Imagine trying to compare the value of sunlight, a barrel of oil, and the labor of a human worker. Traditional economics uses money, and traditional science uses simple energy (joules). The ecologist and systems thinker Howard T. Odum created a concept to unify these values: Emergy (spelled with an ‘m’).
Emergy is a core concept of General Systems Theory (GST). It is a powerful way to measure the true, total environmental cost of making a product or providing a service. Emergy argues that resources are not just valuable for the energy they contain now, but for the quality and amount of energy required to create them in the first place.
What is Emergy? The Stored Energy of the Past
The word Emergy stands for “embodied energy.” It is a measure of the energy used in the past to create what exists in the present. It moves beyond simple energy measurement to consider the history and quality of a resource.
Formal Definition
Emergy is defined as the total amount of energy of one kind (usually solar energy) that was directly or indirectly required to make a specific product or service.
- Past Cost: Emergy measures the energy that was “used up” in the transformations of nature and industry to produce a resource.
- Transformation: It recognizes that energy moves up a quality hierarchy. It takes much more energy to create a highly organized product (like a computer chip) than it does to create a low-quality product (like raw dirt).
Solar Equivalent Joules (sej)
To compare different resources, Odum had to create a single, standard unit. He chose to express all Emergy in Solar Equivalent Joules (sej).
- This process converts the energy contained in things like fossil fuels, clean water, and human labor back to the amount of sunlight energy originally required to produce them.
- By standardizing to sej, scientists can directly compare the true environmental cost of vastly different items, regardless of their market price.
Quality and the Emergy Hierarchy
The core idea of Emergy is that not all energy is equal. A unit of concentrated energy, like electricity, is much more valuable than a unit of dispersed energy, like sunlight.
Energy Quality and Transformity
The difference in energy quality is measured by transformity.
- Transformity is the ratio of the Emergy required to produce a resource to the useful energy the resource actually contains.
- The higher the transformity, the higher the quality of the energy. For example, the transformity of a fossil fuel is much higher than the transformity of the wind that helps produce it. This is because it took millions of years and complex geological processes (a high energy cost) to organize and concentrate that energy into oil.
The Energy Systems Approach
Emergy analysis is based on Odum’s Energy Systems approach, which uses the Maximum Power Principle. This principle suggests that systems that survive are those that maximize the capture and use of useful energy. Emergy helps determine what energy is truly useful in the long run by showing its real production cost.
Emergy (embodied energy) is the key concept that links environmental science to economics. By measuring the quality and history of energy inputs, it provides a scientific, non-monetary value for resources, revealing the true environmental burden required to sustain any system or product.
Emergy’s Application: True Value and Sustainability
Emergy is one of the most powerful tools created by General Systems Theory because it applies scientific laws to real-world problems.
Assessing True Value
Emergy analysis often shows a vast difference between an item’s monetary value and its Emergy value.
- Ecosystem services, like clean water production by a forest, may have a low market price (or no price at all), but they have an extremely high Emergy value because of the vast amount of solar energy and natural processes required to produce them.
- This distinction helps governments and planners understand that a healthy ecosystem represents enormous stored wealth that cannot be easily replaced by human technology.
Measuring Sustainability
Emergy is vital for measuring the long-term sustainability of any system, from a farm to a whole country.
- If an area is using resources (like imported fuels or materials) that have a much higher Emergy cost than the renewable Emergy it captures (like local sun and rain), the system is running at an Emergy deficit.
- This indicates the system is unsustainable, because it is consuming its environmental wealth at a rate that is too costly to maintain naturally.
Conclusion
Emergy is the essential measure of quality and history in the study of energy systems. By defining Emergy as the stored energy of one kind required for production, Howard T. Odum provided a universal, scientific metric. This concept allows scientists to transcend traditional monetary measures, revealing the true environmental cost and long-term sustainability of resources, services, and complex human systems, fulfilling a key goal of General Systems Theory.
