Table of Contents
Overview
Conventional energy usually refers to fossil fuels such as coal, oil, and natural gas, along with traditional large-scale nuclear power. These sources have powered industrial development for more than a century, but they also create a wide range of environmental impacts across their entire life cycle. Extraction, processing, transport, and final use all contribute to pollution and ecological damage.
This chapter focuses on the main environmental consequences that are specific to conventional energy systems. It prepares the ground for understanding why renewable energy is being promoted and how it can help reduce these impacts, without going into the detailed benefits of renewables themselves, which belong to other chapters.
Life Cycle Perspective
Every conventional energy source has a chain of activities, from exploration and extraction, through refining or processing, to combustion or final use and waste handling. Environmental impacts occur at each of these stages.
For coal, this includes mining the coal, transporting it, burning it in power plants, and managing the ash and other residues. For oil, it means drilling wells onshore or offshore, moving crude oil by ship or pipeline, refining it into fuels like gasoline and diesel, transporting those fuels, burning them in engines, and dealing with spills and leaks. For natural gas, it involves gas fields and wells, often including techniques like hydraulic fracturing, pipelines and liquefied natural gas terminals, and combustion in power plants, industry, and buildings. For nuclear power, mining and processing uranium, operating reactors, handling spent fuel, and storing or disposing of radioactive waste are the key steps.
Thinking in terms of this full chain helps to see that environmental impacts are not only at the point of combustion, but are spread across the whole system.
Air Pollution
One of the most visible and harmful impacts of conventional energy is air pollution. Combustion of fossil fuels releases gases and particles that affect both local air quality and the global atmosphere.
Coal-fired power plants emit sulfur dioxide, nitrogen oxides, fine particulate matter, mercury, and other toxic metals. Oil products in vehicles and industry generate nitrogen oxides, carbon monoxide, volatile organic compounds, and particulates, especially from diesel engines. Natural gas is often described as cleaner in terms of some pollutants, but burning it still produces nitrogen oxides and fine particles, and leaks of unburned gas contribute to atmospheric pollution. Traditional biomass burned inefficiently is also a major source of smoke and particulates, although it is usually discussed separately from fossil fuels.
These pollutants irritate lungs, trigger asthma, and contribute to chronic heart and respiratory diseases. They also create regional problems like smog and acidification of rain and soils. Air pollution from conventional energy is a leading environmental health risk worldwide.
Key point: Combustion of fossil fuels is a primary source of harmful air pollutants such as sulfur dioxide (SO₂), nitrogen oxides (NOₓ), fine particulate matter (PM), and toxic metals, with major impacts on human health and ecosystems.
Greenhouse Gas Emissions
Conventional energy is closely linked to climate change because it is the main source of greenhouse gas emissions. Burning fossil fuels releases carbon dioxide, which accumulates in the atmosphere and traps heat. Some stages of extraction and transport, especially for oil and gas, also release methane, which is a very potent greenhouse gas over short time scales.
Coal is the most carbon intensive major fuel when burnt for electricity or heat. Oil products follow, with emissions from both fuel combustion and associated processes like flaring at production sites. Natural gas has lower carbon dioxide emissions per unit of energy when burned, but if significant amounts of methane leak along the supply chain, the climate advantage can be reduced or even lost.
Nuclear power does not produce greenhouse gases at the point of electricity generation, but there are emissions associated with uranium mining, fuel processing, plant construction, and decommissioning. These typically remain much lower than for fossil fuel based power, yet they are not zero.
The high dependence of modern economies on fossil fuels means that the majority of human-caused greenhouse gas emissions are tied to conventional energy systems, primarily through electricity generation, transport fuels, and industrial heat and processes.
Water Use And Pollution
Conventional energy systems place heavy demands on freshwater resources and can degrade water quality. Many thermal power plants, including coal, gas, and nuclear, use large quantities of water for cooling. This can lead to significant water withdrawals from rivers, lakes, or aquifers, which affects other users and aquatic ecosystems. Warm water discharged back into rivers can raise temperatures and stress aquatic life.
Coal mining often contaminates streams and groundwater with acidic drainage, metals, and sediments. Oil and gas extraction can bring naturally occurring salts, metals, and sometimes radioactive materials to the surface with produced water, which requires careful treatment. Hydraulic fracturing uses large volumes of water mixed with chemicals, and improper handling of wastewater can contaminate surface or groundwater.
Oil spills on water, whether from tanker accidents, pipeline leaks, or offshore drilling, create acute pollution events. Spilled oil spreads on the surface, coats shorelines, and harms fish, birds, and marine mammals. Cleanup is difficult and long term ecological damage can be substantial.
Important statement: Conventional energy production and use often involve high water withdrawals, thermal pollution, and contamination by chemicals, metals, or hydrocarbons, putting stress on freshwater and marine ecosystems.
Land Degradation And Habitat Loss
Extracting and using conventional energy can transform landscapes and damage habitats. Surface coal mining, including open pit and mountaintop removal methods, strips vegetation and soil, leaving large disturbed areas. Reclaiming these lands is technically possible but can be slow and incomplete, with altered soil structure and reduced biodiversity.
