Hydrogen farm concept: A Perspective for Turkey

Abstract

Climate change mitigation and implementing the necessary rules and regulations are terribly needed to make the global commitment stronger than ever before. On the energy side which is closely linked to these, energy market is and will be more struggling to afford turning away from fossil fuels and move into decarbonization era. Since the industrial revolution, a drastic increase in the anthropogenic carbon dioxide concentrations in the atmosphere has been observed and affected the human health and human welfare, and such anthropological effects cannot be gainsaid, despite all political-based denials and traditional fossils fuels lobbies' enforcements. An outcome of this enactment is to employ carbon-free fuels in various energy market sections, and one key solution for such a sustainable fuel is, in this regard, hydrogen which can be used as an energy carrier, a fuel, and a feedstock. Scalable hydrogen production from renewable energy resources facilitates the road for replacing carbon-based fuels with renewable energies. Hydrogen widely exists in many things, including water, biomass, fossil fuels, but cannot be found alone in the universe. A critical question is that how to produce it in a more efficient, effective and environmentally benign manner. Considering the processing cost for hydrogen production, fossil fuel-based methods, such as steam methane reforming (SMR) appears to be less expensive than the electrolysis methods. This makes SMR much more widely used one than other renewable energy driven processes. One needs to keep in mind that about 95% of total hydrogen production comes from fossil fuels, including natural gas, oil and coal while the remaining 5% comes from electrolysis and other methods. To minimize the detrimental environmental impacts, renewable energy sources, including wind, solar, hydro, biomass, geothermal, and marine should be preferred over the traditional hydrocarbon-based hydrogen production (primarily with natural gas, coal, and oil). Dealing with renewable energy sources, particularly with solar and wind options, brings another obstacle which is the storage of intermittently generated electricity. In conjunction with this, the power-to-gas approach has recently started attracting attention where excess power is used to generate hydrogen. Its storage and distribution through the dedicated pipelines or available natural gas pipelines are still considered among the feasible solutions. In the first step, there is a need to establish a regional hydrogen hub in which, different aspects should be taken into consideration, including the availability of renewable resources, production methods, infrastructure, storage, and distribution systems. Creating a hydrogen hub, especially in developing countries where they normally have high potentials for solar, wind, and other renewable resources can bring employment and economic opportunities and secure the country against oil supply disruptions. The selection of Turkey for this purpose can be justified due to specific reasons such as its geopolitical location, being the sunniest county in Europe, the lack of fossil fuel energy sources and hence, high motivation for investment in green energy technologies. To tackle with the problem of hydrogen storage, different approaches and solution methodologies are available. Although solid-state hydrogen storage is a better choice after overwhelming the current hurdles for its widespread use, especially for the transportation sector, and in spite of the fact that gaseous and cryogenic liquid hydrogen storage looks more practical, some safety and handling limitations/concerns exist, but are more easily manageable with the existing capabilities. The main objective of the current study is to develop a hydrogen farm concept where renewable energy sources are deployed to produce green (or clean or sustainable) hydrogen using clean methods and processes, ranging from electrolysis to thermochemical cycles. An application study is undertaken for the 81 cities in seven regions of Turkey where a wide range of renewables are potentially available for hydrogen production. It therefore makes this perspective unique in concept development and making a dynamic application to the cities of Turkey. It also aims to show the importance of hydrogen farms and providing a big picture about hydrogen production potential. On a regional scale, it strengthens the countries economy, motivates heavy industries, transportation section and building industry. Globally looking, this approach to renewable energy sources accelerates the decarbonization process which is an effective way to combat global warming. Developed countries have already planned the establishment of hydrogen hub in specific zones and have studied it from different aspects such as life cycle assessment.1 The need to investigate cost-effective hydrogen storage systems can also help to transfer the related technologies to the target country that has established, such a hydrogen hub. Consequently, the long-term energy storage solutions will pave the road to a sustainable energy future, increasing the penetration of renewable energies for Turkey and also can be considered as a business plan to export the cheaper green hydrogen to the high demand countries. This trend is more pronounced if urgent plans for delivering clean energy alternatives are taken into account. Turkey, as a case study for this perspective, can also possess a unique position among other developing countries by being a pioneer in this technology, making it a leader in this market. The main idea behind the hydrogen farm concept is to provide an efficient approach to produce clean energy based on renewable energy sources. In order to pave the road for this goal, the Source, System, and Service (3S) approach is considered