Publications

The study of the viability of hydrogen production as a sustainable energy source is a current challenge to satisfy the great world energy demand. There are several techniques to produce hydrogen either mature or under development. The election of the hydrogen production method will have a high impact on practical sustainability of the hydrogen economy. An important profile for the viability of a process is the calculation of energy and exergy efficiencies as well as their overall integration into the circular economy. To carry out theoretical energy and exergy analyses we have estimated proposed hydrogen production using different software (DWSIM and MATLAB) and reference conditions. The analysis consolidates methane reforming or auto-thermal reforming as the viable technologies at the present state of the art with reasonable energy and exergy efficiencies but pending on the impact of environmental constraints as CO2 emission countermeasures. However natural gas or electrolysis show very promising results and should be advanced in their technological and maturity scaling. Electrolysis shows a very good exergy efficiency due to the fact that electricity itself is a high exergy source. Pyrolysis exergy loses are mostly in the form of solid carbon material which has a very high integration potential into the hydrogen economy.

The effects of climate change and global warming are arising a new awareness on the impact of our daily life. Power generation for transportation and mobility as well as in industry is the main responsible for the greenhouse gas emissions. Indeed currently 80% of the energy is still produced by combustion of fossil fuels; thus great efforts need to be spent to make combustion greener and safer than in the past. For this reason a review of the most recent gas turbines combustion strategy with a focus on fuels combustion techniques and burners is presented here. A new generation of fuels for gas turbines are currently under investigation by the academic community with a specific concern about production and storage. Among them biofuels represent a trustworthy and valuable solution in the next decades during the transition to zero carbon fuels (e.g. hydrogen and ammonia). Promising combustion techniques explored in the past and then abandoned due to their technological complexity are now receiving renewed attention (e.g. MILD PVC) thanks to their effectiveness in improving the efficiency and reducing emissions of standard gas turbine cycles. Finally many advances are illustrated in terms of new burners developed for both aviation and power generation. This overview points out promising solutions for the next generation combustion and opens the way to a fast transition toward zero emissions power generation.

A rigorous heterogeneous mathematical model is used to simulate a cascade of multi-stage fixed bed membrane reactors (MSFBMR) with inter-stage heating and fresh sweep gas for the decomposition of ammonia to produce high purity hydrogen suitable for the PEM fuel cells. Different reactor configurations are compared. The comparison between a single fixed bed reactor (FBR) and a single fixed bed membrane reactor (FBMR) shows that the FBMR is superior to the FBR and gives 60.48% ammonia conversion higher than the FBR. However 20.91% exit ammonia conversion obtained by the FBMR is considered to be poor. The FBMR is limited by the kinetics at low temperatures. The numerical results show that the MSFBMR of four beds achieve 100.0% ammonia conversion. It was found that the membrane plays the prime role in the displacement of the thermodynamic equilibrium. The results also show that a linear relationship exists between the number of beds and the feed temperature and a correlation has been developed. A critical point for an effective hydrogen permeation zone has been identified. It is observed that the diffusion limitation is confined to a slim region at the entrance of the reactor. It is also observed that the heat load assumes a maximum inflection point and explanations offered. The results show that the multi-stage configuration has a promising potential to be applied successfully on-site for ultra-clean hydrogen production.

A steady state analysis method was developed for gas networks with distributed injection of alternative gas. A low pressure gas network was used to validate the method. Case studies were carried out with centralized and decentralized injection of hydrogen and upgraded biogas. Results show the impact of utilizing a diversity of gas supply sources on pressure distribution and gas quality in the network. It is shown that appropriate management of using a diversity of gas supply sources can support network management while reducing carbon emissions.

In the present study hydrogen utilization as diesel engine fuel at low load operation was investigated. Hydrogen cannot be used directly in a diesel engine due to its auto ignition temperature higher than that of diesel fuel. One alternative method is to use hydrogen in enrichment or induction. To investigate the combustion characteristics of this dual fuel engine a single cylinder diesel research engine was converted to utilize hydrogen as fuel. Hydrogen was introduced to the intake manifold using a mixer before entering the combustion chamber. The engine was run at a constant speed of 2000 rpm and 10 Nm load. Hydrogen was introduced at the flow rate of 21.4 36.2 and 49.6 liter/minute. Specific energy consumption indicated efficiency and cylinder pressure were investigated. At this low load the hydrogen enrichment reduced the cylinder peak pressure and the engine efficiency. The reaction progress variable and combustion rate of reaction were slower as shown by the CFD calculation.

Solar photovoltaic (PV) plants coupled with storage for domestic self-consumption purposes seem to be a promising technology in the next years as PV costs have decreased significantly and national regulations in many countries promote their installation in order to relax the energy requirements of power distribution grids. However electrochemical storage systems are still unaffordable for many domestic users and thus the advantages of self-consumption PV systems are reduced. Thus in this work the adoption of hydrogen systems as energy vectors between a PV plant and the energy user is proposed. As a preliminary study in this work the design of a PV and hydrogen-production self-consumption plant for a single dwelling is described. Then a technical and economic feasibility study conducted by modeling the facility within the Homer Energy Pro energy systems analysis tool is reported. The proposed system will be able to provide back not only electrical energy but also thermal energy through a fuel cell or refined water covering the fundamental needs of the householders (electricity heat or cooling and water). Results show that although the proposed system effectively increases the energy local use of the PV production and reduces significantly the energy injections or demands into/from the power grid avoiding power grid congestions and increasing the nano-grid resilience operation and maintenance costs may reduce its economic attractiveness for a single dwelling.

