Renewable sources lifetime

Whatever the timescale, both of these resources are non-renewable and the realization that their lifetime may be comparatively short, together with the economics of exploiting, for example, shale oil and sincere worries about the use of nuclear power have led scientists to search for renewable sources of energy which might be exploitable on a commercial basis. 

Table 2.2A, B C lists the non-fossil energy sources that are potential candidates to fill all or part of our future energy needs as defined in Table 2.1. They are divided into renewable sources, nonrenewable sources with relatively short lifetime and non-renewable sources with a long lifetime. In this context, a lifetime less than 100 years is considered short.

The major alternative is coal but this is also a non-renewable energy source with a predicted useful lifetime of about 200 years. 

One must also examine possible barriers in the overall production of chemicals. However, there are some interesting similarities between the renewables and petrochemical industries. Both face the same three general issues for producing chemicals. First is an issue of supply. Both industries need to know the source of their feedstock, its lifetime, and methods for its removal from the structures in which it is found. Second, both industries must face issues of separation by determining what components are present in the feedstock and how these components are separated from one another. Finally, both industries face the issue of conversion. Once the building blocks are removed from the feedstock, they must be converted to products. Of these three... 

At this point, initial cost versus lifetime expenses often comes into play. A cheap answer looks good on the quarterly bottom line, but if it needs constant maintenance, the cost is a ruse. Many plant managers and/or quality control managers decide at this point that spectroscopic measurements are the least labor-intensive of any type on the market. The probe is usually passive, not needing to be renewed or cleaned at frequent intervals, and the most difficult maintenance on the spectrometer normally consists of replacing the source lamp on a yearly basis. 

The source of a feedstock may consist of a depleting resonrce, snch as petroleum, in which case the lifetime of the resource and the environmental implications of obtaining it must be considered. From the standpoint of sustainability, it is preferable to nse recycled materials as feedstocks, although the availability of recycled materials suitable for this purpose is usually limited. A third source that is very desirable consists of renewable resources, particularly from materials made by photosynthesis and biological processes. 

One of the common mythologies about plastics is that because they are made from oil or natural gas, which are non-renewable resources, their use should be discouraged to extend the useful lifetime of these raw materials for other purposes. Apart from the fact that chemical raw materials represent less than 5% of the total oil and gas production world-wide, plastics can be made from a wide variety of carbon sources, and in fact, the restriction of automobile speeds to 55 miles per hour in the US and more recent legislation on automobile fuel economy have saved more oil than was necessary to produce all of the world s plastics. 

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