as the base outline.2 On the other hand, the importance of the energy storage between source-system and system-service is obvious, which leads to the concept of 4S in developing clean energy systems. Available wind and solar farms in a region are the main potential sources for renewable power production. Auxiliary available sources including geothermal, biomass, hydroelectric and wave energies form the other main components of a renewable farm from which the green hydrogen is produced. In the current perspective and among different hydrogen generation methods, water splitting through electrolysis has been considered. Alkaline electrolyser, for example, is a feasible and rather acceptable method for scalable hydrogen production. Figure 1 shows the employed renewable energy sources in the current study and the production process of green hydrogen. In this perspective, hydrogen potential for Turkey is studied. In order to have the total production potential of the whole country, the total area for each city is collected from governmental sources.3 The idea is to use the land and offshore areas for solar and wind energies, and hence the useful net area has been calculated. The urban areas,4 industrial areas,5 forestry lands6 agricultural areas4 are deduced from the whole area of each city. Another assumption is that an average 10% roofing area is dedicated to installed solar energy systems, namely photovoltaic panels. In calculating the applicable area for offshore regions, the coastline data for the applicable cities are taken into account with an assumed net width of 2 km. This narrow width is almost 30% of the offshore area in most of the regions due to the transportation corridors, and private area assumption is subjected to changes based on the international agreements along with the provided spaces. Data are provided by the Ministry of National Defence.3 The solar energy potential in different places mainly relies on the insolation values. The employed solar energy data are taken from the Ministry of Energy and Natural Resources.7 For photovoltaic systems, Polycrystalline PV panels, with an average efficiency of 15%, are considered in the calculations, mostly due to their lower costs compared with the monocrystalline panels, although the latter one has a higher efficiency. The output electric power is then used in electrolyser units. Alkaline-type electrolysers with an average efficiency of 75% are considered. Regarding wind energy, data is taken from the General Directorate of Meteorology maps and the assumption is made for a tower height of 50 m. Depending on the available areas to install the wind turbines, horizontal and vertical turbines can be used. In terms of efficiency, horizontal types have higher efficiency than vertical wind turbines. It is assumed in the current perspective that horizontal wind turbines are used. A literature review shows that the average capacity of wind turbines installed in the United States is 1.8 MW.8 For this reason, the Vestas V90-2 MW wind turbine is used in the calculations. Technical specifications of this sample wind turbine are presented in Reference [9]. For offshore applications, in general, bigger wind turbines are used, but in the current study, the same wind turbines are assumed to be used for power generating in cities with offshore. Van Lake is a big one and the government has mobile data collecting stations to monitor its offshore wind power. For the Van Lake, its two neighboring cities, namely Van and Bitlis can use the lake area for installing the solar or wind turbines, which in turn, increase their potential for hydrogen production.10 For hydro power calculation, all running dams built by the government and private companies are taken into account. The annual overall electric production data is taken from the Ministry of Agriculture and Forestry.11 Biomass energy has various forms including animal waste, forest waste, plant waste, and municipal waste. Different methods can be used to exploit this energy. Biomass sources for all Cities of Turkey can be obtained from the Ministry of Energy and Natural Resources.12 For the current research, only municipal solid waste has been considered. The main two methods provided are incineration and biometanization to generate renewable electricity. For this purpose, their Tons of Oil Equivalent energy content is used as a thermal energy source in a typical thermodynamic cycle with an average efficiency of 32%. The generated electricity, similar to the other sources, is fed into a 70% efficient alkaline electrolyser to generate hydrogen. Another considered renewable energy source is geothermal energy. Turkey is a leading country in geothermal, especially for the years up to 2015.13 Geothermal has two main roles in providing the required energy. It can be either used for space heating and cooling (through absorption cycles) or the direct flashed steam can be expanded and generate electricity. To select which application is more feasible and economic, the underground source temperature is the main criterion. In this study, for the geothermal sources with temperature between 85.80°C and 114.4°C, Rankine and Organic Rankine Cycles are exploited for electric power generation.14 Sources with a temperatures higher than 114.4°C are considered in the calculations to be used in steam turbines. Technically, the sources with a temperature around 105°C can be used for cooling applications and sources with even less exergy can be used for space heating. The geothermal potential data of the county is taken from the General Directorate of Mineral Exploration and Research, geothermal division.15 Once a source is available, the mass flow rate and temperature ranges and enthalpies for the cycle operation are following the already installed geothermal power plants. For hotter regions enthalpy difference is