What is our assessment?

The use of corn ethanol as a transportation biofuel, which has led to the expansion and intensification of corn production, does not reduce GHG emissions compared to gasoline. Based on this finding, using corn ethanol is not a plausible approach for reducing emissions and is “Not Recommended” as a climate solution.

What is it?

Corn ethanol is a liquid biofuel that is blended with gasoline to displace a fraction of the petroleum-based fuel with a renewable fuel derived from plants. Proponents claim that blending corn ethanol with gasoline reduces emissions because the CO₂ produced from combusting the ethanol is offset, or balanced out, by the atmospheric CO₂ absorbed by the corn plant during growth. Corn ethanol is made from corn grain by breaking down the starch in the kernels into sugar and then fermenting it into a liquid. In the United States, the world leader in biofuel production, almost 90% of biofuel is corn ethanol. Most gasoline now sold in the U.S. contains about 10% corn ethanol, and, in 2025, the Renewable Fuel Standard (RFS) program requires production of more than 15 billion gallons of this biofuel. Currently, it is primarily made from corn kernels; the technology for producing biomass-derived ethanol from other, non-edible parts of the corn plant is not yet commercially viable. Brazil is the second-largest producer of ethanol, but uses sugarcane as a feedstock. 

Does it work?

The Renewable Fuel Standard requires that the life cycle emissions from corn ethanol be at least 20% lower than those of conventional gasoline. However, based on comprehensive life cycle emissions analyses, using corn ethanol does not reduce emissions compared to gasoline. The main reasons for this are that the production of corn and processing it into ethanol generate large amounts of emissions, including from land conversion, fertilizer-related nitrous oxide emissions, and the industrial process of fermenting the corn into ethanol. The most prominent recent study reported that corn ethanol life cycle emissions were, at best, no less than gasoline and, more likely, were 24% higher. Corn ethanol is also more emissions-intensive than ethanol made from other plants, like sugar cane. 

Why are we excited?

Ethanol has been used as a transportation fuel, including as a blend with gasoline, for more than a century. It boosts the octane number of fuel, improves engine performance and fuel economy, and reduces emissions of harmful pollutants like unburned hydrocarbons, nitrogen oxides, and particulates. Ethanol has also been used to replace other harmful and polluting gasoline additives, including lead and methyl tert-butyl ether (MTBE). Ethanol produced from non-edible biological feedstocks with lower production emissions, such as switchgrass or cellulose from crop residues, has the potential to reduce emissions. 

Why are we concerned?

The Renewable Fuel Standard (RFS) program requires that biofuels be blended into the transportation fuel supply at annually increasing increments. The United States now uses one-third of its corn to generate more than 15 billion gallons of ethanol per year. Not only does this mandated program not reduce emissions (it more likely increases emissions), but it also consumes corn that could otherwise be used for food or animal feed. The increased demand for corn for ethanol has increased corn prices, which in turn have contributed to the conversion of grasslands and semi-natural ecosystems to grow more corn. When grasslands, woodlands, or other natural ecosystems are plowed and converted to cropland, the carbon stored in the vegetation and soil is emitted to the atmosphere. Between 2008 and 2016, the conversion of 1.8 Mha of natural and semi-natural land in the U.S. released about 400 million metric tons of CO₂ from vegetation and soil. The increased corn production also increased the application of synthetic fertilizers, which has increased nitrate leaching, phosphorus runoff, and emissions of nitrous oxide, a powerful GHG (see Improve Nutrient Management). These problems are particularly severe in the U.S. Midwest and the Mississippi River drainage.

What is our assessment?

Because incineration of waste to produce electricity and/or heat does not reduce emissions in most circumstances, and it can displace or disincentivize other, more effective waste treatment practices, Deploying Waste to Energy is “Not Recommended” as a climate solution.

What is it?

Waste to energy (WTE) uses high temperature incineration (above 800^oC) of waste, including municipal solid waste (MSW), medical or hazardous waste, and waste biomass from agriculture and forestry, to generate electricity and/or heat. This energy production technology can be used to displace fossil fuel energy sources. However, like fossil fuels, the incineration process produces GHGs during combustion, primarily CO₂ and nitrous oxides, as well as ash and other pollutants as byproducts. WTE also diverts waste from landfills and open dumps, avoiding high-impact methane emissions from decomposing organic materials and pollution and health risks from inorganic or toxic materials. Globally, there are more than 1,700 WTE plants. According to the International Energy Agency (IEA) World Energy Balances, WTE from industrial and municipal waste accounted for less than 0.5% of global energy production in 2022. Around 62% of WTE plants are in Asia, 33% are in Europe, and 4.5% are in North America. Other waste to energy technologies, such as pyrolysis and gasification, which use heat to convert organic materials into various forms of syngas, are evaluated in other Drawdown Explorer solutions and not included here. 

