Green Energy: Clean Power, No Greenhouse Gas Emissions

Greenhouse gases are gases that trap heat in the Earth's atmosphere, causing global warming and climate change. They are produced by human activities such as burning fossil fuels, industrial processes, transportation, and agriculture, as well as natural sources such as solid waste, trees, and other biological materials. These gases, including carbon dioxide, methane, nitrous oxide, and fluorinated gases, can remain in the atmosphere for extended periods, ranging from a few years to thousands of years. While greenhouse gases have kept the Earth habitable for humans and other species, their increasing concentrations are causing extreme weather, rising sea levels, and adverse health effects. Addressing air pollution and reducing greenhouse gas emissions are crucial steps towards ensuring a sustainable future and mitigating the impacts of climate change.

Carbon dioxide (CO2) from burning fossil fuels

Carbon dioxide (CO2) is released into the atmosphere through the burning of fossil fuels, such as coal, oil, and gas. Fossil fuels are formed from the decomposition of carbon-based organisms that died millions of years ago, creating carbon-rich deposits that are extracted and burned for energy. This process releases carbon dioxide into the atmosphere, contributing to the greenhouse effect and global warming.

According to the World Resources Institute, worldwide emissions of carbon dioxide from burning fossil fuels total about 34 billion tonnes per year, with coal contributing about 45%, oil 35%, and gas 20%. The Intergovernmental Panel on Climate Change (IPCC) has found that emissions from fossil fuels are the dominant cause of global warming. In 2018, 89% of global CO2 emissions came from fossil fuels and industry.

The burning of fossil fuels releases carbon dioxide into the atmosphere, which acts as a greenhouse gas. Greenhouse gases, such as carbon dioxide, have far-ranging environmental and health effects. They trap heat from the sun, leading to warmer temperatures and the hallmarks of climate change, including rising sea levels, more extreme weather, heat-related deaths, and the increased transmission of infectious diseases. Carbon dioxide is the primary greenhouse gas, responsible for about three-quarters of emissions. It can remain in the atmosphere for thousands of years.

The concentration of carbon dioxide in the atmosphere has been increasing since the beginning of the industrial era, with levels in 2023 reaching 420 parts per million, the highest ever recorded. This rise in carbon dioxide and other greenhouse gas concentrations is the primary reason for the planet's soaring temperatures. To limit global warming, the IPCC warns that fossil fuel emissions must be halved within 11 years.

There have been proposals to capture CO2 emissions from burning fossil fuels in large plants and inject them underground, known as carbon capture and storage (CCS). However, this method is difficult and expensive to implement, and it has not shown much progress in terms of technical feasibility. Therefore, a mass switch to renewable energy sources is necessary to reduce carbon dioxide emissions from burning fossil fuels and mitigate their impact on the planet's climate and human health.

Methane (CH4) from landfills and agriculture

Greenhouse gases trap heat in the atmosphere, leading to warmer temperatures and the hallmarks of climate change: rising sea levels, extreme weather, heat-related deaths, and increased transmission of infectious diseases. While carbon dioxide (CO2) is the most common greenhouse gas, methane (CH4) is significantly more potent and destructive.

Methane (CH4) is a heat-trapping gas that contributes to global warming. It is emitted during the decomposition of organic waste in landfills and through agricultural practices. Landfills are a significant source of methane, as the decomposition of waste such as kitchen scraps, paper, and spoiled canned goods produces this gas. The challenge of reducing methane emissions from landfills lies in quantifying the amount of gas released and implementing effective mitigation strategies.

Agriculture is the largest anthropogenic source of methane (CH4), with emissions arising from enteric fermentation, manure management, rice cultivation, and residue burning. Climate change can alter CH4 fluxes from agriculture, impacting future emissions. Changes in feed quantity and quality, increased animal heat stress, higher manure fermentation rates, and greater pest and disease impacts may enhance methane emissions from livestock.

Mitigation strategies in agriculture aim for a 25% reduction in non-CO2 emissions by 2050. These include interventions on the supply side, such as improved rice and manure management, and demand-side measures like shifting to plant-based diets and reducing food waste. Biogas, generated from the anaerobic decomposition of organic matter, can also help reduce unabated CH4 emissions from animal manures.

Addressing methane emissions from landfills and agriculture is crucial for mitigating climate change and its associated impacts on human health and the planet. While challenges exist in quantifying and curbing these emissions, implementing effective strategies can significantly reduce atmospheric warming and contribute to global efforts in combating climate change.

