Cut Emissions Industry, Materials & Waste Improve Materials

Improve Cement Production

Highly Recommended
Cement factory

Cement is a key ingredient of concrete, a manufactured material used in massive quantities around the world. Cement production generates high CO₂ emissions from the production of clinker, a binding ingredient. These emissions come from not only the chemical reaction that produces clinker, but also burning fossil fuels to provide heat for this reaction. We define the Improve Cement Production solution as reducing GHG emissions related to cement manufacturing by substituting other materials for clinker, using alternative fuels, and improving process efficiency.

Last updated June 30, 2025

Solution Basics

Mt clinker avoided/yr

tCO2-eq/unit
690,000
units
Current 9801,0002,000
Achievable (Low to High)

Climate Impact

GtCO2-eq/yr
Current 0.67 0.71
US$ per tCO2-eq
-30
Gradual

CO₂

Solution Basics

Mt cement produced using alternative fuels/yr

tCO2-eq/unit
96,000
units
Current 3006102,000
Achievable (Low to High)

Climate Impact

GtCO2-eq/yr
Current 0.03 0.060.2
US$ per tCO2-eq
-50
Gradual

CO₂

Solution Basics

GJ thermal energy input/yr reduced

tCO2-eq/unit
0.08
units
Current 08.86×10⁸1.18×10⁹
Achievable (Low to High)

Climate Impact

GtCO2-eq/yr
0.080.1
US$ per tCO2-eq
-60
Gradual

CO₂

Additional Benefits

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Overview

Concrete production requires the manufacturing of 4 Gt of cement annually (U.S. Geological Survey, 2024). Roughly 85% of cement industry GHG emissions come from the production of a key cement component called clinker. Both the clinker formation chemical reaction and fuel combustion for high-temperature clinker kilns release GHGs (Goldman et al., 2023). Figure 1 illustrates the manufacturing steps responsible for these emissions and highlights how three approaches – clinker material substitution, use of alternative fuels, and process efficiency upgrades – could mitigate emissions.

Figure 1. Cement production GHG emissions. Some 85% of GHGs emitted during cement production are released when clinker is produced in high-temperature kilns. The three approaches analyzed in this solution – clinker material substitution, alternative fuels, and process efficiency upgrades – aim to mitigate such emissions. Modified from Goldman et al. (2023).

Diagram of energy used in cement production process

Source: Goldman, S., Majsztrik, P., Sgro Rojas, I., Gavvalapalli, M., Gaikwad, R., Feric, T., Visconti, K., & McMurty, B. (2023). Pathways to commercial liftoff: Low-carbon cement. U.S. Department of Energy. https://liftoff.energy.gov/wp-content/uploads/2023/09/20230918-Pathways-to-Commercial-Liftoff-Cement.pdf 

Clinker material substitution replaces a portion of the clinker used in cement with alternative materials, thus reducing the amount of clinker manufactured. This decreases the amount of CO₂ emitted by the chemical reaction and fuel combustion. Clinker is made by heating limestone to convert it to lime. This reaction releases CO₂. Some of the CO₂ production can be eliminated by replacing some of the clinker with substitute materials such as industrial waste products, other cementitious compounds, or available minerals. Clinker material substitution also reduces energy demand, lowering emissions from burning fossil fuels. Clinker fraction in cement is often expressed as a clinker-to-cement ratio, which ranges from 0 (no clinker) to 1 (entirely clinker). The most common type of cement, Portland cement, typically has a clinker-to-cement ratio of 0.95, meaning the cement is 95% clinker by mass.

Alternative fuels that can be used to heat cement kilns in place of fossil fuels are typically biomass and waste-based fuels. Cement production uses two kilns, one heated to ~700 °C and the other to ~1,400 °C (U.S. Department of Energy, 2022). The energy needed to provide this heat typically comes from burning fossil fuels such as oil, gas, coal, and petroleum coke on-site, which emits CO₂ as well as small amounts of other GHGs, including methane and nitrous oxide, and air pollutants, including nitrogen oxides, sulfur oxides, and particulate matter (Hottle et al., 2022; Miller & Moore, 2020). Switching to alternative fuels decreases emissions by reducing the mining and combustion of fossil fuels and recovering energy from waste streams that would have otherwise released GHG during decomposition or incineration (Georgiopoulou & Lyberatos, 2018).

Process efficiency upgrades include a broad suite of technologies such as improved controls, electrically efficient equipment (e.g., mills, fans, and motors), thermally efficient and multistage kilns, and waste heat recovery. These improvements lead to less wasted heat and input energy, and therefore require less fossil fuel burning during manufacturing. In particular, upgrading kilns has the potential for high emissions mitigation (Mokhtar & Nasooti, 2020; Morrow III et al., 2014). Kiln upgrades can include processing dry raw material (which is more efficient than expending energy to remove moisture from wet feedstock), adding a preheater that uses kiln exhaust gas to dry and preheat raw material, and adding a precalciner kiln that uses some of the fuel to partially calcinate raw material at a lower temperature (European Cement Research Academy, 2022; Schorcht et al., 2013). Each study included in our analysis for effectiveness and cost included a set group of technologies that were considered to be process efficiency upgrades.

The cost and avoided emissions from each approach vary depending on the other technologies in use at a particular cement plant (Glenk et al., 2023). While coupling the impacts of the approaches would provide the most accurate representation of this solution, that analysis is complex and outside the scope of this assessment. Therefore, we will consider the three approaches separately. 

5.42%
of total global emissions
4.1 Billion

Worldwide, we make 4.1 billion metric tons of cement every year.

3.2 Gt

In the process, we produce more than 3 Gt CO₂‑eq of greenhouse gases – 5.42% of global annual emissions

Impact Calculator

Adjust effectiveness and adoption using range sliders to see resulting climate impact potential.

Effectiveness

690,000
t CO2-eq/Mt clinker avoided, 100-yr basis
25th
percentile
540,000
75th
percentile
860,000
690,000
median

Adoption

980
Mt clinker avoided/yr
Low
1,000
High
2,000
980
current
Achievable Range

Climate Impact

0.676
Gt CO2-eq/yr (100-yr)
06 Gt
1.144%
of total global emissions*
*59.09 Gt CO2-eq/yr (100-yr basis)
Adjust effectiveness and adoption using range sliders to see resulting climate impact potential.

Effectiveness

96,000
t CO2-eq/Mt cement produced, 100-yr basis
25th
percentile
77,000
75th
percentile
99,000
96,000
median

Adoption

300
Mt cement produced using alternative fuels/yr
Low
610
High
2,000
300
current
Achievable Range

Climate Impact

0.029
Gt CO2-eq/yr (100-yr)
06 Gt
0.049%
of total global emissions*
*59.09 Gt CO2-eq/yr (100-yr basis)
Adjust effectiveness and adoption using range sliders to see resulting climate impact potential.

Effectiveness

0.0847
t CO2-eq/GJ thermal energy reduced, 100-yr basis

Adoption

0
GJ thermal energy input/yr reduced
Low
8.86×10⁸
High
1.18×10⁹
0
current
Achievable Range

Climate Impact

0.000
Gt CO2-eq/yr (100-yr)
06 Gt
0.000%
of total global emissions*
*59.09 Gt CO2-eq/yr (100-yr basis)

Maps

There are no location-specific constraints to the effectiveness of the Improve Cement Production solution as there are for solutions dependent on climatic factors. However, there is geographic variation associated with current uptake of solutions and feasibility/expense of future uptake. Moreover, the distribution of cement-producing facilities around the world is non-uniform, thus the solution set naturally has the greatest applicability in regions with the greatest concentration of cement production. China and India have particularly high production of cement at 51% and 8% of global totals in 2024, respectively (Sinha & Crane, 2024).

Newer cement plants are more likely to have high thermal efficiencies, and the age of cement plants varies around the world, with average ages of cement plants less than 20 years in much of Asia, and greater than 40 years in much of the US and Europe.

