Hydrogen technologies can play an important role in decarbonising our energy system in a variety of ways across the energy value chain. It is therefore critical to identify the strategic roles as ...well as the conditions under which hydrogen energy systems become attractive for the energy transition. In this paper, the authors present a techno-economic review of hydrogen energy systems including power-to-power, power-to-gas, hydrogen refuelling and stationary fuel cells. We focus on their optimal operation as flexible assets and we identify three actions that can foster their uptake beyond technological progress. First, we recommend optimal electricity supply with dedicated control strategies considering that electricity dominates the levelised cost of hydrogen production via electrolysis. Secondly, hydrogen can enable the further integration of traditionally independent sectors, namely electricity, heat and transport while contributing to decarbonise all. This position can also be advantageous for investors who sell heat and fuels as energy efficient products. Lastly, we examine a whole range of revenues from different products and applications which can be combined (i.e. benefit stacking) to match capital and operational expenditures. We discuss these roles in depth and we conclude that policy makers together with technology developers should elaborate smart strategies to reduce cost by scaling production, stimulate standardisation (e.g., similar to the PV industry) as well as develop new market structures and regulatory frameworks which allow hydrogen technologies to deliver multiple low carbon applications and products.
•The role of PtG, power-to-power, hydrogen refuelling and fuel cell are evaluated.•The value of various products and services offered by hydrogen systems is given.•Recommendations are given for minimising the levelised cost of electrolysis.•We review electronics and control techniques for various hydrogen energy systems.•Key strategies such as further system linkage and benefit stacking are discussed.
Power-to-gas (P2G) is a modular technology which offers several benefits to different types of networks and sectors while playing the role of mid-term and long-term energy storage. The core element ...of a P2G plant is the electrolyser which transforms low cost and/or renewable electricity into hydrogen. A thorough analysis of the implications of selecting an electrolyser technology (namely alkaline or PEM) and scale is key for understanding the performance and economic benefits of P2G plants generating hydrogen or methane.
In this study, a dynamic P2G model accounting for electrolyser ageing is presented following a bottom-up approach in which the electrolyser cell is modelled by means of its polarisation curve. This model allows to determine the performance, levelised cost and value of P2G plants purchasing electricity and selling gas in the wholesale market, depending on the system configuration under the Swiss regulatory context. The results indicate that technical and economic benefits increase with the electrolyser rating but those improvements are more marked for systems on the kW scale while levelling off for the MW scale. Higher capacity factors (by approximately 11%) are needed for PEM electrolysers compared to alkaline electrolysers in order to minimise the levelised cost.
•Alkaline versus PEM and hydrogen versus methane are compared for power-to-gas.•Wholesale electricity market operation was optimised for each configuration.•Alkaline electrolysers operated with 11% lower capacity factor than PEM systems.•The levelised cost of PEM systems was 15% higher than alkaline systems.•Internal rate of return values where higher than discount rate for the MW scale.
► Potential of bioethanol as raw material for biorefineries (to bulk chemicals). ► Multi-criteria early-stage sustainability assessment method for bio-based process. ► Screening and selection of ...bioethanol derivatives based on sustainability. ► Bioethanol derivatives categorization: favorable, promising and unfavorable. ► Sensitivity, scenarios and uncertainty analyses were performed.
The aim of this study is to present and apply a quick screening method and to identify the most promising bioethanol derivatives using an early-stage sustainability assessment method that compares a bioethanol-based conversion route to its respective petrochemical counterpart. The method combines, by means of a multi-criteria approach, quantitative and qualitative proxy indicators describing economic, environmental, health and safety and operational aspects. Of twelve derivatives considered, five were categorized as favorable (diethyl ether, 1,3-butadiene, ethyl acetate, propylene and ethylene), two as promising (acetaldehyde and ethylene oxide) and five as unfavorable derivatives (acetic acid, n-butanol, isobutylene, hydrogen and acetone) for an integrated biorefinery concept.