Decarbonisation of heating and road transport are regarded as necessary but very challenging steps on the pathway to net zero carbon emissions. Assessing the most efficient routes to decarbonise these sectors requires an integrated view of energy and road transport systems. Here we describe how a national gas and electricity transmission network model was extended to represent multiple local energy systems and coupled with a national energy demand and road transport model. The integrated models were applied to assess a range of technologies and policies for heating and transport where the UK’s 2050 net zero carbon emissions target is met. Overall annual primary energy use is projected to reduce by between 25% and 50% by 2050 compared to 2015 due to ambitious efficiency improvements within homes and vehicles. However both annual and peak electricity demands in 2050 are more than double compared with 2015. Managed electric vehicle charging could save 14TWh/year in gas-fired power generation at peak times and associated emissions whilst vehicle-to-grid services could provide 10GW of electricity supply during peak hours. Together managed vehicle charging and vehicle-to-grid supplies could result in a 16% reduction in total annual energy costs. The provision of fast public charging facilities could reduce peak electricity demand by 17GW and save an estimated £650 million annually. Although using hydrogen for heating and transport spreads the hydrogen network costs between homeowners and motorists it is still estimated to be more costly overall compared to an all-electric scenario. Bio-energy electricity generation plants with carbon capture and storage are required to drive overall energy system emissions to net zero utilisation of which is lowest when heating is electrified and road transport consists of a mix of electric and hydrogen fuel-cell vehicles. The analysis demonstrates the need for an integrated systems approach to energy and transport policies and for coordination between national and local governments.

A paradigm shift towards the utilization of carbon-neutral and low emission fuels is necessary in the internal combustion engine industry to fulfil the carbon emission goals and future legislation requirements in many countries. Hydrogen as an energy carrier and main fuel is a promising option due to its carbon-free content wide flammability limits and fast flame speeds. For spark-ignited internal combustion engines utilizing hydrogen direct injection has been proven to achieve high engine power output and efficiency with low emissions. This review provides an overview of the current development and understanding of hydrogen use in internal combustion engines that are usually spark ignited under various engine operation modes and strategies. This paper then proceeds to outline the gaps in current knowledge along with better potential strategies and technologies that could be adopted for hydrogen direct injection in the context of compression-ignition engine applications—topics that have not yet been extensively explored to date with hydrogen but have shown advantages with compressed natural gas.

Considering energy crises and pollution problems today much work has been done for alternative fuels for fossil fuels and lowering the toxic components in the combustion products. Expert studies proved that hydrogen one of the prominent alternative energy source which has many excellent combustion properties that can be used for improving combustion and emissions performance of gasoline-fuelled spark ignition (SI) engines. This article experimentally investigated the performance and emission characteristics of a high speed single cylinder SI engine operating with different hydrogen gasoline blends. For this purpose the conventional carburetted high speed SI engine was modified into an electronically controllable engine with help of electronic control unit (ECU) which dedicatedly used to control the injection timings and injection durations of gasoline. Various hydrogen enrichment levels were selected to investigate the effect of hydrogen addition on engine brake mean effective pressure (Bmep) brake thermal efficiency volumetric efficiency and emission characteristics. The test results demonstrated that combustion performances fuel consumption and brake mean effective pressure were eased with hydrogen enrichment. The experimental results also showed that the brake thermal efficiency was higher than that for the pure gasoline operation. Moreover HC and CO emissions were all reduced after hydrogen enrichment.

Transport is one of the key sectors of the European economy. However the intensive development of transport caused negative effects in the form of an increase in the emission of harmful substances. The particularly dramatic situation took place in the V4 countries. This made it necessary to implement solutions reducing emissions in transport including passenger transport. Such activities can be implemented in the field of implementation of low-emission and zero-emission vehicles for use. That is why the European Union and the governments of the Visegrad Group countries have developed numerous recommendations communications laws and strategies that order carriers to implement low- and zero-emission mobility. Therefore transport organizers and communication operators faced the choice of the type of buses. From an economic point of view each entrepreneur is guided by the economic efficiency of the vehicles used. Hence the main aim of the article was to conduct an economic evaluation of the operational efficiency of ecological vehicles. As more than 70% of vehicles in use in the European Union are still diesel driven the economic efficiency assessment was also made for vehicles with traditional diesel drive. To conduct the research the method of calculating the total cost of ownership of vehicles in operation was used. As a result of the research it was found that electric buses are the cheapest in the entire period of use (15 years) and then those powered by CNG. On the other hand the cost of using hydrogen buses is the highest. This is due to the high purchase prices of these vehicles. However the EU as well as the governments of individual countries support enterprises and communication operators by offering them financing for investments. The impact of the forecasted fuel and energy prices and the planned inflation on operating costs was also examined. In this case the analyses showed that the forecasted changes in fuel and energy prices as well as the expected inflation will significantly affect the costs of vehicle operation and the economic efficiency of using various types of drives. These changes will have a positive impact on the implementation of zero-emission vehicles into exploitation. Based on the analyses it was found that in 2035 hydrogen buses will have the lowest operating costs.