Russell McKenna

Last Name

McKenna

First Name

Russell

ORCID

0000-0001-6758-482X

Organisational unit

09752 - McKenna, Russell / McKenna, Russell

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Publications 1 - 10 of 134

A statistical approach to identify asynchronous extreme events for multi-regional energy system models
Khuong, Phuong Minh; Yilmaz, Hasan Ü.; McKenna, Russell; et al. (2021)
International Journal of Energy Sector Management
Purpose With the growing deployment of variable renewable energy sources, such as wind and PV and the increasing interconnection of the power grid, multi-regional energy system models (ESMs) are increasingly challenged by the growth of model complexity. Therefore, the need for developing ESMs, which are realistic but also solvable with acceptable computational resources without losing output accuracy, arises. The purpose of this study is to propose a statistical approach to investigate asynchronous extreme events for different regions and then assess their ability to keep the output accuracy at the level of the full-resolution case. Design/methodology/approach To extract the extreme events from the residual demands, the paper focuses on analyzing the tail of the residual demand distributions by using statistical approaches. The extreme events then are implemented in an ESM to assess the effect of them in protecting the accuracy of the output compared with the full-resolution output. Findings The results show that extreme-high and fluctuation events are the most important events to be included in data input to maintain the flexibility output of the model when reducing the resolution. By including these events into the reduced data input, the output's accuracy reaches the level of 99.1% compared to full resolution case, while reducing the execution time by 20 times. Originality/value Moreover, including extreme-fluctuation along with extreme-high in the reduced data input helps the ESM to avoid misleading investment in conventional and low-efficient generators.
Global greenhouse gas emissions mitigation potential of existing and planned hydrogen projects
Terlouw, Tom Mike; Moretti, Christian; Harpprecht, Carina; et al. (2025)
Nature Energy
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 2,000 (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.
Letter to the Editor regarding “Methodological framework for life cycle assessment of sustainable aviation (SA) systems”
Weinold, Michael; McKenna, Russell (2025)
Science of The Total Environment
Quantifying the trade-offs between renewable energy visibility and system costs
Tsani, Tsamara; Pelser, Tristan; Ioannidis, Romanos; et al. (2025)
Nature Communications
Visual landscape impacts on scenic and populated places are among significant factors affecting local acceptance of large-scale renewable energy projects. Through the combination of large-scale reverse viewshed and techno-economic energy system analyses, we assess their potential impacts for nationwide energy systems. In our case study of Germany, moderate consideration of visual impact by placing renewables out of sight of the most scenic and densely populated areas does not have a significant impact on future energy system costs and design. In contrast, in scenarios assuming high sensitivity to visual impacts, annual energy system costs would increase by up to 38% in 2045. The energy system’s resilience would also be compromised due to the increasing reliance on green hydrogen imports and the uncertain mass adoption of rooftop photovoltaics. Our analytical framework facilitates careful planning that considers the visual impact of renewable energy infrastructure, thus enabling socially acceptable deployment while understanding the implications for system costs and transformation pathways.
A critical reflection on modelling approaches for heat pumps and building envelope retrofits in local energy system optimisations
Hermann, Julian; Kachirayil, Febin; Lohrmann, Alena; et al. (2025)
Applied Energy
Integrating heat pumps and adopting building envelope retrofit (BER) measures is vital for decarbonising the built environment. This paper systematically reviews modelling approaches for these technologies within 84 local energy system optimisation studies. Our findings show that most studies simplify heat pump operation using a constant coefficient of performance (COP), perfect modulation, or a fixed heating capacity. While existing methods account for temperature-dependent COPs, only a few studies include more advanced approaches considering additional impacts. Two main approaches for modelling BER measures are identified: pre-defined retrofit sets with exogenous heat demand or an integrated retrofit selection with endogenous heat demand. While the pre-defined approach offers lower computational effort, it limits the BER solution space. The integrated approach achieves the opposite: a wider solution space but higher complexity. Moreover, only two studies consider the impact of BER measures on the heat supply temperature, an essential link between retrofit measures and heat pump efficiency. Based on our qualitative review, we derive recommendations for energy system modellers. For modelling heat pumps, we recommend using a temperature-dependent COP and heating capacity, as well as a lower modulation limit. Regarding BER measures, the integrated approach should be used for smaller scales (single buildings) while the pre-defined sets are suitable for larger scales. Finally, we propose a research agenda to address limitations and gaps in the current modelling approaches, such as addressing the performance gap between existing COP estimations and heat pump field performance and including a more detailed method for the heat supply temperature.
Designing multi-energy systems in Mediterranean regions towards energy autonomy
Terlouw, Tom Mike; Savvakis, Nikolaos; Bauer, Christian; et al. (2025)
Applied Energy
Decentralized multi-energy systems (MESs) are a key element of a future low-carbon energy supply. Here, we address the crucial role of grid-connected and off-grid MESs in achieving a low-carbon future, particularly relevant for regions like the Mediterranean with high renewable energy potential and carbon-intensive grid networks, using a mixed integer linear program for optimal economic and environmental MES design considering location-specific regulations. The results reveal that substantial cost (up to 30%, potentially saving 1.6 million) and greenhouse gas (GHG) emission reductions can be reached in Mediterranean regions with sufficient solar and wind energy resources currently relying on fossil fuel-based generators. However, our case study shows that the actual cost and emission reductions are most likely limited due to location-specific regulations (limiting cost savings to 0.8 million), especially those that constrain solar photovoltaic and onshore wind. Off-grid energy systems might be suitable decarbonization options in Mediterranean regions, to avoid absorbing current GHG-intensive power from the local power grid, under marginal cost increase (15%) compared to grid-connected cost optimization. However, off-grid MESs require substantial upfront investments and exhibit some environmental trade-offs, especially on material utilization, which could be overcome by balanced autonomy. Overall, truly sustainable and secure decentralized energy systems can only be reached by considering life cycle environmental impacts, social acceptance, and regulations during the design phase.