This paper addresses the thermal Energy Performance Gap (EPG), defined as the difference between a building's theoretical and actual energy consumption for thermal purposes (heating and hot water). ...Successful energy policies require estimates of the energy saving potential of the building stock. It is the objective of this work to analyse whether and to what extent an EPG exists in residential buildings in Switzerland. The database of the Swiss Cantonal Energy Certificate for Buildings was used, covering over 50 000 buildings.
The median EPG was found to be −11% (i.e. actual consumption lower than theoretical) but varied across ratings from 12.4% (B-label) to −40.4% (G-label). Buildings with low energy ratings tend to consume significantly less than expected, while buildings with high rating tend to consume slightly more than expected. For the A-labels buildings (0.5% of the total) an EPG of −6.2% was found, suggesting that the very high-performance buildings may be more robust to the EPG.
Simplified scenarios to illustrate the impact of this EPG on total consumption are presented, which highlight the challenge of meeting the Swiss Energy Strategy 2050 with a realistic renovation rate. The importance of low carbon heat supply for buildings is also discussed.
•Actual consumption for thermal use in Swiss dwellings is somewhat lower than expected.•Buildings with poor thermal performance consume substantially less than expected.•Buildings with high thermal performance consume somewhat more energy than expected.•A range of consumption was observed among buildings with identical energy rating.•It is impossible to achieve the energy objectives set with the current renovation rate.
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•A PEM electrolyser only accounts for up to 25% of the total levelized cost.•P2H offers lower environmental impacts than conventional production in most scenarios.•P2H and P2M must ...use clean electricity in order to provide environmental benefits.•Biogas upgrading reduces the environmental impacts by 2–9% regarding CO2 capture.•Increasing system scale improves both economic and environmental performance.
Interest in power-to-gas (P2G) as an energy storage technology is increasing, since it allows to utilise the existing natural gas infrastructure as storage medium, which reduces capital investments and facilitates its deployment. P2G systems using renewable electricity can also substitute for fossil fuels used for heating and transport. In this study, both techno-economic and life cycle assessment (LCA) are applied to determine key performance indicators for P2G systems generating hydrogen or methane (synthetic natural gas – SNG) as main products. The proposed scenarios assume that P2G systems participate in the Swiss wholesale electricity market and include several value-adding services in addition to the generation of low fossil-carbon gas.
We find that none of the systems can compete economically with conventional gas production systems when only selling hydrogen and SNG. For P2G systems producing hydrogen, four other services such as heat and oxygen supply are needed to ensure the economic viability of a 1MW P2H system. CO2 captured from the air adds $50/MWht of extra levelised cost to SNG compared to CO2 supplied from biogas upgrading plants and it does not offer an economic case yet regardless of the number of services. As for environmental performance, only the input of “clean” renewable electricity to electrolysis result in environmental benefits for P2G compared to conventional gas production. In particular, more than 90% of the life cycle environmental burdens are dominated by the electricity supply to electrolysis for hydrogen production, and the source of CO2 in case of SNG.
•Pb-acid and Li-ion batteries are compared under three different retail tariffs.•The battery ageing, i.e. capacity and discharge capability reduction is simulated.•A dynamic tariff (1-h resolution) ...increases the battery discharge value up to 28%.•A Li-ion cost of 375CHF/kWh is required for Geneva for PV energy time-shift.•This requirement becomes 500CHF/kWh if demand peak-shaving is also performed.