Oil and gas exploration and production create networks of roads, well pads, and pipelines that fragment habitats. This fragmentation can disturb wildlife, affect migration routes, and introduce invasive species. In sensitive areas, such as rainforests, Arctic regions, or wetlands, even small disturbances can have large ecological consequences.
Infrastructure for conventional energy, such as refineries, storage terminals, large power plants, and associated transport corridors, occupies considerable land and can concentrate pollution in specific regions. Urban and industrial areas around these facilities often experience degraded environmental conditions and reduced access to green space.
Nuclear energy facilities also require land, but their most distinctive land-related impact is not area alone. It is the long term requirement to manage sites where radioactive materials are handled, including spent fuel storage and potential repositories. These facilities constrain land use over long periods and must be protected from intrusion and natural hazards.
Waste Generation And Hazardous Materials
Conventional energy produces large amounts of solid and liquid wastes, many of which are hazardous. Coal combustion leaves ash that contains heavy metals and must be stored in landfills or ash ponds. Poorly managed ash storage can lead to leaks or sudden releases that contaminate rivers and soils.
Oil refining produces sludges and residues that need careful handling. Used lubricating oils, solvent wastes, and other by-products from fossil fuel use in industry can accumulate in the environment if not managed properly. Leaks from underground fuel storage tanks can contaminate soils and groundwater.
Nuclear power generates radioactive wastes of varying levels. Low and intermediate level wastes include contaminated equipment and materials. High level waste is mostly spent nuclear fuel or its separated products. These materials remain hazardous for very long timescales and require isolation from living organisms. Interim storage methods and the design of deep geological repositories are intended to prevent releases, but the very long durations involved make waste management a central environmental concern for nuclear energy.
Critical rule: Hazardous wastes from conventional energy, particularly coal ash and radioactive materials, must be isolated and managed over long periods to prevent contamination of air, water, and soil.
Accidents, Spills, And Catastrophic Risks
Conventional energy systems carry risks of accidents that can have dramatic environmental effects. Oil spills from tankers or offshore platforms are well known examples. They release large quantities of oil quickly into marine environments, causing immediate and often long lasting harm to coastal and ocean ecosystems.
Coal mining accidents can cause sudden collapses, explosions, and floods that not only threaten miners but also release pollutants into surroundings. Tailings dam failures at mines can spread contaminated sediments downstream.
Natural gas systems can experience explosions or fires in wells, processing plants, or pipelines. Besides immediate safety risks, such incidents may release large volumes of methane and other gases.
Nuclear energy has a specific type of catastrophic risk. Severe accidents in nuclear reactors can release radioactive materials into the environment, as occurred in past events. Such releases affect large areas and require evacuation, long term exclusion zones, and complex cleanup efforts. Although severe nuclear accidents are rare, their potential consequences for health and ecosystems are a major part of the environmental debate around nuclear power.
Impacts On Ecosystems And Biodiversity
Across all these pathways, conventional energy affects ecosystems and biodiversity in multiple ways. Air pollution can lead to acidification of soils and waters, damaging forests and freshwater ecosystems. Deposition of heavy metals and organic pollutants can accumulate in food chains, affecting both wildlife and humans who depend on these ecosystems.
Water withdrawals and discharges alter river flows and temperatures, which changes habitat conditions for fish and invertebrates. Pollution from spills and leaks can destroy wetlands and coral reefs, or reduce the productivity of coastal zones that support fisheries.
Habitat fragmentation from roads, pipelines, and transmission lines makes it harder for many species to find food, mates, and shelter. Noise and light from industrial activities disturb animal behavior and can reduce reproductive success.
Over time, the combination of these pressures contributes to declines in species populations and the loss of ecological functions. This loss can also undermine ecosystem services that humans rely on, such as clean water, fertile soils, and natural protection from storms and floods.
Health And Social Dimensions Of Environmental Impacts
The environmental impacts of conventional energy are closely tied to human health and social outcomes. Communities located near mines, refineries, power plants, and major transport routes are often exposed to higher levels of air and water pollution. This exposure is linked to increased rates of respiratory and cardiovascular diseases, some cancers, and other health problems.
In many regions, disadvantaged or marginalized communities bear a disproportionate share of these burdens. They may have less influence over where facilities are located or how strictly they are regulated. This raises questions of environmental justice and equity, as the benefits of energy use are spread broadly, but the direct environmental harms are concentrated in specific places.
Livelihoods that depend on healthy ecosystems, such as small scale fishing or agriculture, can be damaged by pollution and land degradation from energy activities. This adds economic and cultural impacts to the direct environmental ones.
Linking Environmental Impacts To Energy Choices
Understanding the environmental impacts of conventional energy is essential when comparing different energy options. These impacts occur at local, regional, and global scales, and they operate over short and very long times. They involve air, water, land, and living organisms, and they connect directly to human health and social well-being.
Conventional energy has provided reliable power and fuels for decades, but it also creates significant environmental costs that are not always fully reflected in market prices. Recognizing these costs is a key step toward evaluating alternatives and designing policies that favor cleaner and more sustainable energy systems.