Renewable resource

From Green Plastics

A renewable resource is a natural resource that is created in the environment faster than it is used up by people. Many people think of "renewability" as a fixed trait: some things (like trees, grass, and wind) are renewable, while others (like oil and coal) are not. In fact, whether a resource is renewable depends on both how fast it is replenished and how fast people use it. As a result, some resources are more renewable than others, and some resources may or may not be renewable depending on how they are used.

Rate of Renewal

The rate of rewal (sometimes also called the "sustainable yield") of a resource tells you how quickly it can be replenished by the environment.

Solar energy, tides, rainfall, and winds are considered perpetual resources for energy because they renew much faster than they could ever be used. (Can you imagine us "using up" the wind, so that we would have to wait until the earth made more?)

Living organisms provide the majority of resources that are generally considered "renewable", because they generally renew themelves within a reasonable amount of time relative to how quickly they are use. Agricultural feedstocks and marine feedstocks are two major categories of living organism feedstocks. Within this category, some organisms renew faster than others: for example, it takes much longer to grow a new tree than it does to grow grass.

Most of the resources that are considered "non-renewable" are based on coal, oil, natural gas, and other substances that take so long for the environment to create that almost any use of these resources at all will cause them to be used up before any more is created. Petro-chemical feedstocks are feedstocks derived from petroleum principally for the manufacture of chemicals, synthetic rubber, and a variety of plastics.

Rate of Use

Imagine you live in a small village by a river. A turbine on the river spins, and it can generate enough electricity for the entire village every day. Clearly, their hydroelectric power is a completely renewable resource. However, as the size of the village grows, their energy use grows. If eventually the needs of the village far outstrip the energy that can be provided by the turbine, then the hydroelectric energy from the river is no longer a renewable resource for the village: the rate of use has exceeded the rate of replenishment.

The same issue exists for the use of plants. As long as our use of (for example) corn remains moderate compared to the amount of corn produced, corn is a renewable resource. However, if our use of corn increases dramatically without a corresponding increase in corn crop production, then corn will cease to be a renewable resource: we will use it all up, and we will either have to cease production until the corn renews itself or (worse) it will become extinct, so it will not replenish at all.

Plastic Feedstocks and Renewability

(It would be nice to put a table here of various resources used to make plastic, and their relative rates of renewability)