Decarbonization of the Cement Industry
1. Introduction
Clinker Substituion
4. Results: New consumption and emission profile
Cement is the second most consumed product globally, after water, and it the
primary material for the construction and infrastructure industry. It is composed
by sand, limestone, bauxite, iron ore and may comprise chalk, clay and other raw
materials. Cement alone is responsible for about 3-4% of European greenhouse
gas emissions.
Over the past years, CO2 emissions from cement industry increased drastically
driven by the increase in global population and the subsequent demand for infrastructure development (Emele, L. et.al., 2022).
Most of the CO2 (about two-thirds) emissions of cement production are mostly unavoidable and come from
the clinker production. Therefore, the CO2 emissions of cement production is directly proportional to its clinker
factor (the amount of clinker in the final cement product) (Czigler et al., 2020). The average European cement
is current composed of 75% of Portland Cement Clinker (clinker factor of 0.75) (Shah et al., 2022).
The clinker factor of the Cement plant under evaluation here is currently at 0.95, which classifies the cement
produced by this specific plant as CEM I under the European standard EN197-1 (Shah et al., 2022). Here a reduction from 0,95 clinker factor to 0,70 with substitution done by fly ash addition, leading to reclassification
of the type of cement produced to CEM II/ B-V (25% fly ash/70% Portland Cement Clinker).
By implementing the proposed technologies and strategies here mentioned, the total CO2 emissions reduction was of ca. 55% at a total investment costs of 4,632,500
€. The graphs below represents the new energy consumption profile, remaining
CO2 emissions and investment costs of each strategy applied.
2. Case description
The case study here presented focus on
the decarbonization strategy for a Cement
manufacturing plant with a production capacity of 600kt/year. The plant is localized
Berlin, Germany and produces Portland
clinker cement (Cement type according to
the European Classification: CEM I = 0,95
clinker factor). The strategy here proposed
aim to achieve 50% CO2 emissions reduction from its current state (baseline data)
and estimate the respective investment costs. Potential options for the 90% decarbonization strategy are briefly discussed.
Source: Irish Cement (2021)
Renewable Power Purchase Agreements
Renewable Power Purchase Agreements (PPAs) are long-term contracts for electricity supply between a business and a renewable energy generator (RWE, 2023). Such contracts define volume and pricing mechanisms
for renewable electricity delivery in advance (i.e., delivery scheduled to a specific time in the future) (Deloitte,
2022).
For the current strategy, a physical PPA was selected, with a 10-year contract with volume define by facility
profile at a fixed price of 60€/MWh. A Physical PPA involves the actual delivery of the electricity from the generator to the business consumer so they can fulfill their own consumption needs with renewable energy. For
this, the supplier also transfers Renewable certificates/Guarantees of Origin so the Business consumer can
make legal claims of renewable electricity source (Deloitte, 2022).
5. Potential technologies for 90% decarbonization
strategy
Solar Calcination
But by using solar energy in the calcination process, it is possible to significantly reduce the CO2 emissions by reducing fuel consumption and decreasing operational
costs. The hybrid operation can be used so that the plant can work both with solar
power and conventional coal-fired power.
Baseline data was used to calculate the total energy consumption, CO2 emissions, and operational costs of the cement plant at its current states (i.e., before
decarbonization strategy implementation). The following values were found:
Source: Moumin et. al. (2020)
Source: Delloite (2022)
Vertical Roller Mill
Within the cement industry, ball mill grinders are largely being replaced by Vertical Roller Mill (VRM) as they
provide an energy efficiency gain of 50-60% and about 6 to 8% savings in cost (€kWh/t). In a Vertical Roller
Mill, particle size reduction occurs due to the pressure and shear forces applied by the grinding rollers. Additionally, the recirculation factor in a ball mill typically ranges from 2 to 3, whereas in a VRM, it increases to a range
of 6 to 20, depending on factors such as pressure, height, grinding tool configuration, material grindability, and
desired product fineness.
3. Path to 50% reduction in CO2 emissions
Alternative Fuel: Biomass
Throughout research were performed on the techno-economic potential of multiple decarbonization strategies and technologies that could guarantee the target
of 50% emissions decrease CO2 emissions. The following technologies were selected for implementation:
Biomass is one of the possible alternative fuels that can be used for combustion in the clinker. Biomass is a
carbon-neutral alternative to fossil fuel such as pet coke. Beyond providing a possibility to reduce emissions
from burning fossil fuel, another reason for the attractiveness of biomass as alternative fuels are the potential
savings in costs, especially in waste management.
The two most used alternative fuels in the German and Austrian Cement Industry is Solid Recovered Fuel or
Recovered Fuel, which has been defined as “fuels prepared from nonhazardous waste to be utilized for energy
recovery in waste incineration or co-incineration plants regulated under community environmental legislation.
In order to get 100 % of the energy required from SRF, a retrofit to the combustion system would be necessary.
Carbon capture, use, and storage
This method isolates and collects CO2 from industrial emissions and either recycles it for further industrial use or safely stores it underground. Once captured, a
wide variety of potential uses for CO2 could be possible. Though carbon-capture
technologies do exist commercially, they are utilized in very few plants (e.g., natural-gas plants). Therefore, the progress of extensive decarbonization will not only
depend on the economic viability of storing and sequestering the carbon but also
on the availability of CO2 marketplaces, through which the captured CO2 can be
sold (Czigler et al., 2020).
Carbon-cured concrete
This technology injects CO2 released during the cement production to accelerate
the curing process of the concrete, locking in this CO2 in the final product. Currently this technology sequester up to 5% of the CO2 emissions, with the potential
to reach 30% sequestration rate by 2050 (Czigler et al., 2020).
Presentend by
- Leticia Marques Ramos
- Ian Gitau Mwathi
- Ashisk Kashik
- Gowtham Ramesh