Italy

The world is experiencing the effects of climate change at an increasing rate including rising average global temperature caused primarily by greenhouse gas (GHG) emissions. Energy-intensive industries (EIIs) are major contributors to greenhouse gas emissions. The pulp and paper industry (PPI) is among the top five most energyintensive industries and it accounts for approximately 6 % of global industrial energy use and 2 % of direct industrial CO2 emissions. Therefore it is important to decarbonize this industrial sector to achieve the climate policy goal of achieving net-zero emissions as per the Paris Agreement. This paper presents a comprehensive review of the decarbonization options also known as decarbonization pathways for the pulp and paper industrial sector. These pathways are selected from available literature and they mainly include energy efficiency measures (EEMs) paper recycling switching to carbon-neutral fuels such as biomass and hydrogen electrification of heat supply and carbon capture & storage (CCS) among other emerging technologies. After identifying each decarbonization pathway is discussed in detail with its drivers and barriers to implementation. The Analytical Hierarchy Process AHP a multi-criteria decision-making MCDM technique is carried out to rank the decarbonization pathways on five distinct criteria: cost emission reduction potential technological readiness level (TRL) implementation time and scalability. The ranking is carried out in four distinct criteria weight regimes to present clear choices on different criterion weights. This review paper aims to add to the existing literature to provide clear indications in choosing the pathways toward the decarbonization effort in the pulp & paper industry under various strategic priorities.

Biogas is a crucial renewable energy source for green hydrogen (H2) production reducing greenhouse gas emissions and serving as a carbon-free energy carrier with higher specific energy than traditional fuels. Currently methane reforming dominates H2 production to meet growing global demand with biogas/landfill gas (LFG) reform offering a promising alternative. This study provides a comprehensive simulation-based evaluation of Steam Methane Reforming (SMR) and Dry Methane Reforming (DMR) of biogas/LFG using Aspen Plus. Simulations were conducted under varying operating conditions including steam-to-carbon (S/C) for SMR and steam-to-carbon monoxide (S/CO) ratios for DMR reforming temperatures pressures and LFG compositions to optimize H2 yield and process efficiency. The comparative study showed that SMR attains higher specific H2 yields (0.14–0.19 kgH2/Nm3 ) with specific energy consumption between 0.048 and 0.075 MWh/kg of H2 especially at increased S/C ratios. DMR produces less H2 than SMR (0.104–0.136 kg H2/Nm3 ) and requires higher energy inputs (0.072–0.079 MWh/kg H2) making it less efficient. Both processes require an additional 1.4–2.1 Nm3 of biogas/LFG per Nm3 of feed for energy. These findings provide key insights for improving biogas-based H2 production for sustainable energy with future work focusing on techno–economic and environmental assessments to evaluate its feasibility scalability and industrial application.

Tilos a Greek island in the Mediterranean Sea hosts a pioneering hybrid energy system combining an 800-kW wind turbine and a 160-kWp photovoltaic (PV) field. The predominance of wind power makes the energy production of the island almost constant during the year while the consumption peaks in summer in correspondence with the tourist season. If the island wants to achieve complete selfsufficiency seasonal storage becomes compulsory. This study makes use of measured production data over 1 year to understand the best combination of renewable energy generation and storage to match energy production with consumption. A stochastic optimization based on a differential evolution algorithm is carried out to showcase the configuration that minimizes the levelized cost of required energy (LCORE) in different scenarios. System performance is simulated by progressively increasing the size of the storage devices including a combination of Lithium-ion batteries and power-to-gas-topower (P2G2P) technologies and the PV field. An in-depth market review of current and forecasted prices for RES and ESS components supports the economic analysis including three time horizons (current and projections to 2030 and 2050) to account for the expected drop in component prices. Currently the hybrid storage system combining BESS and P2G2P is more cost-effective (264 €/MWh) than a BESS-only system (320 €/MWh). In the mid-term (2030) the expected price drop in batteries will shift the optimal solution towards this technology but the LCORE reached by the hybrid storage (174 €/MWh) will still be more economical than BESS-only (200 €/MWh). In the long term (2050) the expected price drop in hydrogen technologies will push again the economic convenience of P2G2P and further reduce the LCORE (132.4 €/MWh).

