Publications

Decarbonising energy is fundamental in the transition towards a sustainable future. Our Future Energy Scenarios aim to stimulate debate to inform the decisions that will help move us towards achieving carbon reduction targets and ultimately shape the energy system of the future.

Supporting policies to achieve a green revolution and ecological transition is a global trend. Although the maritime transport of goods and people can rightly be counted among the least polluting sectors much can be done to further reduce its environmental footprint. Moreover to boost the ecological transition of vessels a whole series of international regulations and national laws have been promulgated. Among these the most impactful on both design and operational management of ships concern the containment of air-polluting emissions in terms of GHG NOx SOx and PM. To address this challenge it might seem that many technologies already successfully used in other transport sectors could be applied. However the peculiar characteristics of ships make this statement not entirely true. In fact technological solutions recently adopted for example in the automotive sector must deal with the large size of vessels and the consequent large amount of energy necessary for their operation. In this paper with reference to the case study of a medium/large-sized passenger cruise ship the use of different fuels (LNG ammonia hydrogen) and technologies (internal combustion engines fuel cells) for propulsion and energy generation on board will be compared. By imposing the design constraint of not modifying the payload and the speed of the ship the criticalities linked to the use of one fuel rather than another will be highlighted. The current limits of application of some fuels will be made evident with reference to the state of maturity of the relevant technologies. Furthermore the operational consequences in terms of autonomy reduction will be presented. The obtained results underline the necessity for shipowners and shipbuilders to reflect on the compromises required by the challenges of the ecological transition which will force them to choose between reducing payload or reducing performance.

Traditional charging stations have a single function which usually does not consider the construction of energy storage facilities and it is difficult to promote the consumption of new energy. With the gradual increase in the number of new energy vehicles (NEVs) to give full play to the complementary advantages of source-load resources and provide safe efficient and economical energy supply services this paper proposes the optimal operation strategy of a PV-charging-hydrogenation composite energy station (CES) that considers demand response (DR). Firstly the operation mode of the CES is analyzed and the CES model including a photovoltaic power generation system fuel cell hydrogen production hydrogen storage hydrogenation and charging is established. The purpose is to provide energy supply services for electric vehicles (EVs) and hydrogen fuel cell vehicles (HFCVs) at the same time. Secondly according to the travel law of EVs and HFCVs the distribution of charging demand and hydrogenation demand at different periods of the day is simulated by the Monte Carlo method. On this basis the following two demand response models are established: charging load demand response based on the price elasticity matrix and interruptible load demand response based on incentives. Finally a multi-objective optimal operation model considering DR is proposed to minimize the comprehensive operating cost and load fluctuation of CES and the maximum–minimum method and analytic hierarchy process (AHP) are used to transform this into a linearly weighted single-objective function which is solved via an improved moth–flame optimization algorithm (IMFO). Through the simulation examples operation results in four different scenarios are obtained. Compared with a situation not considering DR the operation strategy proposed in this paper can reduce the comprehensive operation cost of CES by CNY 1051.5 and reduce the load fluctuation by 17.8% which verifies the effectiveness of the proposed model. In addition the impact of solar radiation and energy recharge demand changes on operations was also studied and the resulting data show that CES operations were more sensitive to energy recharge demand changes.

Tropical countries can approach their natural resources to produce low-carbon H2 from solar wind hydro and biomass resources to satisfy their domestic demand and to export it. To do so Colombia published the National Hydrogen Roadmap in which green H2 was prioritized. This study estimates Colombia's potential to produce green H2 and a timeline of scenarios displaying the required installed capacity capital investment and environmental analysis related to water utilization and CO2 capture. Accordingly Colombia can produce H2 at a rate of 9 Mt/a by 2050 by installing 121 GW renewables while processing 303 Mt/a of residual biomass. In this scenario Colombia's share of the H2 international market can reach 1.2% with a cumulative investment of over 244 billion USD by 2050. This study provides insights into potential global resources for low-carbon H2 generation.