Does it work?

The effectiveness of WTE for reducing GHG emissions when substituting for fossil fuels for heat and energy, while also avoiding landfill emissions, is highly variable. Effectiveness varies with waste type and quality, combustion characteristics, air pollution controls, alternative disposal methods, and the type of electricity generation that it displaces. WTE incineration is less energy efficient than natural gas or coal for producing electricity (20–30% for WTE compared to 40–60%), and relatively more waste must be burned to produce comparable amounts of energy. WTE incineration is also less energy efficient than pyrolysis (40–75%), gasification (40–60%), and even methane digestion (30–40%). In regions that incinerate large proportions of plastic waste, such as South Korea and China, emissions are higher than for landfilling the waste. For some waste streams in some regions, other treatment strategies such as recycling, composting, pyrolysis, gasification, or the production of biochar, bio-oils, or bio-bricks yield greater emissions reductions.

Why are we excited? 

WTE can reduce waste volumes by up to 90%. In high-income regions without available land for sanitary landfills with landfill gas capture systems (see Improve Landfill Management), incineration is a viable alternative for post-recycling, hazardous, industrial, or medical waste. However, incineration of these waste streams requires strict standards, advanced air pollution control systems, and continuous monitoring to minimize harmful emissions of toxic pollutants. 

Why are we concerned?

In almost all circumstances, incinerating waste to produce reliable electricity or heat is not an effective method for reducing GHG emissions. WTE plants require a steady stream of waste feedstock to ensure ideal combustion conditions for electricity and heat production. This can incentivize waste production and disincentivize alternative waste treatments that reduce emissions more effectively. For example, in the European Union (EU), where incineration is widely used, some countries need to import waste to maintain energy production. This offsets some or all of the potential climate benefit due to emissions during transport and may divert attention from better waste management solutions, such as regulations on packaging, recycling, and composting. In other countries, high incineration rates of MSW (above 30%) are correlated with declines in recycling rates. For example, in 2018, Japan incinerated over 80% of MSW while only 4.9% was recycled. Recent policy initiatives there now focus on increasing recycling, which effectively and consistently reduces emissions, and decreasing incineration through source separation of waste. According to one study, chemically recycling plastic waste rather than incinerating it saves 0.82 kg CO₂‑eq /kg of feedstock. 

WTE is a substantial source of toxic air pollution. Poorly constructed, unregulated incinerators generate air pollution and large amounts of ash that will need further treatment. Advanced air pollution control systems are required to minimize emissions of GHGs and pollutants, including particulate matter, sulfur dioxide, nitrogen oxides, carbon monoxide, other acid gases, heavy metals, and persistent organic pollutants like dioxins. Even in high-income countries with strict air quality standards, polluting incinerators are disproportionately sited in under-resourced communities, which exacerbates environmental justice issues. In the United States, 79% of incinerators are located in low-income or minority communities. 

Finally, WTE is the most expensive waste management method in most regions, largely due to high capital costs. In 2018, all countries using industrial incinerators for incinerating more than 10% of MSW were high-income, except China. The addition of necessary emission control and monitoring systems further increases costs, making WTE more expensive than methane digesters or landfills with gas capture systems.

What is our assessment?

Using CCS on fossil-fueled power plants will reduce electricity production emissions, but it is more expensive, more energy-intensive, and more polluting than readily available, cheaper, and cleaner alternatives like wind, solar, and geothermal. Based on this, and the risk that large-scale deployment of CCS on fossil-fueled power plants could drive continued production and use of coal and gas, we conclude that using CCS on fossil fuel power plants is “Not Recommended” as a climate solution.

What is it?

Carbon capture and storage (CCS) is a technology that reduces GHG emissions from fossil fuel-powered electricity generation facilities by selectively capturing CO₂ from the power plant’s exhaust flue, preventing it from entering the atmosphere. The captured CO₂ is then concentrated, compressed, and permanently stored underground. There are other commercially available CCS technologies, such as pre-combustion capture and oxy-fuel combustion, but these are used almost exclusively for industrial processes like gas processing and cannot be readily retrofitted to existing power plants. CCS can also be applied to capture CO₂ from other industrial facilities that generate emissions from fuel combustion or production processes, like cement or ethanol production plants, or from biomass energy power plants. Instead of permanent storage, captured CO₂ can also be used as a chemical precursor for the manufacture of other products or for enhanced oil recovery, but, compared with geologic storage, these post-capture uses of CO₂ emit GHGs, thereby reducing or eliminating the emissions reduction efficacy of CCS. 

