Publications

The transport of natural gas blended with hydrogen is a key strategy for the low-carbon energy transition. However the influence mechanism of its thermo-physical property variations on centrifugal compressor performance remains insufficiently understood. This study systematically investigates the effects of the hydrogen blending ratio (HBR 0–30%) inlet temperature and rotational speed on key compressor parameters (pressure ratio polytropic efficiency and outlet temperature) through numerical simulations. In order to evaluate the influence of hydrogen blending on the performance and stability of centrifugal compressors a three-dimensional model of the compressor was established and the simulation conducted was verified with the experimental data. Results indicate that under constant inlet conditions both the pressure ratio and outlet temperature decrease with increasing HBR while polytropic efficiency remains relatively stable. Hydrogen blending significantly expands the surge margin shifting both surge and choke lines downward and consequently reducing the stable operating range by 27.11% when hydrogen content increases from 0% to 30%. This research provides theoretical foundations and practical guidance for optimizing hydrogen-blended natural gas centrifugal compressor design and operational control.

In light of increased international efforts to combat climate change sustainable infrastructure is shifting toward green hydrogen produced through renewable-powered electrolysis. Still it is challenging to forecast the production of green hydrogen because environmental and system factors are variable both in time and space. We introduce a new system that utilizes a Spatio-Temporal Graph Convolutional Network (STGCN) and a novel algorithm the Ninja Optimization Algorithm (NiOA) to address this issue. Using the framework binary NiOA performs feature selection while continuous NiOA optimizes both the model architecture and the number of variables in the data simultaneously. It is clear from the research that forecasting results have shown significant improvement. The STGCN model achieved an R2 of 0.8769 and an MSE of 0.00375 whereas the STGCN with NiOA reached an R2 of 0.9815 and an MSE of only 7.48 × 10−8. Due to these improvements adaptive metaheuristics show even greater promise in delivering more accurate forecasting and reduced computational requirements for addressing critical environmental issues. The suggested strategy can be followed repeatedly providing a solid framework for the effective modeling of renewable energy systems and making green hydrogen projects more dependable.

As hydrogen gains prominence in energy systems its adoption as an energy source for fuel cell electric vehicles (FCEVs) necessitates the establishment of hydrogen refueling stations (HRS). These stations contain critical compo-nents including nozzles storage tanks heat exchangers and compressors which must be certified by regulatory agen-cies to ensure safety and public trust. Current certification processes are fragmented and manually intensive creating inefficiencies and limiting transparency across the infrastructure lifecycle. In this paper we propose a blockchain-based solution that creates a secure and auditable network for certifying key HRS components. The system integrates an EVM-compatible blockchain decentralized storage and a modular suite of smart contracts (SCs) that formalize registration bidding accreditation certification and governance. Each contract encodes a distinct actor-driven work-flow enabling traceable and role-specific operations. A Decentralized Application (DApp) interface supports real-time and role-based interaction across the ecosystem. We present and evaluate the SCs and their underlying algorithms us-ing gas usage analysis load testing and security auditing. Load testing across the certification lifecycle shows stable transaction throughput and predictable cost profiles under increasing actor activity. A static security analysis con-firms resilience against common vulnerabilities. Our cost analysis indicates that while the framework is technically deployable on public blockchains the execution costs of certain functions make it more cost-effective for private blockchains or Layer 2 networks. We also compare our framework with existing systems to highlight its novelty and technical advantages. Our SCs DApp interface and load testing scripts are publicly available on GitHub.