Uptake of alternative fuels is relatively high in Europe and low in the Americas.  

While use of clinker substitutes is in principle possible anywhere, the materials themselves are not readily available everywhere, thus transportation costs and associated emissions can place constraints on their viability (Shah et al., 2022).

Mt CO2-eq
< 2
2 - 4
4 - 6
6 - 8
8 - 10
> 10

Annual cement plant emissions, 2024

Cement production is responsible for approximately 4% of global GHG emissions. This is partly due to burning fossil fuels to run kilns and partly due to CO2 emissions associated with the chemistry of producing clinker, a key component of cement.

Sinha, A. and Crane, V. (2024). Manufacturing and industrial processes sector: Cement manufacturing emissions [Data set]. TransitionZero, Climate TRACE Emissions Inventory. Retrieved February 11, 2025, from https://climatetrace.org

Mt CO2-eq
< 2
2 - 4
4 - 6
6 - 8
8 - 10
> 10

Annual cement plant emissions, 2024

Cement production is responsible for approximately 4% of global GHG emissions. This is partly due to burning fossil fuels to run kilns and partly due to CO2 emissions associated with the chemistry of producing clinker, a key component of cement.

Sinha, A. and Crane, V. (2024). Manufacturing and industrial processes sector: Cement manufacturing emissions [Data set]. TransitionZero, Climate TRACE Emissions Inventory. Retrieved February 11, 2025, from https://climatetrace.org

The Details

Current State

Our analysis of the current state of solutions for improved cement production included three separate approaches to reducing emissions: clinker material substitution, alternative fuels, and process efficiency upgrades. Each approach had adoption units chosen based on data availability and consistency between calculated values. Figure 2 summarizes the units and conversions used for all approaches (Habert et al., 2020).

Figure 2: Units of quantification used in the Current State, Adoption, and Impacts analyses below.

Approach Clinker material substitution Alternative fuels Process efficiency upgrades
Effectiveness

t CO₂-eq abated/Mt clinker avoided*

t CO₂ abated/Mt cement produced*

 t CO₂-eq abated/Mt cement produced

t CO₂-eq abated/GJ thermal energy input**

t CO₂-eq abated/Mt cement produced**
Cost US$/Mt cement produced US$/Mt cement produced US$/Mt cement produced
Adoption Mt clinker avoided/yr Mt cement/yr produced using alternative fuels GJ thermal energy input saved/yr
Climate impact Gt CO₂-eq/yr Gt CO₂-eq/yr Gt CO₂-eq/yr

*Clinker material substitution effectiveness was calculated in two different adoption units using the same source data. Effectiveness in t CO₂‑eq abated/Mt cement produced was used to calculate cost per climate impact. Effectiveness was converted to t CO₂‑eq abated/Mt clinker avoided using the clinker-to-cement ratio for each individual study in the analysis, and this was used to calculate climate impact.

**Process efficiency upgrades effectiveness in units of t CO₂‑eq abated/Mt cement produced was used to calculate cost per climate impact. Separately, a calculated fuel emission factor effectiveness in units of t CO₂‑eq abated/GJ thermal energy was used to quantify climate impact.

Cement production currently emits 760,000 t CO₂‑eq /Mt cement produced, based on our analysis. With global cement production exceeding 4 Gt/yr (U.S. Geological Survey, 2024), the scale of emissions to be mitigated is large.

Clinker material substitution is the most effective of the three approaches at reducing emissions, eliminating approximately 240,000 t CO₂‑eq /Mt cement produced. This is equivalent to 690,000 t CO₂‑eq /Mt clinker avoided (Table 1a). This estimate is based on expert predictions of GHG savings for realistic target levels of clinker replacement with material substitutes.

Alternative fuels and process efficiency upgrades ) have carbon abatement potentials of 96,000 and 90,000 t CO₂‑eq /Mt cement produced, respectively, when calculated based on production levels (Table 1b). Since the units of adoption for process efficiency upgrades are GJ thermal energy input, when calculating climate impact we used an effectiveness per GJ of thermal energy, calculated using an emission factor for fuel combustion. This effectiveness is 0.0847 t CO₂ /GJ thermal energy input (Table 1c) (Gómez & Watterson et al., 2006; IEA, 2023c). 

We calculated the effectiveness of these three approaches separately. Because the implementation of each affects the effectiveness potential of the others (Glenk et al., 2023), the actual effectiveness will be lower when the approaches are implemented together.

Emissions reductions from these approaches can be directly related to how the approach impacts GHG emissions from clinker production and fossil fuel burning. However, sourcing, processing, and transporting clinker substitutes and alternative fuels also produces GHGs. Our data sources did not always report whether such indirect emissions were accounted for, so our analysis primarily focuses on direct emissions. Further analysis of other life-cycle emissions considerations would be valuable in future research; however, indirect emission levels for both clinker substitutes and alternative fuels are reportedly small compared to direct emissions (European Cement Research Academy, 2022; Shah et al., 2022).

Additionally, cement industry members sometimes assume that there are no direct emissions from burning biomass fuels (Goldman et al., 2023). As a result, we assume that direct emissions from biomass are not fully accounted for in the data and therefore that the climate benefit of using alternative fuels may be exaggerated.

While other GHGs, including methane and nitrous oxide, are also released during cement manufacturing, these gases represent a small fraction (<3% combined) of overall CO₂‑eq emissions so we considered them negligible in our calculations (U.S. Environmental Protection Agency, 2016; Hottle et al., 2022). 

Table 1. Effectiveness at reducing emissions.

Unit: t CO₂‑eq /Mt cement produced (100-year basis)

25th percentile 540,000
mean 710,000
median (50th percentile) 690,000
75th percentile 860,000

Unit: t CO₂‑eq /Mt cement produced (100-year basis)

25th percentile 77,000
mean 94,000
median (50th percentile) 96,000
75th percentile 99,000

Unit: t CO₂‑eq /Mt cement produced (100-year basis)

calculated value 0.0847

All three approaches to mitigating cement emissions result in cost savings by our analysis. Despite high initial costs, when considering the long technology lifetime and annual operational savings, the net lifetime and annualized costs are lower than conventional cement production.

Clinker material substitution has the highest net savings of the three approaches, with US$7 million/Mt cement produced generating savings of US$30/t CO₂‑eq . While initial and operating costs may vary between different substitute materials, we averaged all material types for each cost estimate. Goldman et al. (2023) and the European Cement Research Academy (2022) offer breakdowns of cost by material type.

Alternative fuels generate savings of US$5 million/Mt cement, or US$50/t CO₂‑eq mitigated. For both clinker material substitution and alternative fuels, cost and emissions will vary based on local material availability (Cannon et al., 2021). We assumed equivalent costs for all alternative fuel types.

Process efficiency upgrades save US$6 million/Mt cement and have the highest cost savings per unit climate impact (US$60/t CO₂‑eq ). While process efficiency upgrades encompass many different technologies, this cost estimate incorporates the costs of two of the technologies yielding high avoided emissions – replacing long kilns with preheater/precalciner kilns and implementing efficient clinker cooler technology. Between these technologies, upgrading to preheater/precalciner kilns represents most of the initial cost increase and the operational cost savings (European Cement Research Academy, 2022).

The costs of each approach (Table 2) were calculated as amortized initial costs of upgrading plants, added to the expected changes in annual operational costs. Only very limited data are available for price premiums on low-carbon cement. Therefore, we did not include any revenues for low-carbon cement. 

While we calculated these costs separately, in reality the cost for implementing multiple approaches will be different due to interactions between technologies (Glenk et al., 2023). For example, material processing equipment could change based on the type of clinker substitute materials. We do not expect the costs to be additive as we assumed in our analysis, and limited cost data means that this estimate is based on limited sources.

Table 2: Cost per unit climate impact.

Unit: 2023 US$/t CO₂‑eq (100-yr basis)

Clinker material substitution -30
Alternative fuels -50
Process efficiency upgrades -60

Negative values reflect cost savings.