Nitrous oxide (N2O) from fertiliser and manure

Greenhouse gases are gases that trap heat in the Earth's atmosphere, leading to global warming and climate change. The primary greenhouse gas is carbon dioxide, which is released into the atmosphere through the burning of fossil fuels, solid waste, trees, and other biological materials. Methane, another potent greenhouse gas, is released from landfills, the natural gas and petroleum industries, and agriculture.

Nitrous oxide (N2O) is a greenhouse gas that is less prevalent than carbon dioxide, constituting about six percent of global greenhouse gas emissions. However, it is significantly more potent, with 264 times the heat-trapping potential of carbon dioxide over a 20-year period. According to the Intergovernmental Panel on Climate Change (IPCC), N2O can remain in the atmosphere for over a century.

Agriculture and livestock are the primary sources of nitrous oxide emissions, including fertilizer use, manure, and the burning of agricultural residues. In recent decades, the application of nitrogen (N) fertilizer to wheat fields has doubled, leading to increased N2O emissions. This is particularly prominent when the amount of fertilizer exceeds the crop's nitrogen requirements, resulting in lower nitrogen use efficiency.

To mitigate N2O emissions from fertilizer use, farmers can employ various strategies. One approach is to match the amount of nitrogen applied through fertilizer to the crop's nitrogen needs. This ensures that excess fertilizer, which is susceptible to loss, is minimized. Additionally, applying fertilizer when it is most needed by plants can reduce N2O emissions. For example, sidedressing N fertilizer at the V-6 stage in corn or applying fertilizer a few weeks after planting can increase the likelihood that the nitrogen will be taken up by the crop rather than lost to the atmosphere.

By implementing these management practices, farmers can play a crucial role in reducing N2O emissions from fertilizer and manure use, contributing to the global efforts to combat climate change and reduce the environmental impact of agricultural practices.

Fluorinated gases from household and industrial applications

Fluorinated gases (F-gases) are a group of synthetic greenhouse gases that contain fluorine. They are potent greenhouse gases with high global warming potential (GWP) and are emitted from a range of household and industrial applications.

F-gases are primarily emitted in smaller quantities than other greenhouse gases, but due to their high GWP, they trap substantially more heat than carbon dioxide (CO2) for a given amount of mass. The main types of F-gases include hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). These gases are emitted from various household and industrial products and processes, with HFCs being the largest and fastest-growing source of fluorinated gas emissions.

Household Applications

F-gases are commonly used in household applications such as refrigeration and air conditioning systems. HFCs, in particular, are used as coolants in refrigerators and air conditioners, which can leak out slowly over time, contributing to emissions. Additionally, HFCs are utilized as propellants in aerosol sprays, releasing these gases directly into the atmosphere each time the spray is used.

Industrial Applications

F-gases also have a wide range of industrial applications. They are used in commercial refrigeration, heat pumps, fire suppression systems, electronics, aerospace, and the magnesium industry. In the electronics industry, for example, nitrogen trifluoride (NF3) is used as an etchant for microelectronics fabrication. Meanwhile, SF6 is primarily employed as an arc suppression and insulation gas in high-voltage switchgear and the production of magnesium.

Efforts to Reduce Emissions

Recognizing the potential global warming effects of F-gases, various efforts have been made to reduce their emissions. The Kigali Amendment, signed in 2016, mandates a phase-down of HFC production and consumption. Similarly, the American Innovation and Manufacturing Act aims for an 85% reduction in the use of HFC refrigerants by 2035. These measures are crucial in mitigating the impact of F-gases on climate change and protecting the ozone layer.

Ozone (O3) from reactions among pollutants in the air

Ozone (O3) is a gas molecule composed of three oxygen atoms. It can be “good” or “bad” depending on where it is found in the atmosphere.

Stratospheric ozone is "good" because it occurs naturally in the upper atmosphere, where it forms a protective layer that acts as a shield from the sun's harmful ultraviolet radiation.

Ground-level ozone, on the other hand, is "bad" and considered a harmful air pollutant. It is formed by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOCs) in the presence of sunlight. These precursor pollutants are emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources.

Ground-level ozone is the main ingredient in smog and can trigger a variety of health problems, particularly for children, the elderly, and people with pre-existing lung diseases such as asthma. It can also lead to increased respiratory illnesses, metabolic disorders, nervous system issues, and reproductive issues.

Ozone is transported by wind and can reach high concentrations far from the original sources of pollution, including across international borders and oceans. This makes assessing and tackling exposure to ozone challenging.

While there are no major direct emission sources of ozone in the UK, it is still a concern due to the contribution of precursor pollutants, such as methane, and the transport of ozone from outside the UK.

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