Cyprus

Hydrogen (H2) is currently used mainly in the chemical industry for the production of ammonia and methanol. Nevertheless in the near future hydrogen is expected to become a significant fuel that will largely contribute to the quality of atmospheric air. Hydrogen as a chemical element (H) is the most widespread one on the earth and as molecular dihydrogen (H2) can be obtained from a number of sources both renewable and nonrenewable by various processes. Hydrogen global production has so far been dominated by fossil fuels with the most significant contemporary technologies being the steam reforming of hydrocarbons (e.g. natural gas). Pure hydrogen is also produced by electrolysis of water an energy demanding process. This work reviews the current technologies used for hydrogen (H2) production from both fossil and renewable biomass resources including reforming (steam partial oxidation autothermal plasma and aqueous phase) and pyrolysis. In addition other methods for generating hydrogen (e.g. electrolysis of water) and purification methods such as desulfurization and water-gas shift reactions are discussed.

This review paper examines the possible pathways and possible technologies available that will help the shipping sector achieve the International Maritime Organization’s (IMO) deep decarbonization targets by 2050. There has been increased interest from important stakeholders regarding deep decarbonization evidenced by market surveys conducted by Shell and Deloitte. However deep decarbonization will require financial incentives and policies at an international and regional level given the maritime sector’s ~3% contribution to green house gas (GHG) emissions. The review paper based on research articles and grey literature discusses technoeconomic problems and/or benefits for technologies that will help the shipping sector achieve the IMO’s targets. The review presents a discussion on the recent literature regarding alternative fuels (nuclear hydrogen ammonia methanol) renewable energy sources (biofuels wind solar) the maturity of technologies (fuel cells internal combustion engines) as well as technical and operational strategies to reduce fuel consumption for new and existing ships (slow steaming cleaning and coating waste heat recovery hull and propeller design). The IMO’s 2050 targets will be achieved via radical technology shift together with the aid of social pressure financial incentives regulatory and legislative reforms at the local regional and international level.

Global efforts towards de-carbonization give rise to remarkable energy challenges which include renewable energy penetration increase and intermediate energy carriers for a sustainable transition. In order to reduce the dependence on fossil fuels alternative sources are considered by commodities to satisfy their increasing electricity demand as a consequence of a rise in population and the quantity of residential appliances in forthcoming years. The near-term trends appear to be in fuel and emission reduction techniques through the integration of carbon capture and storage and more efficient energy carriers exploiting alternative energy sources such as natural gas and hydrogen. Formulating both the fuel consumption and emission released the obtained experimental results showed that the total production cost can be reduced by making use of natural gas for the transition towards 2035’s targets. Maximum profits will be achieved with hydrogen as the only fuel in modern power plants by 2050. In this way the lowest electricity production can be achieved as well as the elimination of carbon dioxide emissions. Since the integration of renewable energy resources in the sectors of electricity heating/cooling and transportation will continuously be increased alternative feedstocks can serve as primary inputs and contribute to production cost profits improved utilization factors and further environmental achievements.

Hydrogen supplementation in diesel Compression Ignition (CI) engines is gaining more attention since it is considered as a feasible solution to tackle the challenges that are related to the emission regulations that will be applied in the forthcoming years. Such a solution is very attractive because it requires only limited modifications to the existing technology of internal combustion CI engines. To this end numerous work on the investigation of an engine’s performance and the effects of emissions when hydrogen is supplied in the engine’s cylinders has been completed by researchers. However contradictory results were found among these studies regarding the efficiency of the engine and the emission characteristics achieved compared to the diesel-only operation. The different conclusions might be attributed to the different characteristics and technology level of the engines that were utilized as well as on the chosen operational parameters. This paper aims to present an overview of the experimental studies that have examined the effects of hydrogen addition in CI four-stroke diesel engines reporting the characteristics of the utilized engines the quantities of hydrogen tested the method of hydrogen induction used as well as the operational conditions tested in order to help interested researchers to easily identify relevant and appropriate studies to perform comparisons or validations by repeating certain cases. The presented data do not include any results or conclusions from these studies. Furthermore an experimental configuration along with the appropriate modifications on a heavy-duty auxiliary generator-set engine that was recently developed by the authors for the purposes of the HYMAR project is presented.