Hydrogen has recently been proposed as a versatile energy carrier to contribute to archiving universal access to clean cooking. In hard-to-reach rural settings decentralized produced hydrogen may be utilized (i) as a clean fuel via direct combustion in pure gaseous form or blended with Liquid Petroleum Gas (LPG) or (ii) via power-to-hydrogen-to-power (P2H2P) to serve electric cooking (e-cooking) appliances. Here we present the first techno-economic evaluation of hydrogen-based cooking solutions. We apply mathematical optimization via energy system modeling to assess the minimal cost configuration of each respective energy system on technical and economic measures under present and future parameters. We further compare the potential costs of cooking for the end user with the costs of cooking with traditional fuels. Today P2H2P-based e-cooking and production of hydrogen for utilization via combustion integrated into the electricity supply system have almost equal energy system costs to simultaneously satisfy the cooking and electricity needs of the isolated rural Kenyan village studied. P2H2P-based e-cooking might become advantageous in the near future when improving the energy efficiency of e-cooking appliances. The economic efficiency of producing hydrogen for utilization by end users via combustion benefits from integrating the water electrolysis into the electricity supply system. More efficient and cheaper hydrogen technologies expected by 2050 may improve the economic performance of integrated hydrogen production and utilization via combustion to be competitive with P2H2P-based e-cooking. The monthly costs of cooking per household may be lower than the traditional use of firewood and charcoal even today when applying the current life-line tariff for the electricity consumed or utilizing hydrogen via combustion. Driven by likely future technological improvements and the expected increase in traditional and fossil fuel prices any hydrogen-based cooking pathway may be cheaper for end users than using charcoal and firewood by 2030 and LPG by 2040. The results suggest that providing clean cooking in rural villages could economically and environmentally benefit from utilizing hydrogen. However facing the complexity of clean cooking projects we emphasize the importance of embedding the results of our techno-economic analysis in holistic energy delivery models. We propose useful starting points for future aspects to be investigated in the discussion section including business and financing models.

Although polymer electrolyte water electrolyzers (PEWEs) have been used in small-scale (kW to tens of kW range) applications for several decades PEWE technology for hydrogen production in energy applications (power-to-gas power-to-fuel etc.) requires significant improvements in the technology to address the challenges associated with cost performance and durability. Systems with power of hundreds of kW or even MWs corresponding to hydrogen production rates of around 10 to 20 kg/h have started to appear in the past 5 years. The thin (∼0.2 mm) polymer electrolyte in the PEWE with low ohmic resistance compared to the alkaline cell with liquid electrolyte allows operation at high current densities of 1–3 A/cm2 and high differential pressure. This article after an introductory overview of the operating principles of PEWE and state-of-the-art discusses the state of understanding of key phenomena determining and limiting performance durability and commercial readiness identifies important ‘gaps’ in understanding and essential development needs to bring PEWE science & engineering forward to prosper in the energy market as one of its future backbone technologies. For this to be successful science engineering and process development as well as business and market development need to go hand in hand.

Electrochemical ammonia generation allows direct low pressure synthesis of ammonia as an alternative to the established Haber-Bosch process. The increasing need to drive industry with renewable electricity central to decarbonisation and electrochemical ammonia synthesis offers a possible efficient and low emission route for this increasingly important chemical. It also provides a potential route for more distributed and small-scale ammonia synthesis with a reduced production footprint. Electrochemical ammonia synthesis is still early stage but has seen recent acceleration in fundamental understanding. In this work two different ammonia electrolysis systems are considered. Balance of plant (BOP) requirements are presented and modelled to compare performance and determine trade-offs. The first option (water fed cell) uses direct ammonia synthesis from water and air. The second (hydrogen-fed cell) involves a two-step electrolysis approach firstly producing hydrogen followed by electrochemical ammonia generation. Results indicate that the water fed approach shows the most promise in achieving low energy demand for direct electrochemical ammonia generation. Breaking the reaction into two steps for the hydrogen fed approach introduces a source of inefficiency which is not overcome by reduced BOP energy demands and will only be an attractive pathway for reactors which promise both high efficiency and increased ammonia formation rate compared to water fed cells. The most optimised scenario investigated here with 90% faradaic efficiency (FE) and 1.5 V cell potential (75% nitrogen utilisation) gives a power to ammonia value of 15 kWh/kg NH3 for a water fed cell. For the best hydrogen fed arrangement the requirement is 19 kWh/kg NH3. This is achieved with 0.5 V cell potential and 75% utilisation of both hydrogen and nitrogen (90% FE). Modelling demonstrated that balance of plant requirements for electrochemical ammonia are significant. Electrochemical energy inputs dominate energy requirements at low FE however in cases of high FE the BOP accounts for approximately 50% of the total energy demand mostly from ammonia separation requirements. In the hydrogen fed cell arrangement it was also demonstrated that recycle of unconverted hydrogen is essential for efficient operation even in the case where this increases BOP energy inputs

