Using Resources & Life Cycle Assessment
Finite and Renewable Resources
The resources we use come from the Earth’s crust, oceans and atmosphere. Some resources are finite (non-renewable) — they are being used faster than they can be replaced. Fossil fuels, metal ores and minerals are all finite resources. Other resources are renewable, meaning they can be replenished, such as timber from managed forests or crops.
Finite resources (such as crude oil and metal ores) are being used up and cannot be replaced. Renewable resources (such as timber and crops) can be replenished.
Recycling Metals
Metals are extracted from ores found in the Earth’s crust. Extracting metals from their ores requires large amounts of energy and has significant environmental impacts, including mining damage to landscapes, noise, dust, and loss of habitats. Recycling metals offers several advantages over extracting new metal from ore.
Recycling metals uses less energy than extracting metals from ores, which reduces carbon dioxide emissions and saves money. It conserves finite resources by reducing the amount of ore that needs to be mined. It also reduces the amount of waste going to landfill and reduces the environmental damage caused by mining operations. However, metals must be sorted and cleaned before recycling, which adds cost and complexity.
What Is a Life Cycle Assessment?
A life cycle assessment (LCA) evaluates the environmental impact of a product throughout its entire life — from raw material extraction to final disposal. The four key stages are:
- Extracting and processing raw materials — mining ores, drilling for oil, growing crops. This often involves energy use, habitat destruction and pollution.
- Manufacturing and packaging — turning raw materials into products. This requires energy (often from fossil fuels), produces waste, and may use water and chemicals.
- Use and operation — the energy and resources consumed while the product is being used. For example, a car uses fuel and produces exhaust emissions throughout its life.
- Disposal — what happens at the end of the product’s useful life. Options include landfill, incineration, or recycling. Each has different environmental consequences.
A life cycle assessment considers the environmental impact at four stages: extracting raw materials, manufacturing, use, and disposal. It helps companies and consumers make more sustainable choices.
Life cycle assessments can be difficult to carry out accurately. Some environmental impacts are hard to quantify — for example, how do you measure the value of lost biodiversity or visual pollution? Different assessors may also give different weightings to different impacts, introducing bias. Companies may selectively present LCA data to make their products look more environmentally friendly than they really are, a practice sometimes called greenwashing.
The Use and Disposal Stages
The ‘use’ stage of a product’s life can have a larger environmental impact than its manufacture. A car, for example, burns fuel and produces exhaust emissions throughout its entire working life — far more CO\(_2\) than was released during its construction. Electrical products consume energy from the grid, which may come from fossil fuel power stations. The disposal stage also matters: landfill takes up space and can pollute groundwater, incineration releases CO\(_2\) and potentially toxic gases, while recycling requires energy for collection and reprocessing but avoids the need for new raw materials.
Reducing the Use of Resources
There are three main strategies for reducing the impact on finite resources, often called the “three Rs”:
- Reduce — use fewer resources in the first place. For example, using less packaging or making products that last longer.
- Reuse — use items again instead of throwing them away. Glass bottles can be collected, washed and refilled.
- Recycle — collect and reprocess materials to make new products. Metals, glass, paper and some plastics can be recycled.
Phytoextraction uses plants to absorb metal compounds from the soil. The plants are then harvested and burned, and the metals are extracted from the ash. Bioleaching uses bacteria to produce acidic solutions that dissolve metal compounds from low-grade ores. Both methods are slower than traditional mining but have lower environmental impact and can extract metals from ores that would otherwise be uneconomic to mine.
Recycling metals uses less energy, reduces CO\(_2\) emissions, conserves finite ore reserves and reduces landfill waste compared to extracting new metals from ores.
Using Resources Sustainably
Sustainable development means meeting the needs of the current generation without compromising the ability of future generations to meet their own needs. Chemistry plays a key role through developing new materials, improving recycling processes, and finding ways to use renewable resources instead of finite ones.
When evaluating a life cycle assessment, consider all four stages and think about which stages have the greatest environmental impact for that particular product. Remember that some impacts are subjective and difficult to quantify, which is a limitation of LCAs.