The use of batteries in combination with PV systems in single homes is expected to become a widely applied energy storage solution. Since PV system cost is decreasing and the electricity market is constantly evolving there is marked interest in understanding the performance and economic benefits of adding battery systems to PV generation under different retail tariffs. The performance of lead-acid (PbA) and lithium-ion (Li-ion) battery systems in combination with PV generation for a single home in Switzerland is studied using a time-dependant analysis. Firstly, the economic benefits of the two battery types are analysed for three different types of tariffs, i.e. a dynamic tariff based on the wholesale market (one price per hour for every day of the year), a flat rate and time-of-use tariff with two periods. Secondly, the reduction of battery capacity and annual discharge throughout the battery lifetime are simulated for PbA and Li-ion batteries. It was found that despite the levelised value of battery systems reaches up to 28% higher values with the dynamic tariff compared to the flat rate tariff, the levelised cost increases by 94% for the dynamic tariff, resulting in lower profitability. The main reason for this is the reduction of equivalent full cycles performed with by battery systems with the dynamic tariff. Economic benefits also depend on the regulatory context and Li-ion battery systems were able to achieve internal rate of return (IRR) up to 0.8% and 4.3% in the region of Jura (Switzerland) and Germany due to higher retail electricity prices (0.25CHF/kWh and 0.35CHF/kWh respectively) compared to Geneva (0.22CHF/kWh) where the maximum IRR was equal to −0.2%.
•Review of environmental, economic, social performance of electric two-wheelers.•Electric two-wheelers are more efficient and environmentally friendly than conventionally-powered vehicles.•The ...specific price of e-bikes has been declining at a learning rate of 8%.
Electrification is widely considered as a viable strategy for reducing the oil dependency and environmental impacts of road transportation. In pursuit of this strategy, most attention has been paid to electric cars. However, substantial, yet untapped, potentials could be realized in urban areas through the large-scale introduction of electric two-wheelers. Here, we review the environmental, economic, and social performance of electric two-wheelers, demonstrating that these are generally more energy efficient and less polluting than conventionally-powered motor vehicles. Electric two-wheelers tend to decrease exposure to pollution as their environmental impacts largely result from vehicle production and electricity generation outside of urban areas. Our analysis suggests that the price of e-bikes has been decreasing at a learning rate of 8%. Despite price differentials of 5000±1800EUR2012kWh−1 in Europe, e-bikes are penetrating the market because they appear to offer an apparent additional use value relative to bicycles. Mid-size and large electric two-wheelers do not offer such an additional use value compared to their conventional counterparts and constitute niche products at price differentials of 700±360EUR2012kW−1 and 160±90EUR2012kW−1, respectively. The large-scale adoption of electric two-wheelers can reduce traffic noise and road congestion but may necessitate adaptations of urban infrastructure and safety regulations. A case-specific assessment as part of an integrated urban mobility planning that accounts, e.g., for the local electricity mix, infrastructure characteristics, and mode-shift behavior, should be conducted before drawing conclusions about the sustainability impacts of electric two-wheelers.
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•Method is proposed to evaluate batteries combining applications for consumers.•Electricity demand input data have 1 min resolution across 100 dwellings.•The lithium-ion battery model ...includes ageing throughout the battery lifetime.•Couple of storage applications are classified as complementary or substitutive.•Results show the importance of the electricity demand for combining applications.
Batteries are expected to play an important role in the transition to decarbonised energy systems by enabling the further penetration of renewable energy technologies while assuring grid stability. However, their hitherto high capital costs is a key barrier for their further deployment. In order to improve their economic viability, batteries could provide several applications offering revenues. The techno-economic evaluation of batteries simultaneously serving several applications has proven to be challenging due to the trade-offs between energy and power applications. Focusing on residential batteries, we develop an optimisation method for designing optimal value propositions and we test it for four different applications both individually and jointly: PV self-consumption, demand load-shifting, avoidance of PV curtailment and demand peak shaving. Our results show that the combination of all applications currently helps batteries to get closer to profitability, from a net present value (NPV) per unit of capital expenditure (CAPEX) of −0.63 ± 0.04 for PV self-consumption only to −0.36 ± 0.10, with the combination of demand peak-shaving and PV self-consumption adding most value (0.21 ± 0.04). We also find that the annual household’s electricity consumption determines the value of energy storage applications. The proposed method allow us to classify storage applications as complementary and substitutive depending on whether their combined application increases their economic attractiveness or not. These results thus offer valuable insight for stakeholders interested in the deployment of energy storage in combination with energy efficiency, heat pumps and electric vehicles such as consumers, utility companies and policy makers.
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