion of the blame for the nation’s energy problems to the average American consumer, “who each year seems to know less, and care less, about how much energy he or she uses, where it comes from, or what its true costs are. Americans, it seems, suffer profoundly from what soon may be known as energy illiteracy: most of us understand so little about our energy economy that we have no idea that it has begun to fall apart.” Strong words, indeed. But even now with high gasoline prices and greater public concern, they retain an element of truth.

Can we become a 6 kW per person nation by 2025, recognizing that countries such as Germany and Japan are already below this level and may well be at 4 kW by then, while still maintaining vibrant, globally competitive economies? As a nation operating at 5 kW per person and aspiring to reach 2 kW, Switzerland provides a gold standard. They’re not likely to achieve such an ambitious goal, but it’s become part of the national psyche, and they will make progress.

When it comes to energy, time is a luxury that the U.S. can ill afford. It must begin to implement a suite of short- and long-term measures that make a difference and to do so with a sense of urgency. And, we must recognize that there is no silver bullet. All options must be embraced, including environmentally responsible use of fossil fuels and nuclear energy, as well as accelerated implementation of renewables and energy efficiency and conservation measures. Attention must be paid to both the supply and demand sides of the energy equation, maintaining adequate levels of the former and doing our best to reduce the latter. It could be argued that energy efficiency and conservation provide our most immediate and substantive sources of new energy.

Although the foregoing paragraphs have addressed energy in the context of domestic needs, it’s also important for Americans to think and act globally, particularly in managing relations with energy exporting nations and in responding to the needs of billions of people lacking access to the energy required for an acceptable standard of living. With a ten-fold or more difference in per capita energy consumption between developed and impoverished or developing nations, energy is clearly a differentiator between the haves and the have-nots, one that’s unacceptable as a permanent condition. Western nations have a responsibility to assist poorer nations in developing efficient and clean sources of energy that enable a transition from poverty. And, recognizing that climate change is likely to disproportionately affect the world’s poorest populations, high priority should be given by all nations to reducing greenhouse gas emissions.

Several years ago I read Thomas Cahill’s book on How the Irish Saved Civilization, and I was struck by an analogy that could be drawn. As a precursor to describing the transition of western civilization from the classical world to the medieval period, Cahill took a stab at delineating reasons for the fall of Rome, which ranged from “inner weakness” to “outer pressure.” In summary, however, he made an insightful characterization which may well apply to America’s treatment of energy issues over the past three decades. To quote Cahill: “What we can now say with confidence is that Rome fell gradually and that Romans for many decades scarcely noticed what was happening.” They simply didn’t see it coming, or perhaps if they had an inkling, they didn’t want to acknowledge it. Life was still too good.

The nation’s energy problems go well beyond the price of gasoline at the pump. They must be viewed more clearly and comprehensively, and as Americans, we must all be part of the solution.

Frank Incropera is Clifford and Evelyn Brosey Professor of Mechanical Engineering and former dean of Notre Dame’s College of Engineering. He teaches and conducts research on energy issues, including the role of public policy and geopolitical considerations.

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