Alternative fuels are crucial to decarbonize the European maritime transport but their net climate benefits vary with the type of fuel and production country. In this study we assess the energy potential and climate change mitigation benefits of using agricultural and forest residues in different European countries for drop-in (Fast Pyrolysis Hydrothermal Liquefaction and Gasification to Fischer-Tropsch fuels or Bio-Synthetic Natural Gas) and hydrogen-based biofuels (hydrogen ammonia and methanol) with or without carbon capture and storage (CCS). Our results show the combinations of countries and biofuel options that successfully achieve the decarbonization targets set by the FuelEU Maritime initiative for the next years including a prospective analysis that include technological changes projected for the biofuel supply chains until 2050. With the current technologies the largest greenhouse gas (GHG) mitigation potential per year at a European scale is obtained with bio-synthetic natural gas and hydrothermal liquefaction. Among carbon-free biofuels ammonia currently has higher mitigation but hydrogen can achieve a lower GHG intensity per unit of energy with the projected decarbonization of the electricity mixes until 2050. The full deployment of CCS can further accelerate the decarbonization of the maritime sector. Choosing the most suitable renewable fuels requires a regional perspective and a transition roadmap where countries coordinate actions to meet ambitious climate targets.

Ammonia (NH3) is among the largest-volume chemicals produced and distributed in the world and is mainly known for its use as a fertilizer in the agricultural sector. In recent years it has sparked interest in the possibility of working as a high-quality energy carrier and as a carbon-free fuel in internal combustion engines (ICEs). This review aimed to provide an overview of the research on the use of green ammonia as an alternative fuel for ICEs with a look to the future on possible applications and practical solutions to related problems. First of all the ammonia production process is discussed. Present ammonia production is not a “green” process; the synthesis occurs starting from gaseous hydrogen currently produced from hydrocarbons. Some ways to produce green ammonia are reviewed and discussed. Then the chemical and physical properties of ammonia as a fuel are described and explained in order to identify the main pros and cons of its use in combustion systems. Then the most viable solutions for fueling internal combustion engines with ammonia are discussed. When using pure ammonia high boost pressure and compression ratio are required to compensate for the low ammonia flame speed. In spark-ignition engines adding hydrogen to ammonia helps in speeding up the flame front propagation and stabilizing the combustion. In compression-ignition engines ammonia can be successfully used in dual-fuel mode with diesel. On the contrary an increase in NOx and the unburned NH3 at the exhaust require the installation of apposite aftertreatment systems. Therefore the use of ammonia seems to be more practicable for marine or stationary engine application where space constraints are not a problem. In conclusion this review points out that ammonia has excellent potential to play a significant role as a sustainable fuel for the future in both retrofitted and new engines. However significant further research and development activities are required before being able to consider large-scale industrial production of green ammonia. Moreover uncertainties remain about ammonia safe and effective use and some technical issues need to be addressed to overcome poor combustion properties for utilization as a direct substitute for standard fuels.

The report “Policy Toolbox for Low Carbon and Renewable Hydrogen” is based on an assessment of the performance of hydrogen policies in different stages of market maturity and segments of the value chain. 48 policies were shortlisted based on their economic efficiency and effectiveness and mapped to barriers across the value chain and over time. These policies were subsequently clustered into policy packages for three country archetypes: a self-sufficient hydrogen producer an importer and an exporter of hydrogen.

The paper can be found on their website.