EM SC 470
Applied Sustainability in Contemporary Culture

Resource Flows


Linear Resource Flow

The problems associated with the massive amount of resources used to produce everyday goods and services is compounded by the fact that this system is based mostly on linear resource use. This is often referred to as "take, make, waste." An illustration of the basic resource flow is shown below.

Linear resource flow model.
Figure 8.5. Linear resource flow model. Note that the width of the arrows gets smaller throughout the process due to losses (pollution and waste) along the way. 
Credit: D. Kasper, based on image by Ecocycle.

This linear model typically goes something like the following:

  • Natural resources are extracted through mining, growing, gathering, etc. They are often shipped all over the world, e.g., as indicated in the automobile infographic above.
  • These raw resources are then manufactured into final goods, both perishable and non-perishable. This almost always occurs on an industrial scale (think of the massive factory farms, manufacturing plants, and even the feed mill illustrated above).
  • These goods are then distributed, usually globally. Take a look at the label on your clothes (Bangladesh and Vietnam are common), electronics (China, most often), and food (could be anywhere - Chile, Mexico, New Zealand, etc.). 
  • They are then used by the end user.
  • Most of the time, they are then disposed of in a landfill.
  • Note that all along the way there are waste and emissions being generated, most of which are emitted or landfilled.

This model requires the constant input of raw natural resources because of the waste and emissions along the way, and because most of the "waste" is dumped in a landfill (and possibly incinerated), and all of this is done primarily with the use of non-renewable energy. This is a major reason why our ecological footprint is so large and we are using natural resources at such a high rate. Globally, only about 12.5% of the primary energy used is renewable (source: BP 2021 Statistical Review of World Energy). In the U.S., over half of municipal solid waste (MSW) ends up in a landfill. Keep in mind that municipal solid waste is basically household garbage, and does not include construction, industrial, or farming waste, which make up a large portion of the waste stream. All of this adds up to 292.2 million short tons of MSW generated (about 4.9 pounds per person per day, which is up from 4.5 pound per person per day a few years ago), of which about 146 million tons ends up in a landfill, according to the U.S. EPA.

1960 - 2018 municipal solid waste management in the U.S.

MSW by source, U.S. in 2018. landfill = 50%, recycling = 24%, combustion with energy recovery = 12%, composting = 8%, other food management = 6%

Figure 8.6. What happens to municipal solid waste in the U.S. Approximately 146 million tons of MSW end up the landfill every year.
Credit: U.S. EPA. To see full data, go to the EPA website.

Circular Resource Flow

Contrast this with a circular resource flow model, in which there is almost no waste. Any resources that are unused in each step are reintegrated back into the system. Manufacturing "waste" is reused or recycled, as are final products used by the end user. If this could all be run using renewable resources, then much of the pollution would be eliminated as well. In fact, in an ideal circular resource system, the idea of "waste" does not exist. This is the philosophy behind "zero waste" initiatives. Note that because of thermodynamics, there will be some inefficiency, and thus some loss. This is why there will still be some natural resource input required. 

Circular resource flow model.
Figure 8.7. Circular resource flow model. Note that the width of the resource extraction arrow is much smaller due to the reintegration of what would otherwise be considered "waste" back into the system.
Credit: D. Kasper

It is worth noting that nature utilizes circular resource flow. Recall that it was stated above that the concept of natural resources is anthropocentric. There is no waste in nature - everything is a resource for some other process. Resources move around in continuous flows, and all "waste" is reintegrated back into the system, with the exception of some heat loss that is radiated back to space. All of this is of course driven by renewable energy, and any energy lost to space is offset by energy coming in from the sun. This is why many zero waste (and other sustainability) advocates say that the more we can design human systems to mimic natural systems, the more sustainable those systems will be. As you will see in a future lesson, this is the fundamental philosophy of permaculture.

The Zero Waste Alliance provides an excellent visualization of what such a system could look like. The images below show natural resource flows. The thickness of the flows indicates the relative amount of resources flowing through that part of the system. As you can see, by recovering most of the "waste" throughout, the raw materials flow (at the far left of each diagram) is greatly reduced. Note that the second image shows an idealized flow - there will be some loss due to thermodynamics. Even without thermodynamic loss, some natural resource extraction is required because some resources cannot be directly reused in the manufacturing process. 

model of linear resource flow

circular resource flow model
Figures 8.8 and 8.9. Models of current resource flow vs. improved resource flows. Note that the thickness of the line indicates the relative amount of resources flowing through each part of the system.