The technologies needed for all approaches in this solution are well developed and ready to deploy at scale, so we did not consider learning curves. 

We did not find any global data on cost changes related to adoption levels for equipment, including energy-efficient processing technologies, dry-process kilns, or material storage. A portion of the solution’s initial costs come from plant downtimes, which would not be impacted by the technology learning curve. For feedstock components of the solution, including alternative fuels and clinker material substitutes, the costs will be subject to material availability, market prices, and transportation, and therefore will not necessarily decrease with adoption.

Speed of action refers to how quickly a climate solution physically affects the atmosphere after it is deployed. This is different from speed of deployment, which is the pace at which solutions are adopted.

At Project Drawdown, we define the speed of action for each climate solution as gradual, emergency brake, or delayed.

Improve Cement Production is a GRADUAL climate solution. It has a steady, linear impact on the atmosphere. The cumulative effect over time builds as a straight line.

Adoption

Few global data are available for current adoption. Most data are from regional sources, typically the United States or Europe. As a result, we do not expect these data to be representative at the global level – China and India alone produce more than 60% of the world’s cement (U.S. Geological Survey, 2024). Therefore, we quantified adoption only from a limited number of worldwide sources, using the adoption units listed in Figure 2.

Clinker material substitution is challenging to assess for adoption, since it is implemented with a broad range of materials and replacement fractions. We therefore simplified adoption in this analysis by quantifying it as the amount of global cement material that is not clinker. The adoption tonnage (Table 3a) represents Mt of clinker production avoided, using conventional Portland cement (5% non-clinker) as a baseline (CEMBUREAU, n.d.). Note that this is different from the way we considered cement tonnage for effectiveness and cost. There, we calculated emissions reductions for a Mt of cement produced including substituted material. For adoption, however, we considered tonnage to be clinker avoided (based on amount replaced with other materials).

The IEA (2023a) and the European Cement Research Academy (2022) estimated the global clinker-to-cement ratio to be approximately 0.72, meaning that 28% of cement composition is material other than clinker. This correlates to 980 Mt clinker avoided/yr used over the Portland cement baseline.

Alternative fuels are currently used to replace approximately 7% of fossil fuels in global cement production (Global Cement and Concrete Association, 2021; IEA, 2023c). We assumed this means approximately 300 Mt cement/yr are currently produced with biomass and waste fuels (Table 3b).

Process efficiency upgrades encompass dozens of technological improvements, which – along with a paucity of available data – make adoption levels challenging to assess. To estimate the current state of energy usage in the cement industry, we used the IEA (2023c) estimate of 3,550,000 GJ/Mt clinker as the 2022 benchmark thermal energy input for clinker production. This value does not include electrical efficiency and can vary based on fuel mix, but approximates the current state of energy use. We converted it to GJ/yr using amounts of annual clinker production, yielding 10.5 billion GJ thermal energy consumed each year for clinker production. Since there is no baseline for efficiency, we consider this value to be the zero adoption scenario and 0 GJ/yr are saved (Table 3c).

For the other approaches, there is a clear baseline case of “zero adoption” where no substitutes or alternative fuels are in use. However, thermal energy input is an energy use indicator that represents a continuum with no clear baseline. We therefore had to benchmark future energy savings against an initial value, which we chose as 2022 since it provided the most recent available data. All future estimates represent annual GHG savings relative to global cement production’s 2022 GHG emissions levels.

Table 3. Current adoption level (2022).

Unit: Mt clinker avoided/yr

median (50th percentile) 980

Unit: Mt cement produced using alternative fuels/yr

median (50th percentile) 300

Unit: GJ thermal energy input/yr saved

median (50th percentile) 0

Clinker material substitution has experienced relatively unchanged adoption worldwide in recent years (Table 4a). Since 2016, there has been a small increase in clinker-to-cement ratio, indicating a slight decrease in adoption of this approach (IEA, 2023a). This corresponds to 40 Mt fewer clinker material substitutes being used each year, on average. 

Alternative fuels adoption is slowly on the rise as percent of fuel mix (Table 4b). According to the IEA (2023c), the percentage of global clinker produced by bioenergy and waste fuels increased from 6.5% in 2015 to 8.5% in 2022. This corresponds to a median annual increase of 12 Mt cement/yr produced by alternative fuels. 

The IEA (2023c) reported process efficiency upgrades to have led to a median annual decrease of 5,000 GJ/Mt clinker from 2011 to 2022, representing a –0.14% annual change in energy input. This indicates that processes consuming thermal energy have become slightly more efficient in recent years. When converted to GJ/yr, this is 15 million fewer GJ thermal energy consumed each year (Table 4c).

Table 4. Adoption trend.

Unit: change in Mt clinker avoided/yr

median (50th percentile) –40

2016–2022 adoption trend

Unit: change in Mt cement produced using alternative fuels/yr

median (50th percentile) 12

2015–2022 adoption trend

Unit: annual change in GJ thermal energy input/yr

median (50th percentile) -15,000,000

2011–2022 adoption trend

The adoption ceiling (Table 5a, Table 5b, Table 5c) is high for all approaches within this solution.

Clinker material substitution adoption is likely to be limited primarily by material standards and availability. Across literature, the median adoption ceiling is considered to be 3,000 Mt clinker avoided/yr beyond the Portland cement baseline, yielding a clinker-to-cement ratio of 0.2. Snellings (2016) calculated the worldwide amount of clinker materials substitutes and found that a maximum of ~2,000 Mt/yr would be available, which would result in a clinker-to-cement ratio of approximately 0.5. In the future, some waste materials – like fly ash and ground granulated blast furnace slag – are likely to be less available so increasing the possible substitute amounts would require research on new materials or cement properties.

Alternative fuels are typically assumed to be applicable to roughly 90% of cement production globally, or approximately 4,000 Mt cement/yr at 2022 global production levels (Daehn et al., 2022). In theory, kilns can use 100% alternative fuels, although composition of the fuel can influence the trace elements or calorific value (European Cement Research Academy, 2022). In particular, several analyses point to the lower calorific value of alternative fuels as an adoption-limiting factor. Cavalett et al. (2024) considered 90% to be the maximum. A separate analysis of Canadian cement production determined that 65% is the threshold due to lower-calorie fuels only being applicable in a precalciner kiln – the equipment where fuel is used to begin decomposing limestone through the calcination process (Clark et al., 2024).

Process efficiency upgrades have their adoption ceiling limited by the minimum thermal energy demand needed to run cement kilns. The European Cement Research Academy estimates this lower threshold of energy input to be approximately 2,300,000 GJ/Mt clinker, considering chemical reaction and evaporation energy needs (European Cement Research Academy, 2022). This converts to 6.9 billion GJ thermal energy used each year, or 3.6 billion GJ/yr saved over current thermal energy efficiency levels (Table 5c).

Table 5. Adoption ceiling.

Unit: Mt clinker avoided/yr

median (50th percentile) 3,000

Unit: Mt cement produced using alternative fuels/yr

median (50th percentile) 4,000

Unit: GJ thermal energy input/yr saved over current levels

median (50th percentile) 3,600,000,000

Lower limit for energy input

Clinker material substitution achievable adoption (Table 6a) is primarily limited by material availability and initial costs. Global estimates generally expect 30–50% of total substituted material to be reasonable, which correlates to a clinker-to-cement ratio of 0.4–0.6 and 1,000–2,000 Mt clinker avoided/yr (Habert et al., 2020; European Cement Research Academy, 2022). In a separate U.S.-specific analysis, the substitute amount was projected to vary from 5% to 45% depending on the availability and performance of the material substitute (Goldman et al., 2023).

Alternative fuels are projected to account for roughly 40% of the cement fuel mix in 2050 for both global and North American estimates. Taking the median of the global achievable adoption estimates, this correlates to 2,000 Mt cement/yr that would be produced using alternative kiln fuels. As a low estimate, if the current adoption trend holds, approximately 16% of global cement fuel (producing 610 Mt cement/yr) will come from biomass and waste (IEA, 2023c). A reasonable adoption range is 610–2,000 Mt cement/yr (Table 6b), although some European countries currently have ~80% adoption of alternative fuels, meaning that >40% adoption in an aggressive 2050 scenario may be feasible (Cavalett et al., 2024).

