(14) Environmental Science


Sustainable Energy Choices for the 21st Century

Sustainable Consumption

How Can We Use Matter and Energy More Sustainably?

The second law of thermodynamics holds, I think, the supreme position among laws of nature. . . If your theory is found to be against the second law of thermodynamics, I can give you no hope.

Arthur S. Eddington

CONCEPT 2-5A The processes of life must conform to the law of conservation of matter and the two laws of thermodynamics.

CONCEPT 2-5B We can live more sustainably by using and wasting less matter and energy, recycling and reusing most matter resources, and controlling human population growth.

Today’s Advanced Industrialized Societies Waste Enormous Amounts of Matter and Energy

The processes of life must obey the law of conservation of matter and the two laws of thermodynamics (Concept 2-5A). We can use these physical laws to outline some ways for making a transition to more sustainable societies.

As a result of the law of conservation of matter and the second law of thermodynamics, using resources automatically adds some waste heat and waste matter to the environment. Most of today’s advanced industrialized countries have high-throughput (high-waste) economies that attempt to boost economic growth by increasing the flow of matter and energy resources through their economic systems.

These resources flow through their economies into planetary sinks (air, water, soil, and organisms), where pollutants and wastes can accumulate to harmful levels. What happens if more people continue to use and waste more energy and matter resources at an increasing rate? The law of conservation of matter and the two laws of thermodynamics tell us that this resource consumption will increasingly exceed the capacity of the environment to provide sufficient renewable resources, to dilute and degrade waste matter, and to absorb waste heat. This is already happening because of our large and growing ecological footprints.

We Can Shift to Matter-Recycling and Reuse Economies

A temporary solution to this problem is to convert a linear throughput economy into a circular matter recycling and reuse economy, which mimics nature by recycling and reusing most matter outputs instead of dumping them into the environment.

This involves applying another of the four scientific principles of sustainability. Although changing to a matter-recycling-and-reuse economy would buy some time, it would not allow ever more people to use ever more resources indefinitely, even if all matter resources were somehow perfectly recycled or reused. The two laws of thermodynamics tell us that recycling and reusing matter resources always requires using high-quality energy (which cannot be recycled) and adds waste heat to the environment.

The high-throughput economies of most developed countries rely on continually increasing the rates of energy and matter flow. This practice produces valuable goods and services, but it also converts high-quality matter and energy resources into waste, pollution, and low-quality heat.


A low-throughput economy, based on energy flow and matter recycling, works with nature to reduce the throughput and unnecessary waste of matter and energy resources. This is done by (1) reusing and recycling most nonrenewable matter resources, (2) using renewable resources no faster than they are replenished, (3) reducing resource waste by using matter and energy resources efficiently, (4) reducing unnecessary consumption, (5) emphasizing pollution prevention and waste reduction, and (6) controlling population growth to reduce the number of matter and energy consumers. Question: What are three ways in which your school or community could operate more like a low-throughput economy?

We Can Use Scientific Lessons from Nature to Shift to More Sustainable Societies

The three scientific laws governing matter and energy changes and the four scientific principles of sustainability suggest that the best long-term solution to our environmental and resource problems is to shift from an economy based on increasing matter and energy flow (throughput) to a more sustainable low-throughput (low-waste) economy. In other words, we can live more sustainably by using and wasting less matter and energy, recycling and reusing most matter resources, and controlling human population growth (Concept 2-5B).

The Hubbard Brook Experimental Forest and Sustainability

The controlled experiment discussed in the Core Case Study that opened this chapter revealed that clearing a mature forest degrades some of its natural capital. Specifically, the loss of trees and vegetation altered the ability of the forest to retain and recycle water and other critical plant nutrients-one of the four scientific principles of sustainability. In other words, the uncleared forest was a more sustainable system than a similar area of cleared forest.

This loss of vegetation also violated the other three scientific principles of sustainability. For example, the cleared forest had fewer plants that could use solar energy to produce food for animals. And the loss of plants and animals reduced the life-sustaining biodiversity of the cleared forest. This in turn reduced some of the interactions between different types of plants and animals that help control their populations.

Humans clear forests to grow food and build cities. The key question is, how far can we go in expanding our ecological footprints without threatening the quality of life for our own species and the other species that keep us alive and support our economies? To live more sustainably, we need to find and maintain a balance between preserving undisturbed natural systems and modifying others for our use.

Then next themes apply the three basic laws of matter and thermodynamics to living systems, and they explore some biological principles that can help us live more sustainably by understanding and learning from nature.

Review Questions:

1. What is science? Describe what a controlled scientific experiment is. Explain the steps involved in the scientific process.

2. What are three limitations of environmental science?

3. What is matter? Identify the two chemical forms of matter. Describe the building blocks of matter. What makes matter useful as a resource?

4. What is a physical change? What is a chemical change? Describe the three types of nuclear changes that matter can undergo.

5. Identify and discuss the scientific law that governs the changes of matter from one physical or chemical form to another.

6. What is energy? Describe the two major types of energy. Define the term energy quality and explain how it relates to the usefulness of energy as a resource.

7. Identify and define the two scientific laws that govern energy changes.

8. How are the scientific laws governing changes of matter and energy from one form to another related to resource use and environmental degradation?

9. What is a high-throughput economy? What is a low throughput economy?

10. How can a society move from a high-throughput economy to a more sustainable lower-throughput economy?


Critical Thinking

1. List three ways in which you could apply Concept 2-5B to making your lifestyle more environmentally sustainable.

2. What ecological lesson can we learn from the controlled experiment on the clearing of forests described in the Core Case Study that opened here? List two ways that you can apply this paper to your own lifestyle.

3. Respond to the following statements:

a. Scientists have not absolutely proven that anyone has ever died from smoking cigarettes.

b. The natural greenhouse theory-that certain gases (such as water vapor and carbon dioxide) warm the lower atmosphere-is not a reliable idea because it is just a scientific theory.

4. A tree grows and increases its mass. Explain why this phenomenon is not a violation of the law of conservation of matter.

5. If there is no “away” where organisms can get rid of their wastes, why is the world not filled with waste matter?

6. Someone wants you to invest money in an automobile engine that will produce more energy than the energy in the fuel used to run the motor. What is your response? Explain.

7. Use the second law of thermodynamics to explain why a barrel of oil can be used only once as a fuel, or in other words, why we cannot recycle energy.

8. a. Imagine you have the power to revoke the law of conservation of matter for one day. What are three things you would do with this power?

b. Imagine you have the power to violate the first law of thermodynamics for one day. What are three things you would do with this power?

9. What three changes could you make in your lifestyle to help implement the shift to a more sustainable, low-throughput society? Which, if any, of these changes do you plan to make?

10. List two questions that you would like to have answered as a result of reading these last themes.

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