Does it work?

The technology and chemistry for the selective capture of CO₂ from the exhaust of a power plant are effective. There are numerous chemical, membrane, and cryogenic methods for capturing CO₂, but monoethanolamine (MEA) is the predominant commercially available chemical absorbent currently in use in power plants with CCS. CO₂ capture efficiency varies with the type of reactive absorbent material and plant operations. Most CCS installations target 90% CO₂ capture rates, although actual capture rates are usually lower. CCS infrastructure is large, and the process of capturing CO₂ from power plant exhaust is complex, expensive, and energy-intensive. CCS requires the flue gas to be pumped to different parts of the power plant, the CO₂ to be captured and then separated from the sorbent material, and the concentrated CO₂ to be compressed for transport and storage. Energy for all these processes comes from the power plant. Various studies estimate CCS consumes at least 15–25% of the plant’s total generation capacity, with most of the energy used to separate the CO₂ and regenerate the sorbent material. 

CCS has been used in pilot studies and commercial operations in a few dozen coal and natural gas power plants since the late 1990s. Despite the functional effectiveness of the technology, use of CCS to reduce power plant emissions has not been broadly adopted, and most CCS projects initiated in the past three decades have failed or been discontinued. Based on various assessments and projections, deployment of CCS on power plants has consistently lagged behind its expected contribution to emissions reduction. There are currently only four power plants with CCS in operation in the world, less than 0.05% of the global fossil-fueled power plant fleet. According to a 2021 study, only 10% of proposed CCS projects for power plants have actually been implemented. Based on another study, 78% of all power plant and industrial manufacturing CCS pilot and demonstration plants with a project size greater than 0.3 Mt CO₂ /yr have been cancelled or put on hold. 

Why are we excited?

Globally, emissions from coal- and gas-fired power plants are still increasing, primarily in China and India, where large numbers of new thermal power plants have been built in the last two decades. Given the typical 30- to 45-year operational lifespan for coal and gas power plants, retrofitting these newer plants with CCS could substantially reduce their operational emissions while also allowing plant owners and investors to recover their investments. Installation of CCS to reduce emissions can also be prioritized for power plants located near places with geologic storage and where alternative electricity generation options are limited. There is a large amount of research underway to develop and test alternative carbon capture technologies, most aimed at increasing carbon capture efficiencies and reducing energy demands and costs. Other research on the factors contributing to the failure of most CCS projects to date may lead to the development of regulations and policies that require or incentivize the use of CCS for power plants, which could increase the current low implementation and success rates for this emissions reduction technology. 

Why are we concerned? 

While CCS can reduce the operational CO₂ emissions from fossil-fueled power plants, large-scale deployment of this technology will likely drive continued production and use of coal and gas. Even before fossil fuels are burned, extraction, transport, and processing generate substantial GHG emissions, particularly for gas. Therefore, in addition to perpetuating the fossil fuel industry, even 90% efficient CCS reduces only a fraction of the life cycle emissions from coal and gas. 

Widespread deployment of CCS in the electricity sector could also delay or crowd out deployment of wind, solar, and geothermal energy, slowing the clean energy transition that is already underway. Beyond these risks, the three-decade-long failure of power plant CCS to make the transition from pilot-scale science and technology to large-scale commercial deployment reflects its systemic problems and limitations. Unlike wind and solar energy, which have seen costs decline rapidly with development and deployment, CCS on power plants shows little evidence of a learning curve. It remains very expensive and very energy-intensive. A large-scale CCS demonstration project can cost more than US$1 billion to build and, in addition to its operational costs, CCS consumes at least 15–25% of the energy that the plant could otherwise sell to customers. CCS-related energy requirements could mean that a power company would need to build an additional power plant to compensate for reduced electricity deliveries from every four of its power plants equipped with CCS. 

Due to these high project risks and costs, as well as the lack of regulations and policies to require or support CCS on power plants, public and private investments in the technology have been falling. Despite all this, recent research shows that the vast majority of lobbying spending for government support of CCS comes from fossil fuel interests, which have publicly stated that they view the technology as a strategy to extend society’s use of fossil fuels. Finally, in contrast to most other climate solutions that provide other benefits to natural systems or human well-being, CCS on power plants does nothing to address or alleviate the current harm from toxic air pollution produced by fossil-fueled power plants.