Hydrogen and electric buses are considered effective options for decarbonizing the public transportation sector positioning them as a leader in this transition. This study models the environmental and economic performances of a set of bus powertrain technologies considering a real case-study of suburban public transport in Italy and including fuel cell electric vehicles (FCEV) battery electric vehicles (BEV) biomethane-powered vehicles (CBM) natural gas (CNG) and diesel buses. The environmental performances of FCEV and BEV are significantly influenced by the energy source used for hydrogen production or battery charging. Specifically using the electricity mix for FCEV leads to the highest greenhouse gas emissions and fossil fuel demand. In contrast BEV show better environmental performance than conventional powertrains especially when powered by photovoltaics. When powered by photovoltaics BEV reveal similar results to FCEV in terms of environmental impacts except for resource depletion where both perform poorly. Transitioning from diesel to BEV or FCEV can enhance local air quality regardless of the energy source. The economic analysis indicates that FCEV are the most expensive option followed by BEV both of which are currently costlier than diesel and CNG systems. CBM from waste streams emerges as a cost-effective and environmentally friendly solution. This study suggests prioritizing biomethane derived from biowaste manure and residual biomass (excluding energy crops) as a part of the fuels for public transport decarbonization in the EU to advance EU decarbonization goals despite limitations due to resource availability. Furthermore BEV powered by renewables should be prioritized whenever their range is adequate.

Hydrogen produced through natural gas reforming with carbon capture and storage (blue H2) is expected to supply up to 30 % of global low-carbon hydrogen by 2030. However wide variability in reported findings creates uncertainty about its future role. To address this the present techno-economic-environmental study from a lifecycle perspective evaluates whether blue hydrogen can meet carbon footprint thresholds (3 and 3.4 kg CO2 eq./ kg H2) required to qualify as low-carbon hydrogen. Several configurations of either chemical absorption or lowtemperature CO2 separation techniques integrated with auto-thermal reforming are modeled. Results show that low-temperature separation can achieve comparable or even superior energetic performance to conventional capture methods with cold gas and overall efficiencies reaching up to 80 % and 78 % respectively. The economic analysis estimates the levelized cost of blue hydrogen at 3.5–4 €/kg under 2024 EU average nonhousehold consumer natural gas and electricity prices and 2.4–2.8 €/kg under Italy’s 2024 wholesale prices. From an environmental standpoint life-cycle assessment indicates an average carbon footprint of 2.5 kg CO2 eq./ kg H2 assuming photovoltaic electricity for auxiliary power and excluding more carbon-intensive natural gas supply chains. The findings highlight that partial electrification of the CO2 separation unit use of renewable electricity and maximizing capture rates are key factors essential for producing compliant blue H2. Furthermore adopting ultra-low-emission natural gas supply chains could reduce blue H2′s carbon footprint to the level of green H2 suggesting that the introduction of certificate-of-origin schemes for natural gas can guarantee blue H2 with minimal emissions.

Hydrogen-fueled Internal Combustion Engines (H2-ICEs) are typically operated with lean mixtures to minimize NOx emissions and reduce the risk of abnormal combustion events. Due to hydrogen’s low Lewis number premixed hydrogen-air flames in lean conditions exhibit strong thermodiffusive instabilities which make the numerical simulation of the combustion process particularly challenging. Indeed the intensity of these instabilities is significantly influenced by thermodynamic parameters – such as mixture temperature pressure and dilution rate – resulting in substantial variations in combustion behaviour across different operating conditions. Therefore they have to be properly considered not only to ensure model robustness but also to improve model accuracy over a wider range of operations. In this study the combustion process in a Direct Injection H2-ICE was analyzed using 3D-CFD simulations relying on a flamelet-based combustion model. Two sets of lookup flame speed maps were defined: laminar flame speed (SL) maps derived from standard 1D-CFD simulations in homogeneous reactor and freely propagating flame speed (SM) maps which account for the effects of thermodiffusive instabilities. The model that uses SL maps required the recalibration of some combustion model parameters when changing the dilution rate to ensure consistency with experimental data. Instead the model relying on SM maps featured a noticeable accuracy across different air-to-fuel ratios without the need for recalibration any combustion model parameter highlighting the key role of thermodiffusive flame instabilities on the combustion process. Based on these findings the impact of such instabilities was evaluated throughout the entire combustion process from both global and local perspectives. The relevance of thermodiffusive instabilities was observed to increase with the air-to-fuel ratio thereby enhancing combustion speed in leaner mixtures. Additionally the implementation of thermodiffusive instabilities was found to affect also preferred direction of flame propagation as stronger instabilities were identified in the leanest and low-temperature portions of the flame front. Novelty and significance This study addresses a critical knowledge gap regarding the role of thermodiffusive flame instabilities in accurately replicating the combustion process of a direct-injection internal combustion engine within a RANS simulation framework. Indeed while these instabilities have been shown to significantly enhance the mixture consumption rate in quiescent environments at low to moderate pressures and temperatures particularly in lean mixtures their impact on the burn rate under engine-like conditions has not yet been systematically investigated to the best of the authors’ knowledge. This work provides a comprehensive analysis of the significance of these instabilities in the combustion process of a direct-injection hydrogen internal combustion engine. The analysis is conducted from both a global perspective assessing their overall influence on the combustion process and a local perspective examining how they alter flame front characteristics when incorporated into the model.

