This page has been adapted from material at carbonneutral.com
Carbon offsetting is done by purchasing carbon credits. This money is then used to finance renewable energy, forestry and resource conservation projects which generate reductions in greenhouse gas emissions. To ensure this finance delivers genuine results, the projects which are supported must be high quality and ‘additional’, proving that they would not happen without the sale of carbon credits. Projects adhere to rigorous validation and verification procedures to demonstrate that they are generating emission reductions and they are monitored on a regular basis through independent third parties. Third-party standards include the Verified Carbon Standard, Gold Standard, Climate Action Registry, American Carbon Registry and the Clean Development Mechanism.
Any carbon management programme should always include reductions, such as reducing energy use, business travel and waste. However, for many households and businesses, there is a point at which the emission reductions that can be achieved are cost-prohibitive or will have a negative impact on performance. It is at this point that a carbon offset programme can deliver results that would otherwise not happen.
Offsetting one tonne of carbon with a carbon credit means there will be one less tonne of carbon dioxide in the atmosphere than there would otherwise have been.
Projects which sell carbon credits include wind farms which displace fossil fuels, household device projects which reduce fuel requirements for cookstoves and boiling water in low-income households, forest protection from illegal logging, methane capture from landfill gas and agriculture, reforestation for small-hold farmers and run-of-river hydro power and geothermal energy. These projects have to demonstrate that they require carbon finance from the sale of carbon credits to be financially viable and achieve greenhouse gas emission reductions. Most of these projects would not be financially viable without the finance delivered through the sale of carbon credits.
Many projects also deliver added benefits to local communities and the environment, such as job creation, health and well-being improvements and protection of biodiversity.
Wastewater is liquid from homes, businesses or agriculture which contains residual solids and a wide range of potential contaminants.
Wastewater treatment involves anaerobic digestion where bacteria digest the solids, creating significant amounts of biogas. This gas – primarily consisting of methane and carbon dioxide – can be captured and used to run engine/generators to produce electricity, heat or a combination of both. Using biogas in this way reduces greenhouse gases in two ways: it prevents the release of methane which is 21 times more potent than CO2 and displaces energy that would otherwise have been derived from fossil fuel sources. Alongside greenhouse gas reductions, wastewater treatment systems can improve water conservation in factory processes and reduce the release of toxic compounds and odours.
2.7 billion people, or one-third of humanity, cook with wood-burning cookstoves. This contributes to climate change, deforestation and poor health.
This type of project subsidises the cost of fuel-efficient cookstoves which reduce fuel requirements to mitigate deforestation as well as saving time and money in poor communities. Some of the world’s poorest families spend up to six hours a day, and around 20% of their annual income on fuel for cooking and heating.
According to the World Health Organisation (WHO), in low-income countries, indoor smoke from wood use is the sixth highest risk factor for premature deaths, contributing to more than 1.3 million deaths per year. The number of premature deaths from household air pollution is greater than the number from malaria or tuberculosis, and women and children are disproportionately affected as they are often responsible for cooking in the least developed countries.
Behaviour change projects provide educational programmes and improved technologies that enable communities to use alternative methods to reduce emissions. They deliver direct social and economic benefits for residents as well as measurable net carbon reductions.
Domestic behaviour change projects often start with a programme of educational workshops, with community liaison staff available to assist with questions during the implementation period. The projects have clear assessment methodologies, and combined monitoring and maintenance programmes ensure they are correctly carried out over their lifetime.
Geothermal energy derives from the earth’s heat. This heat can be used for direct heating (i.e. heating homes and buildings) and for generating electricity or a combination of the both (co-generation).
Geothermal power plants are located in places where the Earth’s heat can be harnessed using underground reservoirs relatively close to the surface. The power plants then route hot fluid (steam or hot water) from the geothermal reservoir through a turbine/generator – either directly or through a heat exchanger – to produce electricity. Geothermal is considered renewable because the heat in the Earth’s core is so abundant that minute amounts removed for energy production do not deplete this resource.
Biomass fuel switch
Biomass includes plants, crops, trees and waste products from milling and agricultural processes. Biomass can substitute fossil fuels – either in part or in full – to generate electricity, heat or both (known as co-generation).
Sustainably harvested timber is considered a renewable source of biomass because the trees that are removed are regrown, resulting in no net loss of stored CO2. Waste material such as bagasse (sugar cane stalks) and rice husk are another source of renewable biomass as they are by-products of existing agricultural processes. Using waste biomass for fuel can improve energy sustainability, provide additional income to farmers and overcome disposal issues. Switching to renewable sources of biomass not only prevents the release of CO2 from fossil fuels, but it also avoids the ecological damage associated with mining, drilling and transportation of these fuels.
Coal mine methane
Coal mine methane is released from coal and surrounding rock strata through mining practices. Methane is an explosive gas which is hazardous to miners so is usually extracted and released into the atmosphere. However, methane is also a potent greenhouse gas so preventing its release into the atmosphere presents an important opportunity to lower global emissions.
Coal mine methane is primarily released from:
- drainage systems that use wells to extract methane before mining
- ventilation systems that circulate fresh air to dilute in-mine concentrations to below explosive levels
- closed/abandoned mines from where coal mine methane escapes over many years through open shafts and cracks.
Installing wells which extract coal mine methane for capture and combustion prevents it from being vented into the atmosphere. During combustion, methane is converted into carbon dioxide which significantly reduces its global warming potential. In some instances, this waste gas is also captured and utilised to produce power and heat. This displaces energy produced from fossil fuel power stations, further lowering greenhouse gas emissions.
Afforestation and Reforestation
Afforestation and reforestation projects are the planting or seeding of non-forested land.