Given the Kenyan challenges in energy availability accessibility and affordability exploring green hydrogen as a sustainable energy solution is supreme. This study aimed to assess the potential of green hydrogen production a transformative clean energy technology and its implications for Kenya's future energy. The specific objectives were to identify the drivers of change that could accelerate green hydrogen adoption and policy recommendations. The study employed a scenario planning approach focusing on four key steps: defining the scenario and time horizon identifying drivers of change and developing and applying scenarios. The diffusion of innovation theory guided the study. Twelve key critical drivers of change were identified with societal and industry acceptance of green hydrogen and compatibility with existing energy infrastructure being the strongest drivers of change from cross-impact analysis results. The study outlined four plausible future scenarios for adoption: Successful Production (best scenario) Low Production Chaotic Transition and Rejection of Green Hydrogen Production (worst scenario). Major opportunities include advancements in hydrogen production export potential and job creation. Cost competitiveness analysis is essential comparing Kenya's hydrogen with traditional fuels and African peers. Economic models suggest that Kenya's renewable energy can lower costs enhancing its position in clean energy innovation. However critical challenges involve regulatory uncertainty ethical concerns public misconceptions about green hydrogen safety and financial barriers due to high initial investment costs. The study recommended that the Kenyan government invest in renewable energy infrastructure formulate a comprehensive national hydrogen policy and establish an enabling environment to attract private investment. In conclusion green hydrogen production stands as a strategic pillar for Kenya’s sustainable energy transition and further research should focus on strengthening regulatory frameworks and enhancing public engagement to unlock its full potential.

Hydrogen will play a critical role in decarbonizing diverse economic sectors. However given limited sustainable resources and the energy-intensive nature of its production prioritizing its applications will be essential. Here we analyse approximately 2000 (low-carbon) hydrogen projects worldwide encompassing operational and planned initiatives until 2043 quantifying their greenhouse gas (GHG) emissions and mitigation potential from a life cycle perspective. Our results demonstrate the variability in GHG emissions of hydrogen applications depending on the geographical location and hydrogen source used. The most climate-effective hydrogen applications include steel-making biofuels and ammonia while hydrogen use for road transport power generation and domestic heating should be discouraged as more favourable alternatives exist. Planned low-carbon hydrogen projects could generate 110 MtH2 yr−1 emit approximately 0.4 GtCO2e yr−1 and potentially reduce net life cycle GHG emissions by 0.2–1.1 GtCO2e yr−1 by 2043 depending on the substituted product or service. Addressing the current hydrogen implementation gap and prioritizing climate-effective applications are crucial for meeting decarbonization goals.

Hydrogen-based fuels are potential candidates to help international shipping achieve net-zero greenhouse gas (GHG) emissions by around 2050. This paper quantifies the environmental impacts of liquid hydrogen liquid ammonia and methanol used in a Post-Panamax container ship from 2020 to 2050. It considers cargo capacity changes electricity decarbonization and hydrogen production transitions under two International Energy Agency scenarios: the Stated Policies Scenario (STEPS) and the Net Zero Emissions by 2050 Scenario (NZE). Results show that compared to the existing HFO ship hydrogen-based propulsion systems can decrease cargo weight capacity by 0.3 % to 25 %. In the NZE scenario hydrogen-based fuels can reduce GHG emissions per tonne-nautical mile by 48 %–65 % compared to heavy fuel oil by 2050. Even with fully renewable hydrogenbased fuels 18 %–31 % of GHG emissions would still remain. Using hydrogen-based fuels in internal combustion engines requires attention to minimize environmental trade-offs.

Global renewable hydrogen trade is expected to play a key role in decarbonizing future energy systems. Yet hydrogen exporters may deviate from perfectly competitive behaviour to influence prices similarly to the existing fossil fuel market with important implications for consumer welfare and the pace of the energy transition. This study develops a global renewable hydrogen trade model that captures potential strategic interactions among exporters using a Stackelberg game-theoretic framework. The model is formulated as an Equilibrium Problem with Equilibrium Constraints (EPEC) and solved under three alternative equilibria: a profitmaximizing Nash equilibrium a cost-minimizing Nash equilibrium and a welfare-maximizing benchmark representing perfect competition. Results indicate that producers may strategically reduce their export quantities by up to 40 % relative to perfect competition to maximize profits. Such behaviour raises prices to a minimum of 4.5 USD/kg in 2050 across major import markets thereby significantly eroding consumer surplus. Strategic behaviour of dominant exporters also shifts trade flows reshaping the global allocation of hydrogen supply. Sensitivity analysis further reveals that financing costs play a key role in shaping strategic producers’ behaviour with lower financing costs helping to reduce prices and stimulate demand. These findings highlight the implications of imperfect competition in global hydrogen trade and suggest that policy measures may be needed to mitigate potential negative consequences.

