Energies 2021 , 14 , 1161
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Table9. Cont .
Estimated Energy Saving
Estimated Emission Reduction
Typeof Technology
TRL
Description
Ref.
Process
Using hydrogen (purchase (especially green H 2 ) or on-site production by electrolysis) instead of natural gas can significantly reduce CO 2 emissions. By replace fossil fuels with electricity and using an electric boiler instead of a fossil fuel boiler (natural gas boiler) to generate heat (steam) demand, fossil fuel emissions could be eliminated. If the electricity is supplied with renewable sources, net-zero emissions could be reachable. By recovering the waste heat (at low temperature <100 ◦ C) from the process using a heat pump and converting it into medium-temperature heat (max. 160 ◦ C) (Direct information from heat pump manufacturer), energy efficiency would improve, and fossil fuel emissions could be drastically reduced. It may be applied through pre-combustion (associated with black liquor gasification), post-combustion (which is the more straightforward technology), or oxy-combustion technologies DES are produced naturally by plants and can break down wood and selectively extract cellulose fibers required in the papermaking process. This technology could replace the traditional chemical and mechanical pulping techniques by enabling dissolving the wood and extracting lignin, hemicellulose, and cellulose at low temperatures and atmospheric pressure. Deep eutectic solvent could be applied to pulp production from both wood and recovered paper with minimal energy consumption and CO 2 emissions. Pre-cooking of wood in green liquor (20–30% of the green liquor) without the lime reaction, reducing energy consumption, lime kiln load, increasing pulp yield, and bleachability. Partial replacement of the evaporation of black liquor by membrane concentration, reducing the thermal energy needed. This technology aims to reduce the weight of paper without impacting its quality or structure (reducing the amount of material by 30% per square meter). Lighter weight paper needs less energy (steam and electricity) for drying, pumping, and transporting. Wood fibers are partially replaced by fibrous filters (based on calcium and silica), which increase the solid contact of the paper web and then reduces the energy required for the drying section. The concept of this technology is to produce waterless paper using high turbulent steam combined with dry fibers. The technology can be applied to any kind of pulp (chemical, TMP, RCF) and reduces energy consumption and fossil fuel CO 2 emissions. This technology produces paper without water by using two techniques: a dry pulp technique, which consists of a highly viscous solution and contains higher concentrated fibers, and a cure formed technique, which allows the formation of thin sheets. In the press section before the paper drying, water can be removed from the web using a combination of mechanical and air pressure. This technology increases the solids content to 55%, which leads to a reduction in energy consumption in the drying area.
Useof Hydrogen as a fuel
[41,45]
7–8
Direct electric heating
[41,45]
7–8
Steam production
Heat pump recovering wasteheat
[41,45]
6–7
Carbon capture and storage
[10]
6
Deep eutectic solvents (DES)
[13,42]
20%
40% 3
Pulp Production
Utilization of green liquor
25% 7–8
[42,43]
Membrane concentration of black liquor
36% 6–7
[42,43]
Functional surface
8–9
[13,42]
Paper Production
New fibrous fillers
[42,44]
25% 5–6
Flash Condensing
[13,44]
50%
20% 3–5
Forming
Dry pulp for cure-formed paper
55%
25% 3
[13]
Displacement pressing
[18,43]
Press Section
30% 5–6
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