Realistic roles for hydrogen in the future energy transition
Johnson, Nathan; Liebreich, Michael; Kammen, Daniel M.; et al. (2025)
Nature Reviews Clean Technology
Hydrogen has been promoted as a revolutionary fuel for 50 years, yet usage is confined to oil refining and fertilizer production. For hydrogen to advance global decarbonization, many barriers must be overcome. In this Perspective, we examine the challenges hydrogen faces from production to usage, assessing its environmental and economic credentials, controversies and uncertainties. We provide the evidence base for companies and governments to assess clean hydrogen’s current and potential future competitiveness. Fuel cell cars and space heating are among the least promising applications owing to rapid advances in direct electric alternatives. Hydrogen holds potential in industry, long-duration energy storage and long-haul transport, but its competitiveness depends on large-scale deployment yielding substantial cost reductions. Current production cost estimates range by a factor of five and suggest that targets for 2030 will be difficult to achieve, especially once costs for transport and storage are included. The climate impacts of hydrogen production are also uncertain, with production from electrolysis or methane gas with carbon capture potentially increasing system-wide or upstream emissions, alongside water scarcity and persistent organic pollution. Future research must resolve these uncertainties, with strategic focus on deploying hydrogen in priority areas where it is most competitive.
System impacts of wind energy developments: Key research challenges and opportunities
McKenna, Russell; Lilliestam, Johan; Heinrichs, Heidi U.; et al. (2025)
Joule
Wind power accounted for 8% of global electricity generation in 2023 and is one of the cheapest forms of low- carbon electricity. Although fully commercial, many challenges remain in achieving the required scale-up, relating to integrating wind farms into wider technical, economic, social, and natural systems. We review the main challenges, outline existing solutions, and propose future research needed to overcome existing problems. Although the techno-economic challenges of grid and market integration are seen as significant obstacles to scaling up wind power, the field is replete with solutions. In many countries, planning and permitting are immediate barriers to wind-power deployment; although solutions are emerging in the EU and several countries, the effectiveness and long-term acceptance of fast-track permissions and go-to areas remains to be seen. Environmental impacts on wildlife and recycling challenges are rising issues for which tested and scalable solutions are often still lacking, pointing to large remaining research requirements.
Transforming decentralized energy systems: Flexible EV charging and its impact across urbanization degrees
Brodnicke, Linda; Kachirayil, Febin; Gabrielli, Paolo; et al. (2025)
Applied Energy
Electric vehicles (EVs) are critical to decarbonize personal transportation, yet they significantly increase electricity demands, challenging local energy systems. This study investigates the impact of various EV charging strategies on the optimal energy system design and operation across different degrees of urbanization. Using empirical data, electric vehicle driving behavior is captured within a municipal energy system optimization framework that models the transition to a net zero emissions energy system by 2050. Inflexible passive charging is evaluated against time-shifted smart charging and bi-directional vehicle-to-grid (V2G) across rural, suburban, and urban case studies in Northern Germany. This study identifies two main benefits of flexible EV charging. First, stationary storage requirements are significantly reduced compared to passive charging. The rural and suburban case studies, dominated by wind power, need less than 1 kWh of stationary storage per dwelling with passive charging in 2050 and eliminate storage needs with any kind of flexible EV charging. In contrast, the urban case study with limited wind potential and significant solar resources requires 11.5 kWh of stationary storage with passive charging, reduced by 20% with smart charging and by 35% with V2G. Second, while wind-dominated cases achieve higher self-consumption due to better alignment of EV charging with renewable generation, the urban case study benefits from earlier solar PV deployment with V2G, boosting self-sufficiency. These findings challenge the need for stationary storage in the presence of widespread flexible EV charging. Notably, V2G provides no significant advantage over smart charging in wind-dominated areas, emphasizing the need for context-specific EV integration strategies.
Comparing empirical and model-based approaches for calculating dynamic grid emission factors: An application to CO2-minimizing storage dispatch in Germany
Braeuer, Fritz; Finck, Rafael; McKenna, Russell (2020)
Journal of Cleaner Production
As one possibility to increase flexibility, battery storage systems (BSS) will play a key role in the decarbonization of the energy system. The emissions-intensity of grid electricity becomes more important as these BSSs are more widely employed. In this paper, we introduce a novel data basis for the determination of the energy systems CO2 emissions, which is a match between the ENTSO-E database and the EUTL databases. We further postulate four different dynamic emission factors (EF) to determine the hourly CO2 emissions caused through a change in electricity demand: the average emission factor (AEF), the marginal power mix (MPM), the marginal system response (MSR) and an energy-model-derived marginal power plant (MPP). For generic and battery storage systems, a linear optimization on two levels optimizes the economic and environmental storage dispatch for a set of 50 small and medium enterprises in Germany. The four different emission factors have different signaling effects. The AEF leads to the lowest CO2 reduction and allows for roughly two daily cycles. The other EFs show a higher volatility, which leads to a higher utilization of the storage system from 3.4 to 5.4 daily cycles. The minimum mean value for CO2 abatement costs over all 50 companies is 14.13 €/t CO2 .

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