United Arab Emirates

About 95% of the hydrogen presently produced is from natural gas and coal and the remaining 5% is generated as a by-product from the production of chlorine through electrolysis1 . In the hydrogen economy (Crabtree et al. 2004; Penner 2006; Marbán and Valdés-Solís 2007) hydrogen is produced entirely from renewable energy. The easiest approach to advance renewable energy production is through solar photovoltaic and electrolysis a pathway of high technology readiness level (TRL) suffering however from two downfalls. First of all electricity is already an energy carrier and transformation with a penalty into another energy carrier hydrogen is in principle flawed. The second problem is that the efficiency of commercial solar panels is relatively low. The cadmium telluride (CdTe) thin-film solar cells have a solar energy conversion efficiency of 17%. Production of hydrogen using the current best processes for water electrolysis has an efficiency of ∼70%. As here explained the concentrated solar energy may be used to produce hydrogen using thermochemical water-splitting cycles at much global higher efficiency (fuel energy to incident sun energy). This research and development (R&D) effort is therefore undertaken to increase the TRL of this approach as a viable and economical option.

Recently with the large-scale integration of renewable energy sources into microgrid (µGs) power electronics distributed energy systems have gained popularity. However low inertia reduces system frequency stability and anti-disturbance capabilities exposing power quality to intermittency and uncertainty in photovoltaics or wind turbines. To ensure system stability the virtual inertia control (VIC) is presented. This paper proposes two solutions to overcome the low inertia problem and the surplus in capacities resulting from renewable energy sources. The first solution employs superconducting magnetic energy storage (SMES) which can be deemed as an efficient solution for damping the frequency oscillations. Therefore in this work SMES that is managed by a simple proportional-integral-derivative controller (PID) controller is utilized to overcome the low inertia. In the second solution the hydrogen storage system is employed to maintain the stability of the microgrid by storing surplus power generated by renewable energy sources (RESs). Power-to-Power is a method of storing excess renewable energy as chemical energy in the form of hydrogen. Hydrogen can be utilized locally or delivered to a consumption node. The proposed µG operation demonstrates that the integration of the photovoltaics (PVs) wind turbines (WTs) diesel engine generator (DEG) electrolyzer micro gas turbine (µGT) and SMES is adequate to fulfill the load requirements under transient operating circumstances such as a low and high PV output power as well as to adapt to sudden changes in the load demand. The effectiveness of the proposed schemes is confirmed using real irradiance data (Benban City Egypt) using a MATLAB/SIMULINK environment.

On average the shipping sector is responsible for 3% of annual global green-house gas emissions on a CO2-equivalent basis. International shipping represents around 9% of the global emissions associated with the transport sector.<br/>This report from the International Renewable Energy Agency (IRENA) explores the impact of maritime shipping on CO2 emissions the structure of the shipping sector and key areas that need to be addressed to reduce the sector’s carbon footprint.<br/>There is no clear-cut path to decarbonisation. Cutting CO2 emissions in half is therefore likely to require a combination of approaches including the use of alternative fuels upgrading of onshore infrastructure and reducing fuel demand by improving operational performance the report finds.<br/>The shipping sector is strategically important for global efforts against climate change and could be crucial in the long-term shift to a zero-carbon economy. Large-scale deployment of low-carbon fuel infrastructure for shipping could also help to build the necessary momentum to decarbonise other sectors.

Offshore renewable energy – including offshore wind and solar power as well as emerging ocean energy technologies – could support sustainable long-term development and drive a vibrant blue economy. For countries and communities around the world offshore renewables can provide reliable stable electricity as well as support water desalination and aquaculture.

This report from the International Renewable Energy Agency (IRENA) considers the status and prospects of offshore renewable sources and recommends key actions to accelerate their uptake.

The development of renewable sources and technologies at sea promises to spur new industries and create jobs in line with the global energy transition. Offshore wind towers with either fixed or floating foundations and floating solar photovoltaic (PV) arrays offer clear technological and logistical synergies with the existing offshore oil and gas industry.

Offshore renewables could provide clean power and ensure energy security for small island developing states (SIDS) and many of the least-developed countries (LDCs).