Little information exists on projected global adoption of process efficiency upgrades between now and 2050. In an analysis of a fraction of cement plants in China, India, and the U.S., it was estimated that these three countries – which represent more than 70% of current cement production worldwide – could reach a thermal energy input of 3.15–3.25 million GJ/Mt clinker by 2060, or 9.30–9.59 billion GJ/yr, which is 0.886–1.18 billion GJ/yr saved over current adoption levels (Table 6c; Cao et al., 2021). Meanwhile, in a European analysis, the European Cement Research Academy found the same range to be possible by 2050 (European Cement Research Academy, 2022). This is not significantly lower than the current state due to the fact that the highest-producing countries – China and India – have newer manufacturing facilities with more efficient equipment today. Countries with more room to improve in thermal energy efficiency – such as the U.S. – produce only a small fraction of the world’s cement. Approximately 92% of global plants are estimated to use more efficient dry kiln technology, indicating that some of the more energy-saving equipment upgrades are already highly adopted (Isabirye & Sinha, 2023). Therefore, there is less room for increased adoption in kiln technologies worldwide, although electrical efficiency measures could further improve these values.

 While the estimates for tonnage of cement impacted by these approaches are based on 2022 global production numbers, cement production will change through 2050, meaning the impacted mass of cement will also change as these emissions-reducing measures are adopted (IEA, 2023b).

Table 6. Range of achievable adoption levels.

Unit: Mt clinker avoided/yr

Current Adoption 980
Achievable – Low 1,000
Achievable – High 2000
Adoption Ceiling 3000

Unit: Mt cement produced using alternative fuels/yr

Current Adoption 300
Achievable – Low 610
Achievable – High 2,000
Adoption Ceiling 4,000

Unit: GJ thermal energy input/yr saved over current adoption levels

Current Adoption 0
Achievable – Low 886,000,000
Achievable – High 1,180,000,000
Adoption Ceiling 3,600,000,000

Note: High adoption in this case results in lower energy use for each unit of clinker produced, and thus better efficiency. 

Impacts

Improved cement production has high potential for climate impact. Since cement production is responsible for 7–8% of global GHG emissions, mitigating even a portion of these emissions will meaningfully reduce the world’s carbon output. 

Clinker material substitution has the highest current and potential GHG emissions savings of the three approaches (Table 7a). To calculate the climate impact, we used effectiveness and adoption on the basis of Mt clinker avoided. Climate impact was calculated as:

CO₂ abatedyear =CO₂ abatedclinker avoidedx  clinker avoidedyear 

  • Current GHG savings: 0.67 Gt CO₂‑eq/yr
  • GHG savings ceiling: 2 Gt CO₂‑eq/yr
  • Achievable GHG savings range: 0.7–1 Gt CO₂‑eq/yr

Alternative fuels have a low current climate impact but possess the potential to be adopted for a much greater fraction of the global kiln fuel mix (Table 7b). However, alternative fuels’ potential GHG emissions savings are lower than those for clinker material substitutes because alternative fuels have a lower CO₂ mitigation effectiveness. Climate impact is calculated as:

CO₂ abatedyear =CO₂ abatedcement producedx  cement producedyear 

  • Current GHG savings: 0.03 Gt CO₂‑eq/yr
  • GHG savings ceiling: 0.4 Gt CO₂‑eq/yr
  • Achievable GHG savings range: 0.06–0.2 Gt CO₂‑eq/yr

Process efficiency upgrades are the most challenging to assess for climate impact because they represent a broad range of equipment upgrades with no clear baseline efficiency. We considered adoption to be energy savings from the current (2022) baseline in GJ thermal energy input/yr. We converted adoption to climate impact using the emission factor of 0.0847 t CO₂‑eq /GJ thermal energy input (calculated using data from Gómez & Watterson et al., 2006 and IEA, 2023c). The resulting calculation is as follows:

CO₂ abatedyear =CO₂ emissionsthermal energyx  thermal energy savings from 2022 baselineyr 

  • Current GHG savings: N/A (we consider the current adoption to be the baseline)
  • GHG savings ceiling: 0.31 Gt CO₂‑eq/yr less than 2022
  • Achievable GHG savings range: 0.0760–0.101 Gt CO₂‑eq/yr less than 2022

While clinker material substitution, alternative fuels, and process efficiency upgrades are quantified separately here, the adoption of any of these approaches will reduce the climate impact of the others. In particular, the climate impacts for technologies that reduce emissions per Mt of clinker (such as alternative fuels and process efficiency upgrades) will be lower when implemented along with technologies that reduce the amount of clinker used (such as clinker material substitution), and vice versa (Glenk et al., 2023). Therefore, these impacts will not be additive, although they will contribute to reduced emissions when implemented together.

While our analysis found clinker material substitution to have the highest climate impact, cement manufacturers will have to prioritize these technologies depending on their plant’s existing equipment, local availability of materials, and regional cement standards.

Table 7. Climate impact at different levels of adoption.

Unit: Gt CO₂‑eq/yr, 100-yr basis

Current Adoption 0.67
Achievable – Low 0.7
Achievable – High 1
Adoption Ceiling 2

Unit: Gt CO₂‑eq/yr, 100-yr basis

Current Adoption 0.03
Achievable – Low 0.06
Achievable – High 0.2
Adoption Ceiling 0.4

Unit: Gt CO₂‑eq/yr, 100-yr basis

Current Adoption N/A
Achievable – Low 0.075
Achievable – High 0.100
Adoption Ceiling 0.31

The main non-climate benefits of improved cement production are reduced air pollution and improved public health.

Air Quality 

Cement production is a major contributor to air pollution. Globally, concrete production accounts for approximately 8% of nitrogen oxide emissions, 5% of sulfur oxide emissions, and 5% of particulate matter emissions, with a significant portion of all these emissions stemming exclusively from cement production (Miller & Moore, 2020). Cement-related air pollution is especially acute in China, which produces over 50% of the world’s cement (U.S. Geological Survey, 2024). In 2009, China's cement industry emitted 3.59 Mt of particulate matter, making the industry the leading source of particulate matter emissions in the country (Yang et al., 2013). China also released 0.88 Mt of sulfur dioxide, accounting for about 4% of the national total, and emitted 1.7 Mt of nitrogen oxides (Yang et al., 2013). Process efficiency upgrades in cement manufacturing can reduce these harmful emissions. For example, implementing energy efficiency measures in China’s cement industry could reduce particulate matter by more than 3%, lower sulfur dioxide emissions by more than 15%, and decrease nitrogen oxide emissions by more than 12% by 2030 (Zhang et al., 2015). In Jiangsu province, which is the largest cement producer in China, energy and CO₂ reduction techniques could cut particulate matter and nitrogen oxide emissions by 30% and 56%, respectively, by 2030 (Zhang et al., 2018).

Health 

Miller & Moore (2020) estimated that the health damages associated with cement production amounted to approximately US$60 billion globally in 2015. These health damages are due to air pollutants produced during cement manufacturing, which would be reduced by this solution as described above. In China, one study estimated that improving energy efficiency in the Jing Jin Ji region’s cement industry could prevent morbidity in 17,000 individuals (Zhang et al., 2021). 

Other

Manufacturing emissions reductions due to clinker material substitution, alternative fuels, and process efficiency upgrades are both permanent and additional. 

Permanence 

There is a low risk that the emission reductions this solution generates will be reversed in the next 100 years. This approach calls for reduced burning of fossil fuels and less calcination of limestone into clinker, thereby avoiding emissions from these activities. Meanwhile, carbon that is not released as CO₂ due to these technologies will remain stable in limestone or fossil fuel reserves indefinitely, making the emissions mitigation permanent.