This study investigates the cost-optimal capacity and operation of water electrolyzers in global net-zero CO2 energy systems. The production costs of hydrogen are largely determined by the electrolyzer capacity factor (i.e. full-load hours); therefore a global energy system model with an hourly temporal resolution was employed to consider the intermittency of variable renewable energy (VRE) and the dynamics of power system operations. Proton exchange membrane electrolysis is assumed in this study. The optimization results suggest three main findings. First water electrolysis is estimated to be a cost-effective option for achieving net-zero CO2 emissions. Under default technology assumptions the global installed capacity is projected to reach 2719 GW by 2050 with the majority of hydrogen consumed in the industry sector. Scaling up the supply chain is essential to realize this pathway. Second hydrogen and hydrogen-based fuels are economically competitive with negative emission technologies (NETs). A modest deployment of CO2 storage and NETs provides favorable conditions for water electrolysis deployment—and vice versa. Third flexible operation is critical to the widespread deployment of water electrolysis. In the default case the global weighted average capacity factor of electrolyzers is estimated at 37 % in 2050 to follow VRE output fluctuations. The results also indicate that limited operational flexibility may significantly hinder the cost-competitiveness of electrolyzer deployment.

In 2023 global carbon dioxide emissions reached 40 billion tonnes 60 % more than in 1990 intensifying climate concerns. This study explores hydrogen-natural gas blending as a transitional strategy for decarbonization across several regions and energy sectors – residential commercial industrial and agricultural. A multi-regional analysis framework evaluates integration of 20 % by volume low-carbon hydrogen blending into natural gas systems by identifying hydrogen producers importers and exporters based on production and import costs. Applied to Canada 528 scenarios (2026–2050) assess inter-regional hydrogen trade within Canadian provinces. The lowest-cost scenario involves Alberta exporting hydrogen produced through autothermal reforming with 91 % carbon capture and storage and British Columbia producing its own. The grid electrolysis scenario achieves the highest GHG reductions with a 4.5 % GHG mitigation in Canada with full energy system representation. These findings provide insights for policymakers and stakeholders in advancing hydrogen infrastructure and decarbonization strategies.

Fluidized bed systems play a crucial role in industrial processes such as combustion and gasification. In the Iron Power Cycle fluidized bed systems are essential for enabling the reduction of combusted iron back to iron making them a critical component in the regeneration step of the cycle. This study investigates the impact of operating gas velocity on conversion by performing reduction experiments at three distinct fluidization numbers (us/umf): 16 (bubbling regime) 55 (transition region) and 100 (fully turbulent regime). Experiments were conducted to determine the appropriate velocities for each regime ensuring optimal fluidization conditions across reduction temperatures ranging from 500 to 700 ⚬C. The results reveal that conversion rates increase significantly with gas velocities. At 500 ⚬C operating at approximately six times higher velocity leads to a sixfold improvement in conversion when using iron-oxide particles with a Sauter mean diameter of 61 µm. However while enhanced velocities improve reaction efficiency challenges remain at elevated temperatures (T ≥ 500 ⚬C) where iron undergoes defluidization when exposed to hydrogen. Once defluidization occurs refluidization proves impossible with either hydrogen or nitrogen raising concerns about process stability. These insights highlight the potential for optimizing fluidized bed reduction through velocity control while also underscoring the need for additional measures to mitigate unstable fluidization during high-temperature iron oxide reduction.