Among other findings:

• The predictability of power generation from ocean energy technologies complements the variable character solar PV and wind.
• Desalination of seawater using renewable energy sources – including solar and wind power but also direct solar and geothermal heat – can further enhance the sustainable blue economy.
• Renewable-based shipping powered with advanced biofuels hydrogen or synthetic fuels as alternatives to oil offer further synergies with offshore renewable energy.
• Islands and coastal territories could adopt renewable-based electric propulsion for short-distance (< 100 km) sea transport.
• Two reports released concurrently examine the potential for offshore renewables:

Heating and cooling accounts for almost half of global energy consumption. With most of this relying fossil fuels however it contributes heavily to greenhouse gas emissions and air pollution. In parts of the world lacking modern energy access meanwhile inefficient biomass use for cooking also harms people’s health damages the environment and reduces social well-being.



The transition to renewable-based energy-efficient heating and cooling could follow several possible pathways depending on energy demand resource availability and the needs and priorities of each country or region. Broad options include electrification with renewable power renewable-based gases (including “green” hydrogen) sustainable bioenergy use and the direct use of solar and geothermal heat.



This report developed jointly by the International Renewable Energy Agency (IRENA) the International Energy Agency (IEA) and the Renewable Energy Policy Network for the 21st Century (REN21) outlines the infrastructure and policies needed with each transition pathway. This edition focused on renewable-based heating and cooling follows a broader initial study Renewable Energy Policies in a Time of Transition (IRENA IEA and REN21 2018).



The shift to renewables for heating and cooling requires enabling infrastructure (e.g. gas grids district heating and cooling networks) as well as various combinations of deployment integrating and enabling policies. The policy framework can demonstrate a country’s commitment to the energy transition level the playing field with fossil fuels and create the necessary enabling conditions to attract investments.



Along with highlighting country experiences and best practices the study identifies barriers and highlights policy options for renewable heating and cooling.



Key recommendations include:

• Setting specific targets and developing an integrated long-term plan for the decarbonisation of heating and cooling in all end-uses including buildings industry and cooking and productive uses in areas with limited energy access.
• Creating a level playing field by phasing out fossil-fuel subsidies and introducing other fiscal policies to internalise environmental and socio-economic costs.
• Combining the electrification of heating and cooling with increasingly cost-competitive renewable power generation scaling up solar and wind use and boosting system flexibility via energy storage heat pumps and efficient electric appliances.
• Harnessing existing gas networks to accommodate renewable gases such as biogas and green hydrogen.
• Introducing standards certification and testing policies to promote the sustainable use of biomass combining efficient systems and bioenergy solutions such as pellets briquettes bioethanol or anaerobic digestion.
• Reducing investment risks for geothermal exploration and scaling up direct use of geothermal heat.
• Improving district heating and cooling networks through energy efficiency measures and the integration of low-temperature solar thermal geothermal and other renewable-based heat sources.
• Supporting clean cooking and introducing renewable-based food drying in areas lacking energy access with a combination of financing mechanisms capacity building and quality standards aimed at improving livelihoods and maximising socio-economic benefits.

As the world strives to cut carbon emissions electric power from renewables has emerged as a vital energy source. Yet transport and industry will still require combustible fuels for many purposes. Such needs could be met with hydrogen which itself can be produced using renewable power.



Hydrogen provides high-grade heat helping to meet a range of energy needs that would be difficult to address through direct electrification. This could make hydrogen the missing link in the transformation of the global energy system.  



Key sectors for renewable-based hydrogen uptake include:  

• Industry where it could replace fossil-based feedstocks including natural gas in high-emission applications.
• Buildings and power where it could be mixed with natural gas or combined with industrial carbon dioxide (CO2) emissions to produce syngas.
• Transport where it can provide low-carbon mobility through fuel-cell electric vehicles.  

Electrolysers – which split hydrogen and oxygen – can make power systems more flexible helping to integrate high shares of variable renewables. Power consumption for electrolysis can be adjusted to follow actual solar and wind output while producing the hydrogen needed for transport industry or injection into the gas grid.  



In the long run hydrogen could become a key element in 100% renewable energy systems. With technologies maturing actual scale-up should yield major cost reductions. The right policy and regulatory framework however remains crucial to stimulate private investment in in hydrogen production in the first place.