Additionality 

These cement emissions reductions are additional if they are adopted in amounts higher than what is currently required and used in local or regional cement manufacturing. Afsah (2004) assessed additionality based on whether it represents “not common practice” from a national standpoint of market share or adoption. ClimeCo (2022) suggested that for clinker material substitutes to be considered additional, the substitute needs to meet two criteria: The replacement is not mandated by law, and new or emerging materials are used.

According to the U.S. Federal Highway Administration (n.d.), the use of clinker material substitutes in cement slows concrete curing times. Additionally, some clinker material substitutes, such as fly ash, raise ecotoxicity concerns and require safe handling (U.S. Department of Energy, 2022). Robust research and development is needed for new compositions of cement to accelerate testing, standardization, and adoption (Griffiths et al., 2023). Since regional standards vary for cement and concrete, policy and regulatory support designed for specific locations will be necessary to influence adoption levels and rates.

Most clinker material substitutes have limited or regional availability, leading to shortages, high costs, and transportation emissions (Habert et al., 2020). Because some substitute materials are sourced from the waste streams of other industries, such as the coal and steel industries, the long-term feasibility of sourcing these materials is uncertain (Goldman et al., 2023; Juenger et al., 2019). However, one study found that most leading cement-producing countries have substitute materials available in sufficient quantities to replace at least half of their current clinker usage (Shah et al., 2022). 

In terms of risks associated with alternative fuels, they can be subject to regional scarcity. Lack of available waste fuel in particular could risk non-waste biomass burning, leading to deforestation and high net emissions (de Puy Kamp, 2021). In addition, waste fuels can have varying compositions that can lead to different heats of combustion, kiln compatibility, or emitted pollutants (Griffiths et al., 2023). Finally, the use of waste products requires cement plants to be situated near industrial waste sources, risking low adoption for cement plants that are not located near a waste source. 

Wider adoption of clinker material substitutes, alternative fuels, and process efficiency upgrades could generate new GHG emissions, including emissions stemming from the transportation of clinker material substitutes and alternative fuels as well as embodied emissions from manufacturing and installing new cement plant equipment. Nevertheless, the overall solution effectiveness is not expected to be significantly impacted. In some of the largest cement-producing countries, the emissions from transport of clinker material substitutes has been calculated to be an order of magnitude less than the emissions savings from the use of those substitutes in place of clinker (Shah et al., 2022). 

In terms of environmental impact, some clinker substitutes such as calcined clays and natural pozzolans can increase water use (Juenger et al., 2019; Snellings et al., 2023). Additionally, the use of biomass as an alternative fuel source could lead to trade-offs – such as increased water use and land use, or diminished resource availability – although the risk of this outcome is low since biomass for kiln fuels tends to be agricultural by-products or other waste (Clark et al., 2024; Georgiopoulou & Lyberatos, 2018). 

Reinforcing

Lower-carbon cement will improve the effectiveness and enhance the net climate impact of any solutions that might require new construction. The embodied emissions from the cement and concrete used for new built structures or roads will be reduced.

Technological advancements and increased adoption of efficient cement manufacturing equipment will improve the rate and cost of scaling similar high-efficiency machinery.

Industrial electrification in cement plants will be faster and easier to adopt if the plants’ energy demands are lowered via reduced clinker production and more efficient processes.

Competing

All of these solutions rely on biomass as a raw material or feedstock. For that reason, the use of biomass as an alternative kiln fuel or a source of ash for clinker substitutes will reduce the overall availability of biomass and increase the cost of using it for other applications.

Consensus of effectiveness in reducing cement industry emissions: High

The cement industry produces an estimated 7–8% of global CO₂ emissions (Goldman et al., 2023), so this is an important area to target. There is high scientific consensus that clinker material substitution, alternative fuels, and process efficiency upgrades can be immediately and effectively implemented. Other emissions reduction strategies – including hydrogen kiln fuel, electrification, and carbon capture and storage technologies – have generated mixed scientific opinions on their potential for immediate impact and were not considered in this analysis. 

The U.S. Department of Energy (2022) highlighted cement as one of five high-emitting industries with potential for mitigation. The technologies identified as having the highest level of maturity and market readiness were energy efficiency measures, biomass and natural gas fuels, material efficiency measures, and blended-material cements. 

An extensive review of industrial decarbonization points to four technologies that could be implemented in the near term across global industries: electrification, material efficiency, energy efficiency, and circularity (Rissman et al., 2020). The European Cement Research Academy (2022) classified the three cement industry approaches considered in this solution – clinker material substitution, alternative fuels, and process efficiency upgrades – as meeting the highest technology readiness level.

Goldman et al. (2023) identified clinker material substitution, alternative fuels, and efficiency improvements as deployable today, estimating that these three approaches could abate 30% of U.S. cement industry emissions by 2030. Habert et al. (2020) proposed technologies that could reduce emissions up to 50% in the next few decades, including “cement improvements” of supplementary clinker materials, alternative fuels, and more efficient technologies. The International Energy Agency (IEA, 2018) estimated that clinker material replacement, alternative fuels, and efficiency improvements could provide 37%, 12%, and 3% of cement emissions savings by 2050, respectively.

The results presented in this document summarize findings from two reviews and meta-analyses, eight original studies, nine reports, and several data sets reflecting current evidence from 33 countries, primarily high cement-producing countries in North America, Europe, and Asia. We recognize this limited geographic scope creates bias, and hope this work inspires research and data sharing on this topic in underrepresented regions.

Take Action

Looking to get involved? Below are some key actions for this solution that can get you started, arranged according to different roles you may play in your professional or personal life.

These actions are meant to be starting points for involvement and are not intended to be prescriptive or necessarily suggest they are the most important or impactful actions to take. We encourage you to explore and get creative!

Lawmakers and Policymakers

  • Hold cement manufacturers accountable for safety standards.
  • Regulate clinker material substitution, alternative fuel usage, and process efficiency upgrades.
  • Set standards for low-carbon cement and reporting on embodied carbon for new projects.
  • Provide financial incentives such as grants, subsidies, and/or carbon taxes.
  • Set low-carbon cement standards for public procurement.
  • Implement building codes and standards that allow for the safe, tested use of low-clinker cement while accounting for regional variability in cement compositions.
  • When possible integrate low-carbon cement standards into industry standards such as LEED certification or CALGreen.
  • Increase investment in research and development of clinker material substitutes.
  • Promote a circular economy by creating reverse supply chains to collect industrial and biomass waste to be used as feedstocks for cement kilns and products.
  • Require labels for low-carbon products and materials.
  • Engage impacted communities and incorporate public feedback into policy design.
  • Ensure permit processes for mining or collecting clinker substitutes allow local supply chains to develop.
  • Integrate water management into policy planning when adopting new cement technologies, especially in drought-prone areas.

Further information:

Practitioners

  • Increase the fraction of clinker substitutes in cement, which will reduce production costs.
  • Use alternative fuels as manufacturing energy sources, ideally from renewable sources when possible, which will reduce production costs.
  • Upgrade equipment and production process to be more efficient, which will reduce production costs.
  • Invest in research and development for clinker material substitutes and process improvements.
  • Work to form national and regional industrial strategies for low-carbon cement.
  • Join industry coalitions such as the Global Cement and Concrete Association and/or Concrete Sustainability Council.
  • Engage with local community members and use their feedback to create safer and healthier production facilities.
  • Increase transparency and reporting around the energy usage of manufacturing processes, fuel composition, and the material composition of cement products.
  • Integrate water management safeguards when adopting new cement technologies, especially in drought-prone areas.

Further information:

Business Leaders

  • Source from low-carbon cement producers.
  • Advocate for low-carbon cement during project design and construction.
  • Promote concrete alternatives in high-profile projects.
  • Purchase, promote, and/or invest in local manufacturing and supply chains not only for materials and equipment used to make low-carbon cement, but also for low-carbon cementitious products.
  • Create off-take agreements for emerging cement technologies.
  • Create training and capacity-building programs for industry professionals related to the use and benefits of low-carbon cement and concrete.
  • Launch education and awareness campaigns that share case studies and pilot projects with industry media and other key stakeholders.
  • Leverage carbon markets to help subsidize the cost of low-carbon cement.
  • Work with governments and financial institutions to establish standards and incentives for utilizing low-carbon materials.