The governance of the EU energy sector has gradually evolved over time to reflect and support the closer integration of the Internal Electricity Market. As the EU energy sector faces new challenges both at the local and cross-border levels its governance might once again need to be reviewed to ensure that it remains fit for the future. This Policy Brief highlights three opportunities for streamlining the governance of the electricity (and gas) sector(s) at the cross-border level related to: (i) the ‘all TSOs’ or ‘all relevant TSOs’ processes; (ii) the regulatory oversight of EU-wide entities; and (iii) the operation of the electricity market coupling. Other areas for improvement in the current governance framework may also emerge and one suggestion relates to the dual role of the ENTSOs both as (i) entities responsible for a number of essential tasks for the energy sector and (ii) associations with TSOs as their members.

The paper investigates the potential of co-electrolysis as a viable pathway for hydrogen production and industrial decarbonization expanding on previous studies on water electrolysis. The analysis adopts a general and critical perspective aiming to assess the realistic scope of this technology with regard to current energy and environmental needs. Although co-electrolysis theoretically offers improved efficiency by simultaneously converting H2O and CO2 into syngas the practical advantages are difficult to consolidate. The study highlights that the energetic margins of the process remain relatively narrow and that several key aspects including system irreversibility and the limited availability of CO2 in many contexts significantly constrain its applicability. Despite the growing interest and promising technological developments co-electrolysis still faces substantial challenges before it can be implemented on a larger scale. The findings suggest that its success will depend on targeted integration strategies advanced thermal management and favorable boundary conditions rather than on the intrinsic efficiency of the process alone. However there are specific sectors where assessing the implementation potential of co-electrolysis could be of interest a perspective this paper aims to explore.

Pressure collapse in sloshing cryogenic liquid hydrogen tanks is a challenge for existing models which often diverge from experimental data. This paper presents a novel lumped-parameter model that overcomes these limitations. Based on a control volume analysis our approach simplifies the complex non-equilibrium physics into a single dimensionless ordinary differential equation governing the liquid’s temperature. We demonstrate this evolution is controlled by one key parameter: the interfacial Nusselt number (). A method for estimating directly from pressure data is also provided. Validated against literature data the model predicts final tank temperatures with deviation of 0.88K (<5% relative error) from measurements thereby explaining the associated pressure collapse. Furthermore our analysis reveals that the Nusselt number varies significantly during a single sloshing event—with calculated values ranging from a peak of 5.81 × 105 down to 7.58 × 103—reflecting the transient nature of the phenomenon.

Massive theoretical and applied research is underway worldwide to assess the viability of transporting natural gas-hydrogen blends in pipelines. For the first time this work derives simplified but closed-form equations that describe how changes in gas properties due to hydrogen blending at different volumes map to specific changes in pressure drop compressor power and linepack. These first-of-their-kind equations which are extensively validated against transient gas flow models enabled three unprecedented and unique findings. The first finding which quantifies how a change in demand maps to a change in delay and swing on the supply side reveals that pressure swings increase monotonically with an increase in hydrogen blending volume translating into an increase in pipeline fatigue and risk of failure. The second finding crucially shows that pressure drop does not monotonically increase with an increase in hydrogen blending volume; in fact it is highest at around 85 % hydrogen volume not at 100 %. The third finding shows that the decrease in linepack as a result of an increase in hydrogen volume is not only related to the gross calorific value of the gas mixture but also to the pressure-tocompressibility factor ratio suggesting that smaller parallel pipelines can offset this linepack reduction compared to a single larger pipeline.