found using the already established geothermal power plants, the joint flow rate is calculated and power generation is used as a source for hydrogen production assuming all the geothermal plants output energy used for hydrogen production. Turkey is surrounded by seas which make it a feasible source of green hydrogen production. There are different approaches to exploit the wave energy, ranging from tidal energy due to gravity to undersea turbines. Considering the location of the cities, some of these methods are not applicable, such as tidal energy. The main two methods which are used in this study are undersea turbines and wave energy. For the wave energy, the assumed sea depth is 75 m and wave heights are calculated from sea level. Wave height (m) and wave period (s) data are taken from the General Directorate of Meteorology.11 Typical Pelamis turbines used for collecting wave energy have 2.62 GWh/year (750 kW power output) with a 0.40 capacity factor and have a length of about 150-m diameter.16 For the undersea current, Turkey does not have access to high-speed currents. Therefore, specific zones have chosen from the Black Sea,17 Hellespont,18 Mediterranean Sea,19 and Bosporus.11 Due to the lower cut-in speeds, smaller commercial undersea turbines have been entered in the calculations. In order to avoid the wake regions of consequential turbines, they are configured with a 5-m distance from each other. The total potential for each city is the sum of all possible renewable energy sources. Two scenarios are considered here. In the first scenario, we assume that all energy is used for hydrogen production. The second scenario considers the electric power consumption of cities and the extra power is then converted to hydrogen. Depending on the obtained data for each location, it is calculated that which source provides more power. For the regions that have access to coastlines and the possibility of exploiting offshore energy, wind or solar energy have been considered. For all of these cities, undersea turbines are used, as explained above. In the case of using wind turbines, the free space in the wind farms is covered with solar photovoltaic systems. One option is to replace these panels with Pelamis generators, because the results of this study show that the wave energy can give two to three times more energy to the photovoltaic panels, but they are not that much cost effective, compared to that of PV panels. Nevertheless, for Northern territories of the country, wave energy is considered because of higher wave potential. For Akdeniz region and more touristic regions, 30% of the available offshore area is used for solar energy. Maximum hydrogen potential capacity for a city in Turkey is considered as a collection of onshore solar, offshore wind, or solar depending on the area, geothermal, wave, undersea current, hydro, and biomass resources. For the first scenario, it is assumed that all the available energies are considered to be converted to hydrogen energy. This means that all solar, wind, geothermal, hydro, biomass, wave, and undersea current power is used as power to generate hydrogen using electrolyzer systems. This is mainly due to the fact that the energy format used for transportation, heating, and cooling of spaces and energy used in industry is subjected to change in the future. This strategy is also depends on the locations. Table 1 lists the total potential of hydrogen production for all cities. In the second scenario, the total electric consumption of all cities is deduced from the overall available energy. Therefore, the extra electrical energy is used for hydrogen production. Electric consumption data are taken from Energy Market Regulatory Authority monthly sector report.20 Table 2 gives the annual hydrogen production potential for Turkey after excluding the electric power consumption of cities. The energy needs of cities depend on the energy form that is used in the residential, industrial, and especially in the transportation systems. For an electrified transportation system which can be battery electrical cars or fuel cell vehicles, a major portion of the electricity is used for transportation. The same rationality is true for energy format that is used for the space heating and cooling. Therefore, after deduction of electricity for heating, cooling and industrial applications, the rest of the electrical power is used for hydrogen production and based on these values, the potential of cities for green hydrogen production will change, as can be seen in Table 2. Figure 2 illustrates a visual perspective about this potential. The values for different cities in this figure show hydrogen potential for each city, before excluding their electric power consumption. Furthermore, Figure 3 shows the hydrogen potential after providing enough power to each city. While cities with a high population use more electrical power, smaller ones need less electrical energy, and it changes the overall potential of hydrogen production. To give a big picture about the hydrogen production potential of all cities and the reasons behind their capacity, affecting parameters should be considered. Since solar energy has a higher contribution in providing renewable energy, much free space in eastern cities leads to higher energy productions from solar energy. This is normally true from North to the South and from Northwest to Southeast of Turkey. Another deterministic parameter is the available hydroelectric power in different regions. Firat and Dicle Rivers are the main sources of hydropower and it can be seen that neighboring cities to these rivers have a rather higher renewable energy potential and thereby, higher hydrogen production capacity. Figure 3 shows that cities between Manisa and Afyon are beneficial from the local geothermal energy sources. Regarding Black Sea region, it can be seen