Further information:

Nonprofit Leaders

  • Assist with monitoring and reporting related to the energy usage of manufacturing processes, fuel composition, and the material composition of cement products.
  • Help design policies and regulations that support low-carbon cement production.
  • Educate the public about the urgent need for low-carbon cement while showcasing its many benefits.
  • Join or support efforts such as the Concrete Sustainability Council.
  • Encourage policymakers to create ambitious targets and regulations.
  • Encourage cement manufacturers to improve their practices.

Further information:

Investors

  • Invest in low-carbon cement producers, low-carbon cement research and development, and shared recycling infrastructure for cement materials.
  • Invest in supply chains for new clinker substitutes, alternative fuels, and technologies that improve production efficiency.
  • Encourage portfolio companies to produce low-carbon cement or source from low-carbon cement producers, noting that low-carbon retrofits will save money for producers.
  • Seek impact investment opportunities, such as low-interest loans for construction or renovation projects that use low-carbon cement, or favorable loans for entities that set low-carbon cement policies or targets.

Further information:

Philanthropists and International Aid Agencies

  • Set low-carbon cement standards for construction-related grants, loans, and awards.
  • Provide capital for local supply chains and the acquisition or production of clinker material substitutes.
  • Support global, national, and local policies that promote low-carbon cement use.
  • Support accelerators or multilateral initiatives like the Concrete Sustainability Council.
  • Explore opportunities to fund low-carbon cement start-ups.
  • Advance awareness of the public health and climate benefits of low-carbon cement. 

Further information:

Thought Leaders

  • Provide technical assistance (e.g., circular economy design) to producers, government agencies, and other entities working to reduce cement emissions.
  • Help design policies and regulations that support the adoption of low-carbon cement.
  • Educate the public through campaigns emphasizing the urgent need to reduce cement production emissions.
  • Join or support efforts such as the Concrete Sustainability Council.
  • Encourage policymakers to create more ambitious targets and regulations.
  • Pressure the cement industry to improve its production practices.

Further information:

Technologists and Researchers

  • Develop new separation technology for recycling cement material.
  • Assess new clinker substitutes and improve supply chains for known substitutes.
  • Improve the efficiency of processing technology and equipment.
  • Increase the safety of extraction, transport, handling, and processing of clinker material substitutes.
  • Develop on-site testing and reporting methods for tracking the energy use of manufacturing processes, fuel composition, and the material composition of cement products.
  • Examine and refine understandings of the potential revenue and price premiums of low-carbon cement products.

Further information:

Communities, Households, and Individuals

  • Purchase low-carbon cement and concrete products when possible.
  • Document your experiences if harmful cement production practices impact you. Share documentation of harmful cement production practices and/or other key messages with policymakers, the media, and your community.
  • Encourage policymakers to improve regulations related to cement production.
  • Support public education efforts to raise awareness about the urgent need to make cement production practices more environmentally sustainable.
  • Pressure the cement industry to improve its production practices.

Further information:

“Take Action” Sources

References

Afsah, S. (2004). CDM potential in the cement sector: The challenge of demonstrating additionality. Performeks LLC. https://www.performeks.com/media/downloads/CDM-Cement%20Sector_May%202004.pdf 

Cannon, C., Guido, V., & Wright, L. (2021). Concrete solutions guide: Mix it up: Supplementary cementitious materials (SCMs). RMI. https://rmi.org/wp-content/uploads/2021/08/ConcreteGuide2.pdf 

Cao, Z., Masanet, E., Tiwari, A., and Akolawala, S. (2021). Decarbonizing concrete: Deep decarbonization pathways for the cement and concrete cycle in the United States, India, and China. Industrial Sustainability Analysis Laboratory. https://www.climateworks.org/wp-content/uploads/2021/03/Decarbonizing_Concrete.pdf 

Cavalett, O., Watanabe, M. D. B., Voldsund, M., Roussanaly, S., & Cherubini, F. (2024). Paving the way for sustainable decarbonization of the European cement industry. Nature Sustainability, 7, 568–580. https://doi.org/10.1038/s41893-024-01320-y 

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Goldman, S., Majsztrik, P., Sgro Rojas, I., Gavvalapalli, M., Gaikwad, R., Feric, T., Visconti, K., & McMurty, B. (2023). Pathways to commercial liftoff: Low-carbon cement. U.S. Department of Energy. https://liftoff.energy.gov/wp-content/uploads/2023/09/20230918-Pathways-to-Commercial-Liftoff-Cement.pdf 

Gómez, D. R., & Watterson, J. D., et al. (2006). Stationary combustion. In S. Eggelston, L. Buendia, K. Miwa, T. Ngara, & K. Tanabe (Eds.), 2006 IPCC guidelines for national greenhouse gas inventories (Vol. 2). Institute for Global Environmental Strategies (IGES) for the IPCC. https://www.ipcc-nggip.iges.or.jp/public/2006gl/pdf/2_Volume2/V2_2_Ch2_Stationary_Combustion.pdf 

Griffiths, S., Sovacool, B. K., Furszyfer Del Rio, D. D., Foley, A. M., Bazilian, M. D., Kim, J., & Uratani, J. M. (2023). Decarbonizing the cement and concrete industry: A systematic review of socio-technical systems, technological innovations, and policy options. Renewable and Sustainable Energy Reviews, 180, 113291. https://doi.org/10.1016/j.rser.2023.113291 

Habert, G., Miller, S. A., John, V. M., Provis, J. L., Favier, A., Horvath, A., & Scrivener, K. L. (2020). Environmental impacts and decarbonization strategies in the cement and concrete industries. Nature Reviews Earth & Environment, 1, 559–573. https://doi.org/10.1038/s43017-020-0093-3 

Hottle, T., Hawkins, T. R., Chiquelin, C., Lange, B., Young, B., Sun, P., Elgowainy, A., & Wang, M. (2022). Environmental life-cycle assessment of concrete produced in the United States. Journal of Cleaner Production, 363, 131834. https://doi.org/10.1016/j.jclepro.2022.131834 

International Energy Agency. (2018). Technology roadmap: Low-carbon transition in the cement industry. https://www.iea.org/reports/technology-roadmap-low-carbon-transition-in-the-cement-industry 

International Energy Agency. (2023a). CO₂ emitted and captured in the cement sector and clinker-to-cement ratio in the Net Zero Scenario, 2015–2030. https://www.iea.org/data-and-statistics/charts/co2-emitted-and-captured-in-the-cement-sector-and-clinker-to-cement-ratio-in-the-net-zero-scenario-2015-2030 

International Energy Agency. (2023b). Global cement production in the Net Zero Scenario, 2010–2030. https://www.iea.org/data-and-statistics/charts/global-cement-production-in-the-net-zero-scenario-2010-2030-5260 

International Energy Agency. (2023c). Global thermal energy intensity of clinker production by fuel in the Net Zero Scenario, 2010–2030. https://www.iea.org/data-and-statistics/charts/global-thermal-energy-intensity-of-clinker-production-by-fuel-in-the-net-zero-scenario-2010-2030 

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Credits

Lead Fellow

  • Sarah Gleeson, Ph.D.

Contributors

  • James Gerber, Ph.D.

  • Yusuf Jameel, Ph.D.

  • Daniel Jasper

  • Alex Sweeney

Internal Reviewers

  • Aiyana Bodi

  • Hannah Henkin

  • Ted Otte

  • Amanda Smith, Ph.D.

  • Tina Swanson, Ph.D.

Methods and Supporting Data

Methods and Supporting Data

Comments / Questions

  • Greenhouse gas quantity expressed relative to CO₂ with the same warming impact over 100 years, calculated by multiplying emissions by the 100-yr GWP for the emitted gases.