Deforestation is responsible for between 15 and 20% of global carbon emissions and afforestation and reforestation projects are essential to the reduction of carbon emissions around the world. The difference between them is the length of time the land has not been a forest; for afforestation, it is for at least 50 years and for reforestation it is since 31 December 1989.
As forests grow the trees absorb CO2 from the atmosphere through photosynthesis and sequester it within their growing biomass. This sequestered carbon stock is reliant on the forest remaining intact. Although some CO2 is released as the forest breathes, a forest that is growing and sustainable absorbs much more carbon than it releases and approximately 50% of dry matter within forest ecosystems is carbon.
Forest ecosystems are a living environment in a state of natural flux: as carbon is sequestered in forests, it is exposed to the risk of release through infrequent events such as forest fire or insect attacks. To address this risk of non-permanence, the Voluntary Carbon Standard requires that upon verification of carbon credits, a percentage is withheld in a central buffer from each project. These units are withheld from sale and used as insurance for any adverse events which would unexpectedly reduce the forest’s carbon stock.
Biomass is the biological matter mainly coming from dead trees, yard clippings, left-over crops, wood chips, sawdust from lumber mills and livestock manure. It is a renewable resource which can be burnt as fuel to produce energy.
Biomass cogeneration plants use renewable biomass to simultaneously produce both electric power and steam, using less fuel than traditional facilities to produce the same amount of energy.
In addition to the environmental benefit of using renewable fuels, biomass cogeneration plants are 50 to 70% more efficient than conventional fossil fuel power.
Waste heat recovery
Waste heat is the heat produced by machines, electrical equipment and industrial processes. Generally, it is considered a useless by-product and discarded. Capturing waste heat from large industrial plants allows it to be extracted and recycled back into the system.
Waste heat recovery boilers are usually placed on top of the heat sources and are used to generate steam which powers turbine generators and produces electricity, thereby reducing the environmental impact of industrial processes through their reliance of fossil fuel.
Methane is a potent greenhouse gas which can be extracted from landfills through wells dug at intervals throughout the site. It is the piped for combustion and/or use for power generation.
Combustion of methane converts the gas to carbon dioxide which has a significantly lower global warming potential than methane. To create power, generators are installed, converting the gas into power and heat.A landfill is a site for the disposal of a variety of waste materials including household, commercial, industrial and non-hazardous solid waste. Landfills range from open dumps to carefully designed and managed sophisticated structures built into or on top of the ground.
In the absence of oxygen, bacteria in the landfill breaks down the waste to produce landfill gas, consisting of around 50% methane, 50% carbon dioxide and a minute amount of non-methane organic compounds.
The capture of methane from landfill gas not only reduces GHG emissions but also prevents the release of toxic, volatile organic compounds and odours.
Wind power is an abundant energy resource which can be used to generate clean electricity through wind turbines.
The wind flowing through the turbines spins large propeller-like rotor blades. The movement of the blades rotates a shaft which is connected to an electrical generator which converts the kinetic energy of the wind into electrical energy. The output of wind turbine depends on the turbine’s size and the speed of the wind through the blades. The power generated by utility-scale turbines ranges from 100 kilowatts to as much as five megawatts. Grouped together into wind farms, turbines provide bulk power to the electrical grid which is then sent through transmission and distribution lines to homes and businesses.
Agricultural methane biogas
Methane released from manure management systems can be captured and used to produce clean energy through an anaerobic digester. These digesters are tight, oxygen-free containers which organic material such as animal manure and food scraps are fed into.
Naturally occurring bacteria in the organic waste breaks it down to produce methane gas, commonly known as biogas. Using generators, this gas is converted into electricity, delivering two environmental benefits. Firstly, reducing the volume of methane released into the atmosphere, and secondly, reducing the requirement for electricity from fossil fuel powered plants.
Livestock manure contributes approximately four percent of total human-induced methane emissions. Methane is a potent greenhouse gas, considered to be 25 times stronger than CO2 regarding its impact on global warming.
Methane is produced and emitted during the decomposition of organic material in livestock manure. Three groups of animals – swine, dairy and non-dairy cattle – account for 80% of the methane from livestock.
Hydroelectric power, or hydropower, is electricity generated from the energy of moving water.
The water is released into large turbines and the pressure makes the turbine blades rotate. The rotation moves a shaft connected to an electrical generator which converts the kinetic energy into electrical energy. The amount of energy produced mainly depends on the volume of water and the height difference between the water source and the turbines.
There are several types of hydroelectric facilities including:
- Impoundments use large reservoirs to restrict the flow of water and then kinetic energy is produced when the water is released.
- Run-of-river projects use the natural flow of waterways to produce kinetic energy.
- Pumped storage produces electricity by moving water between reservoirs at different elevations during peak times.
Conservation-based forest management
Conservation-based forest management is the use of long-term natural forest management practices to ensure forests continue to remove CO2 from the atmosphere. Deforestation is responsible for between 15 and 20% of global carbon emissions and the protection of our existing forests is essential to the reduction of carbon emissions around the world.
Activities include tending, thinning out, felling, regeneration/planting and fertilisation enabling the forest to grow as sustainably and productively as possible. Forests grown and protected in this way also improve wildlife habitat, biodiversity, water quality and sustainable economic development.
As forests grow the trees absorb or soak up CO2 from the atmosphere and sequester or hold it within their growing biomass (trunk, branches, leaves and root systems). This sequestered carbon stock is reliant on the forest remaining intact. Although some CO2 is released as the forest ‘breathes’, a forest that is growing and sustainable absorbs more carbon than it releases.
These forests are frequently covered by a conservation easement on the property which is a legal guarantee that the project’s carbon stocks remain protected through the project’s life and beyond through sustainable forest management.
In the unlikely event that a natural disturbance results in the loss of forest carbon, the easement terms enable the restoration of the forest and, as a result, carbon stocks.