Increased use of renewable energy combined with intensified electrification could prove decisive for the world to meet key climate goals by 2050. This study from the International Renewable Energy Agency (IRENA) highlights immediately deployable cost-effective options for countries to fulfil climate commitments and limit the rise of global temperatures. The envisaged energy transformation would also reduce net costs and bring significant socio-economic benefits such as increased economic growth job creation and overall welfare gains.<br/>The report – the second under the Global Energy Transformation banner – expands IRENA’s comprehensive roadmap which examines technology pathways and policy implications to ensure a sustainable energy future. Ramping up electricity to over half of the global energy mix (up from one-fifth currently) in combination with renewables would reduce the use of fossil fuels responsible for most greenhouse-gas emissions.

It is now well established that electrochemical systems can optimally perform only within a narrow range of temperature. Exposure to temperatures outside this range adversely affects the performance and lifetime of these systems. As a result thermal management is an essential consideration during the design and operation of electrochemical equipment and can heavily influence the success of electrochemical energy technologies. Recently significant attempts have been placed on the maturity of cooling technologies for electrochemical devices. Nonetheless the existing reviews on the subject have been primarily focused on battery cooling. Conversely heat transfer in other electrochemical systems commonly used for energy conversion and storage has not been subjected to critical reviews. To address this issue the current study gives an overview of the progress and challenges on the thermal management of different electrochemical energy devices including fuel cells electrolysers and supercapacitors. The physicochemical mechanisms of heat generation in these electrochemical devices are discussed in-depth. Physics of the heat transfer techniques currently employed for temperature control are then exposed and some directions for future studies are provided.

Hydrogen is believed to be the future energy carrier that will reduce environmental pollution and solve the current energy crisis especially when produced from a renewable energy source. Solar energy is a renewable source that has been commonly utilized in the production process of hydrogen for years because it is inexhaustible clean and free. Generally hydrogen is produced by means of a water splitting process mainly electrolysis which requires energy input provided by harvesting solar energy. The proposed model integrates the solar harvesting system into a conventional Rankine cycle producing electrical and thermal power used in domestic applications and hydrogen by high temperature electrolysis (HTE) using a solid oxide steam electrolyzer (SOSE). The model is divided into three subsystems: the solar collector(s) the steam cycle and an electrolysis subsystem where the performance of each subsystem and their effect on the overall efficiency is evaluated thermodynamically using first and second laws. A parametric study investigating the hydrogen production rate upon varying system operating conditions (e.g. solar flux and area of solar collector) is conducted on both parabolic troughs and heliostat fields as potential solar energy harvesters. Results have shown that heliostat-based systems were able to attain optimum performance with an overall thermal efficiency of 27% and a hydrogen production rate of 0.411 kg/s whereas parabolic trough-based systems attained an overall thermal efficiency of 25.35% and produced 0.332 kg/s of hydrogen.

Combined heat and power (CHP) in a single and integrated device is concurrent or synchronized production of many sources of usable power typically electric as well as thermal. Integrating combined heat and power systems in today’s energy market will address energy scarcity global warming as well as energy-saving problems. This review highlights the system design for fuel cell CHP technologies. Key among the components discussed was the type of fuel cell stack capable of generating the maximum performance of the entire system. The type of fuel processor used was also noted to influence the systemic performance coupled with its longevity. Other components equally discussed was the power electronics. The thermal and water management was also noted to have an effect on the overall efficiency of the system. Carbon dioxide emission reduction reduction of electricity cost and grid independence were some notable advantages associated with fueling cell combined heat and power systems. Despite these merits the high initial capital cost is a key factor impeding its commercialization. It is therefore imperative that future research activities are geared towards the development of novel and cheap materials for the development of the fuel cell which will transcend into a total reduction of the entire system. Similarly robust systemic designs should equally be an active research direction. Other types of fuel aside hydrogen should equally be explored. Proper risk assessment strategies and documentation will similarly expand and accelerate the commercialization of this novel technology. Finally public sensitization of the technology will also make its acceptance and possible competition with existing forms of energy generation feasible. The work in summary showed that proton exchange membrane fuel cell (PEM fuel cell) operated at a lower temperature-oriented cogeneration has good efficiency and is very reliable. The critical issue pertaining to these systems has to do with the complication associated with water treatment. This implies that the balance of the plant would be significantly affected; likewise the purity of the gas is crucial in the performance of the system. An alternative to these systems is the PEM fuel cell systems operated at higher temperatures.