  • Greenhouse gas quantity expressed relative to CO₂ with the same warming impact over 20 years, calculated by multiplying emissions by the 20-yr GWP for the emitted gases.

  • Reducing greenhouse gas concentrations in the atmosphere by preventing or reducing emissions.

  • The process of increasing the acidity of water or soil due to increased levels of certain air pollutants.

  • Benefits of climate solutions that extend beyond their ability to reduce emissions or store carbon (e.g., benefits to public health, water quality, biodiversity, advancing human rights).

  • The extent to which emissions reduction or carbon removal is above and beyond what would have occurred without implementing a particular action or solution.

  • An upper limit on solution adoption based on physical or technical constraints, not including economic or policy barriers. This level is unlikely to be reached and will not be exceeded.

  • The quantity and metric to measure implementation for a particular solution that is used as the reference unit for calculations within that solution.

  • Farming practices that work to create socially and ecologically sustainable food production.

  • Addition of trees and shrubs to crop or animal farming systems.

  • Spread out the cost of an asset over its useful lifetime.

  • A crop that live one year or less from planting to harvest; also called annual.

  • black carbon

  • Made from material of biological origin, such as plants, animals, or other organisms.

  • A renewable energy source generated from organic matter from plants and/or algae.

  • An energy source composed primarily of methane and CO₂ that is produced by microorganisms when organic matter decomposes in the absence of oxygen.

  • Carbon stored in biological matter, including soil, plants, fungi, and plant products (e.g., wood, paper, biofuels). This carbon is sequestered from the atmosphere but can be released through decomposition or burning.

  • Living or dead renewable matter from plants or animals, not including organic material transformed into fossil fuels. Peat, in early decay stages, is partially renewable biomass.

  • A type of carbon sequestration that captures carbon from CO₂ via photosynthesis and stores it in soils, sediments, and biomass, distinct from sequestration through chemical or industrial pathways.

  • A climate pollutant, also called soot, produced from incomplete combustion of organic matter, either naturally (wildfires) or from human activities (biomass or fossil fuel burning).

  • High-latitude (>50°N or >50°S) climate regions characterized by short growing seasons and cold temperatures.

  • The components of a building that physically separate the indoors from the outdoor environment.

  • Businesses involved in the sale and/or distribution of solution-related equipment and technology, and businesses that want to support adoption of the solution.

  • A chemical reaction involving heating a solid to a high temperature: to make cement clinker, limestone is calcined into lime in a process that requires high heat and produces CO₂.

  • A four-wheeled passenger vehicle.

  • Technologies that collect CO₂ before it enters the atmosphere, preventing emissions at their source. Collected CO₂ can be used onsite or in new products, or stored long term to prevent release.

  • A greenhouse gas that is naturally found in the atmosphere. Its atmospheric concentration has been increasing due to human activities, leading to warming and climate impacts.

  • Total GHG emissions resulting from a particular action, material, technology, or sector.

  • Amount of GHG emissions released per activity or unit of production. 

  • A marketplace where carbon credits are purchased and sold. One carbon credit represents activities that avoid, reduce, or remove one metric ton of GHG emissions.

  • A colorless, odorless gas released during the incomplete combustion of fuels containing carbon. Carbon monoxide can harm health and be fatal at high concentrations.

  • Activities or technologies that pull CO₂ out of the atmosphere, including enhancing natural carbon sinks and deploying engineered sinks.

  • Long-term storage of carbon in soils, sediment, biomass, oceans, and geologic formations after removal of CO₂ from the atmosphere or CO₂ capture from industrial and power generation processes.

  • carbon capture and storage

  • carbon capture, utilization, and storage

  • A binding ingredient in concrete responsible for most of concrete’s life-cycle emissions. Cement is made primarily of clinker mixed with other mineral components.

  • methane

  • Gases or particles that have a planet-warming effect when released to the atmosphere. Some climate pollutants also cause other forms of environmental damage.

  • A binding ingredient in cement responsible for most of the life-cycle emissions from cement and concrete production.

  • carbon monoxide

  • Neighbors, volunteer organizations, hobbyists and interest groups, online communities, early adopters, individuals sharing a home, and private citizens seeking to support the solution.

  • A solution that potentially lowers the benefit of another solution through reduced effectiveness, higher costs, reduced or delayed adoption, or diminished global climate impact.

  • A farming system that combines reduced tillage, cover crops, and crop rotations.

  • carbon dioxide

  • A  measure standardizing the warming effects of greenhouse gases relative to CO₂. CO₂-eq is calculated as quantity (metric tons) of a particular gas multiplied by its GWP.

  • carbon dioxide equivalent

  • The process of cutting greenhouse gas emissions (primarily CO₂) from a particular sector or activity.

  • A solution that works slower than gradual solutions and is expected to take longer to reach its full potential.

  • Microbial conversion of nitrate into inert nitrogen gas under low-oxygen conditions, which produces the greenhouse gas nitrous oxide as an intermediate compound.

  • Greenhouse gas emissions produced as a direct result of the use of a technology or practice.

  • Ability of a solution to reduce emissions or remove carbon, expressed in CO₂-eq per installed adoption unit. Effectiveness is quantified per year when the adoption unit is cumulative over time.

  • Greenhouse gas emissions accrued over the lifetime of a material or product, including as it is produced, transported, used, and disposed of.

  • Solutions that work faster than gradual solutions, front-loading their impact in the near term.

  • Methane produced by microbes in the digestive tracts of ruminant livestock, such as cattle, sheep and goats.

  • environmental, social, and governance

  • exchange-traded fund

  • A process triggered by an overabundance of nutrients in water, particularly nitrogen and phosphorus, that stimulates excessive plant and algae growth and can harm aquatic organisms.

  • The scientific literature that supports our assessment of a solution's effectiveness.

  • A group of human-made molecules that contain fluorine atoms. They are potent greenhouse gases with GWPs that can be hundreds to thousands times higher than CO₂.

  • food loss and waste

  • Food discarded during pre-consumer supply chain stages, including production, harvest, and processing.

  • Food discarded at the retail and consumer stages of the supply chain.

  • Combustible materials found in Earth's crust that can be burned for energy, including oil, natural gas, and coal. They are formed from decayed organisms through prehistoric geological processes.

  • greenhouse gas

  • gigajoule or billion joules

  • The glass layers or panes in a window.

  • A measure of how effectively a gas traps heat in the atmosphere relative to CO₂. GWP converts greenhouse gases into CO₂-eq emissions based on their 20- or 100-year impacts.

  • A solution that has a steady impact so that the cumulative effect over time builds as a straight line. Most climate solutions fall into this category.

  • A gas that traps heat in the atmosphere, contributing to climate change.

  • metric gigatons or billion metric tons

  • global warming potential

  • hectare

  • household air pollution

  • Number of years a person is expected to live without disability or other limitations that restrict basic functioning and activity.

  • A unit of land area comprising 10,000 square meters, roughly equal to 2.5 acres.

  • hydrofluorocarbon

  • hydrofluoroolefin

  • Particles and gases released from use of polluting fuels and technologies such as biomass cookstoves that cause poor air quality in and around the home.

  • Organic compounds that contain hydrogen and carbon.

  • Human-made F-gases that contain hydrogen, fluorine, and carbon. They typically have short atmospheric lifetimes and GWPs hundreds or thousands times higher than CO₂. 

  • Human-made F-gases that contain hydrogen, fluorine, and carbon, with at least one double bond. They have low GWPs and can be climate-friendly alternatives to HFC refrigerants.

  • internal combustion engine

  • Greenhouse gas emissions produced as a result of a technology or practice but not directly from its use.

  • Device used to power vehicles by the intake, compression, combustion, and exhaust of fuel that drives moving parts.

  • The annual discount rate that balances net cash flows for a project over time. Also called IRR, internal rate of return is used to estimate profitability of potential investments.

