4.10.1.1,4.10.2.2 - Resources, sustainability, reuse and recycling

Finite and renewable resources

A resource is a supply of a substance or material that people can use to meet a need.

Humans use resources for warmth, shelter, food and transport. Timber can provide a building frame, crops provide food and cotton for clothing, and fuels provide energy for heating and moving vehicles. These products often begin with natural resources: substances obtained from the Earth, oceans or atmosphere. Agriculture supplements natural supplies by growing crops, raising animals and managing forests rather than relying only on collection from the wild. Cultivated cotton supplements natural fibre supplies; managed forests supply timber; farmed fish supplement wild catches.

A resource is finite if it is used faster than natural processes replace it on a human timescale. Crude oil forms over geological timescales, so new oil does not replace the amount consumed during a person's lifetime. Metal ores, limestone and other minerals also have limited accessible supplies. An abundant resource can still be finite: abundance concerns how much exists, whereas renewability concerns its replacement.

Timber can be renewable if trees are replanted and allowed to grow as quickly as timber is removed. Cutting a forest much faster than it regrows makes that particular use unsustainable. “Natural” does not mean “renewable”: crude oil is natural and finite. Equally, calling a resource renewable does not mean it is available in unlimited quantities at every location.

Reading the scale of resource data

An order of magnitude is a factor of about ten. Illustrative annual data give a town's use as $3.0\times10^3\,\mathrm{kg}$ of metal and $2.0\times10^6\,\mathrm{kg}$ of aggregate. Divide values in matching units before interpreting their scale.

Aggregate use is roughly three orders of magnitude larger. The larger mass saving does not alone prove the larger environmental benefit: extraction damage, scarcity and energy per kilogram also matter.

For a second comparison, a stock table lists $4.0\,\mathrm{t}$ of timber and $500\,\mathrm{kg}$ of polymer. Convert tonnes before finding a mass ratio.

Timber mass is eight times larger, rather than $4/500$ times larger. Check the unit and scale before comparing a table's numbers or a chart's bar heights.

Chemistry and sustainable development

Chemistry changes resources into useful products and can reduce the resources needed to make them.

Crude oil is processed into fuels and feedstocks for synthetic polymers. Metal compounds in ores are converted into metals. Nitrogen from the atmosphere is converted into ammonia and then fertilisers. Resources from the Earth, oceans and atmosphere can all need processing: ores provide metals, seawater can supply salts after separation, and air supplies nitrogen for ammonia manufacture. These examples show why a resource may need processing before it provides a useful material or energy supply.

Natural products can be supplemented or replaced by synthetic ones. Synthetic rubber can replace or supplement rubber obtained from trees; polyester can supplement cotton fibres for clothing. Replacement does not automatically improve sustainability. A synthetic material may be durable and need less farmland, but use finite feedstocks and cause disposal problems. A natural product may regrow, but need water, land, fertilisers and processing energy. Compare how each product is made, used and discarded.

Chemistry contributes by improving agricultural and industrial processes. A fertiliser supplies nutrients that crops need, potentially increasing the food produced from farmland. Its benefit must be balanced against the energy and raw materials used in manufacture and harm caused if nutrients escape into waterways. The useful aim is efficient delivery of the needed nutrient, rather than adding the largest possible quantity.

In industry, a catalyst can enable useful production at a lower temperature or increase production rate under existing conditions. A process producing less waste uses more of the input as a useful product and reduces disposal needs. Developing materials that last longer can reduce replacement demand. These improvements conserve resources, but a judgement still needs evidence: a lower-temperature process might consume more of another scarce material. Sustainable development considers current benefits alongside future resource availability and environmental effects.