that despite lower solar radiation, its access to off-shore energy and more hydropower boost this region in terms of hydrogen production potential. In Figure 3, the hydrogen equivalent of annual electric consumption is used in calculations. After deduction of the equivalent hydrogen from the values presented in Figure 2, a new map is created for comparison. Metropolitan cities such as Istanbul, Ankara, Bursa, and Adana lose some of their potential renewable energy due to their high population. İstanbul loses the most because of its highest population, huge energy consumption and lower useful area to be used for energy production from solar, wind, and other forms of renewable energies. There are various parameters that determine the hydrogen production potential of cities. The results show that in regions with a lower population density, and vast useful areas, the renewable energy outputs and consequently, the hydrogen production amount is more than its requirement. Figure 4 illustrates the top 10 cities in Turkey for the hydrogen production. The available power also depends on their access to coastlines and thereafter, the wave, undersea, and offshore renewable technologies. It is of great importance to consider the feasibility of using each technology in all cities. The economic aspects have not been considered in this study, but conducting a parametric study reveals that solar and wind energies are more effective than geothermal and biomass resources in most of the cities. The results also depict that for onshore locations, solar energy is more prevalent than wind energy, but for offshore regions, wind energy potential is bigger than solar energy. Once the wind farms with an average diameter of 90 m (widely used turbines) are considered, the useful areas among them are covered with floating bifacial solar energy which can be considered with a 4% higher efficiency than conventional ones. The top 10 cities can be classified as tier one and tier two cities. Four cities including Erzurum, Van, Konya, and Sivas have the highest surplus renewable energy and therefore, the highest potential for hydrogen production. Erzurum has vast unoccupied land that makes it ideal for solar panels or other types of solar energy technologies. As a matter of fact, the application of solar collectors in these regions are among the highest in Turkey, which shows the solar potential of Erzurum. Also, a less-populated city is another advantage for higher hydrogen production. The cold weather causes a smaller living area and therefore, there is less need for distributed energy system for heating and industrial applications. This population profile and concentrated inhabitant zones make the available lands more suitable for energy harvesting. The second city, Van, has been assumed to be beneficial from the Van Lake, the biggest lake of the country, which despite having a smaller area, makes it a good potential zone for renewable energy production. Konya is more populated than the previous two cities, but its vast free lands and a very high solar energy insolation put this city among the top cities. Sivas takes the fourth spot on the list. Large empty areas and low population density leave a huge amount of area to work with. Tier two cities in Figure 4, with a high hydrogen production potential, have more or less the above-mentioned affecting parameters. Ankara, with vast agriculture and free lands, similar to Konya, has a good renewable energy potential. Another city in tier two group is Antalya that has access to coastlines and can be beneficial from offshore technologies in providing extra renewable energy. Undersea turbines and installation of wind farms in offshore areas that has floating solar panels, which make this city more suitable for the hydrogen hub concept. Limited fossil fuel potentials from one side and ever-increasing stringent policies to decrease the greenhouse gasses through using renewable energy systems from the other side, persuade the policymakers and investors in energy sectors to create a reliable energy hub to tackle these issues. Hydrogen farm concept has the potential to be considered as an applicable platform to gather all renewable energies under one umbrella for many countries. Turkey, with very limited fossil fuel resources and a high potential for renewable energies, is considered a viable candidate for this purpose. The right time to invest in renewable energy resources, integrated with hydrogen hub concept to tackle the storage problems, are among the deterministic steps for a sustainable future, especially in developing countries. Without enough effort, countries like Turkey can miss the boat to have a brighter energy future based on the alternative fuels and green hydrogen. Therefore, the high potential of country can be exploited to ignite the sparks of creating a robust platform for this transition and the results of the current study predicts such a high potential for Turkey. The result of the current perspective study reveals that creating a hydrogen hub in Turkey has the potential to compensate for the total energy consumption of the country. Furthermore, the extra hydrogen production can improve the countries economy and can motivate the countries economy. The feasibility study reveals that produced zero-carbon energy carrier hydrogen from renewable energy sources can support the national objectives for sustainable energy policies and bring it to the attention of governments in declining the dependency on imported energy from other countries. This, in turn, leads to a more robust political role of the country and making it a leading nation in absorbing energy market investments. In order to achieve these goals, a reasonable roadmap is required for the assessment of hydrogen value chain risks and a safer production, storage and distribution system for the green hydrogen.