  • Individuals or institutions willing to lend money in search of a return on their investment.

  • internal rate of return

  • A measure of energy

  • International agreement adopted in 2016 to phase down the use of high-GWP HFC F-gases over the time frame 2019–2047.

  • A measure of energy equivalent to the energy delivered by 1,000 watts of power over one hour.

  • kiloton or one thousand metric tons

  • kilowatt-hour

  • A land-holding system, e.g. ownership, leasing, or renting. Secure land tenure means farmers or other land users will maintain access to and use of the land in future years.

  • Gases, mainly methane and CO₂, created by the decomposition of organic matter in the absence of oxygen.

  • leak detection and repair

  • Regular monitoring for fugitive methane leaks throughout oil and gas, coal, and landfill sector infrastructure and the modification or replacement of leaking equipment.

  • Relocation of emissions-causing activities outside of a mitigation project area rather than a true reduction in emissions.

  • The rate at which solution costs decrease as adoption increases, based on production efficiencies, technological improvements, or other factors.

  • Percent decrease in costs per doubling of adoption.

  • landfill gas

  • Greenhouse gas emissions from the sourcing, production, use, and disposal of a technology or practice.

  • low- and middle-income countries

  • liquefied petroleum gas

  • A measure of the amount of light produced by a light source per energy input.

  • square meter kelvins per watt (a measure of thermal resistance, also called R-value)

  • marginal abatement cost curve

  • Livestock grazing practices that strategically manage livestock density, grazing intensity, and timing. Also called improved grazing, these practices have environmental, soil health, and climate benefits, including enhanced soil carbon sequestration.

  • A tool to measure and compare the financial cost and abatement benefit of individual actions based on the initial and operating costs, revenue, and emission reduction potential.

  • A greenhouse gas with a short lifetime and high GWP that can be produced through a variety of mechanisms including the breakdown of organic matter.

  • A measure of mass equivalent to 1,000 kilograms (~2,200 lbs).

  • million hectares

  • Soils mostly composed of inorganic materials formed through the breakdown of rocks. Most soils are mineral soils, and they generally have less than 20% organic matter by weight.

  • A localized electricity system that independently generates and distributes power. Typically serving limited geographic areas, mini-grids can operate in isolation or interconnected with the main grid.

  • Reducing the concentration of greenhouse gases in the atmosphere by cutting emissions or removing CO₂.

  • Percent of trips made by different passenger and freight transportation modes.

  • megaton or million metric tons

  • A commitment from a country to reduce national emissions and/or sequester carbon in alignment with global climate goals under the Paris Agreement, including plans for adapting to climate impacts.

  • A gaseous form of hydrocarbons consisting mainly of methane.

  • Chemicals found in nature that are used for cooling and heating, such as CO₂, ammonia, and some hydrocarbons. They have low GWPs and are ozone friendly, making them climate-friendly refrigerants.

  • Microbial conversion of ammonia or ammonium to nitrite and then to nitrate under aerobic conditions.

  • A group of air pollutant molecules composed of nitrogen and oxygen, including NO and NO₂.

  • A greenhouse gas produced during fossil fuel combustion and agricultural and industrial processes. N₂O is hundreds of times more potent than CO₂ at trapping atmospheric heat, and it depletes stratospheric ozone.

  • Social welfare organizations, civic leagues, social clubs, labor organizations, business associations, and other not-for-profit organizations.

  • A material or energy source that relies on resources that are finite or not naturally replenished at the rate of consumption, including fossil fuels like coal, oil, and natural gas.

  • nitrogen oxides

  • nitrous oxide

  • The process of increasing the acidity of seawater, primarily caused by absorption of CO₂ from the atmosphere.

  • An agreement between a seller who will produce future goods and a purchaser who commits to buying them, often used as project financing for producers prior to manufacturing.

  • Productive use of wet or rewetted peatlands that does not disturb the peat layer, such as for hunting, gathering, and growing wetland-adapted crops for food, fiber, and energy.

  • A measure of transporting one passenger over a distance of one kilometer.

  • The longevity of any greenhouse gas emission reductions or removals. Solution impacts are considered permanent if the risk of reversing the positive climate impacts is low within 100 years.

  • A mixture of hydrocarbons, small amounts of other organic compounds, and trace amounts of metals used to produce products such as fuels or plastics.

  • Private, national, or multilateral organizations dedicated to providing aid through in-kind or financial donations.

  • An atmospheric reaction among sunlight, VOCs, and nitrogen oxide that leads to ground-level ozone formation. Ground-level ozone, a component of smog, harms human health and the environment.

  • passenger kilometer

  • particulate matter

  • Particulate matter 2.5 micrometers or less in diameter that can harm human health when inhaled.

  • Elected officials and their staff, bureaucrats, civil servants, regulators, attorneys, and government affairs professionals.

  • System in a vehicle that generates power and delivers it to the wheels. It typically includes an engine and/or motor, transmission, driveshaft, and differential.

  • People who most directly interface with a solution and/or determine whether the solution is used and/or available. 

  • The process of converting inorganic matter, including carbon dioxide, into organic matter (biomass), primarily by photosynthetic organisms such as plants and algae.

  • Defined by the International Union for the Conservation of Nature as: "A clearly defined geographical space, recognised, dedicated and managed, through legal or other effective means, to achieve the long-term conservation of nature with associated ecosystem services and cultural values". References to PAs here also include other effective area-based conservation measures defined by the IUCN. 

  • Very large or small numbers are formatted in scientific notation. A positive exponent multiplies the number by powers of ten; a negative exponent divides the number by powers of ten.

  • Small-scale family farmers and other food producers, often with limited resources, usually in the tropics. The average size of a smallholder farm is two hectares (about five acres).

  • soil organic carbon

  • Carbon stored in soils, including both organic (from decomposing plants and microbes) and inorganic (from carbonate-containing minerals).

  • Carbon stored in soils in organic forms (from decomposing plants and microbes). Soil organic carbon makes up roughly half of soil organic matter by weight.

  • Biologically derived matter in soils, including living, dead, and decayed plant and microbial tissues. Soil organic matter is roughly half carbon on a dry-weight basis.

  • soil organic matter

  • sulfur oxides

  • sulfur dioxide

  • The rate at which a climate solution physically affects the atmosphere after being deployed. At Project Drawdown, we use three categories: emergency brake (fastest impact), gradual, or delayed (slowest impact).

  • Climate regions between latitudes 23.4° to 35° above and below the equator characterized by warm summers and mild winters.

  • A polluting gas produced primarily from burning fossil fuels and industrial processes that directly harms the environment and human health.

  • A group of gases containing sulfur and oxygen that predominantly come from burning fossil fuels. They contribute to air pollution, acid rain, and respiratory health issues.

  • Processes, people, and resources involved in producing and delivering a product from supplier to end customer, including material acquisition.

  • metric tons

  • Technology developers, including founders, designers, inventors, R&D staff, and creators seeking to overcome technical or practical challenges.

  • Climate regions between 35° to 50° above and below the equator characterized by moderate mean annual temperatures and distinct seasons, with warm summers and cold winters.

  • A measure of how well a material prevents heat flow, often called R-value or RSI-value for insulation. A higher R-value means better thermal performance.

  • Individuals with an established audience for their work, including public figures, experts, journalists, and educators.

  • Low-latitude (23.4°S to 23.4°N) climate regions near the Equator characterized by year-round high temperatures and distinct wet and dry seasons.

  • United Nations

  • Self-propelled machine for transporting passengers or freight on roads.

  • A measure of one vehicle traveling a distance of one kilometer.

  • vehicle kilometer

  • volatile organic compound

  • Gases made of organic, carbon-based molecules that are readily released into the air from other solid or liquid materials. Some VOCs are greenhouse gases or can harm human health.

  • watt

  • A measure of power equal to one joule per second.

  • A subset of forest ecosystems that may have sparser canopy cover,  smaller-stature trees, and/or trees characterized by basal branching rather than a single main stem.

  • year

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