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Chapter 14: Problem 11

Our modern food industry has an EROEI of 0.1:1. In pre-industrial settings, when energy investment for food production was in the form of muscle power (animal and human), why would a 0.1:1 EROEI for food have been untenable? Next, describe the conditions for an exact break-even food EROEI of 1:1. What would this mean in terms of where effort/energy goes? What would this leave for building shelters, cathedrals, or esthetic pursuits?

Short Answer

Expert verified
Answer: A 0.1:1 EROEI would be untenable in a pre-industrial setting because it would mean that for every unit of energy invested in food production, only 0.1 unit of energy would be gained in the form of food. This would lead to malnutrition, starvation, and the inability to continue food production. An exact 1:1 EROEI implies that the energy input required to produce food is equal to the energy output gained from the food itself, leaving no surplus energy for other activities such as building shelters, creating artwork, or engaging in other pursuits. This would hinder societal growth, wealth-building, and cultural development.

Step by step solution

01

1. Understanding EROEI

EROEI is the ratio of the energy output to the energy input required to produce that output. In the context of food production, it is the amount of energy contained in the produced food versus the amount of energy consumed to produce that food. A higher EROEI means that less energy is required to produce the same amount of food, making the production process more efficient.
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2. Reasons for untenability of 0.1:1 EROEI in pre-industrial settings

In a pre-industrial setting, the primary energy input for food production was muscle power from humans and animals. If the EROEI was 0.1:1, this would mean that for every unit of energy invested in food production, the output would only be 0.1 unit of energy in the form of food. Since humans and animals need more energy than they expend in order to survive and maintain their health, this EROEI ratio would be unsustainable in the long run, leading to malnutrition, starvation and ultimately, inability to continue food production.
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3. Describing the conditions for a 1:1 EROEI

An EROEI of 1:1 implies that the energy input required to produce food is equal to the energy output gained from the food itself. In this scenario, both humans and animals involved in food production would be barely able to sustain themselves only on the energy gained from the food they produce, without any energy left for other activities.
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4. Implications of 1:1 EROEI on other aspects of life

An EROEI of 1:1 would mean that all the effort and energy invested in food production would be utilized only to produce the amount of food required to maintain the same energy levels. This would leave no surplus energy for other activities such as building shelters, creating artwork, or engaging in other aesthetic pursuits. The society would not be able to grow, build wealth or develop culture under these circumstances.

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Most popular questions from this chapter

Replicate the conclusion of Box \(14.3\) by assuming one-quarter of the 2 trillion tons \(\left(5 \times 10^{1} 4 \mathrm{~kg}\right)\) of mass is combustible at \(4 \mathrm{kcal} / \mathrm{g}\). How long-in years-would this amount of energy last if burning at 18 TW?

If \(50 \mathrm{~kJ}\) of energy are spent to extract \(1 \mathrm{MJ}\) of energy content in the form of coal, what is the EROEI?

Re-express an EROEI of \(1.5: 1\) in terms of how many total units of energy must be produced in order to extract one unit of net energy in a self- supporting operation.

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A large tree might have a trunk \(0.5 \mathrm{~m}\) in diameter and be \(40 \mathrm{~m}\) tall. Even though it branches out many times, pretend all the wood fits into a cylinder maintaining this \(0.5 \mathrm{~m}\) diameter for the full height of the tree. Wood floats, \({ }^{33}\) so let's say it has a density around \(800 \mathrm{~kg} / \mathrm{m}^{3}\). How many kilograms of \(\mathrm{CO}_{2}\) did this tree pull out of the atmosphere to get its carbon, if we treat the tree's mass as \(50 \%\) carbon?
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