Hydrogen has surfaced as critical enabler for deep decarbonization, a zero-emission energy carrier that can be employed in sectors difficult to electrify directly (heavy industry, long-haul transport, seasonal energy storage). The hydrogen economy includes producing hydrogen (for example, through electrolysis and steam methane reforming with carbon capture), storage (compressed gas, liquid hydrogen, salt caverns), distributing (pipelines, tube trailers), and end-use applications (power generation, industrial feedstock and transport fuel). The section does an overview of the literature on hydrogen economy and positions the comprehensive hydrogen analysis of this dissertation (12 GW electrolyzers, 0.8 Mt H₂/year by 2050) within international hydrogen transition pathways.
Green Hydrogen Production Technologies
Electrolysis technologies convert electricity and water into hydrogen and oxygen. There are three main types of electrolysis, namely, alkaline electrolysis or AEC, proton exchange membrane or PEM, and solid oxide electrolysis or SOEC. The AEC technology is the most mature and is assumed to operate at 60-80% efficiency. The capital costs €600-800/kW in 2024. PEM electrolyzers have faster responses which make them suitable for some intermittent types of renewables and over 70-85% efficiency. However, their cost does range from €800-1,200/kW, which is higher. SOEC has the highest efficiency (85-90%) but needs high temperature at (700-900°C) so applications get limited to industrial co-location. Recent developments during 2023 to 2024 are anion exchange membrane (AEM) electrolyzers that have the cost advantages of the alkaline electrolyzer cell (AEC) and the flexibility of the proton exchange membrane (PEM). High-temperature electrolysis requires 20-30% less electricity [iea2024outlook].
Trajectories for reducing costs: Electrolyzer cost (in terms of money) has fallen by 40% since 2020 from $1320.00 (USD 2023)/kW to$770.00 (USD 2023)/kW (2024) due to manufacturing scale-up and technical improvements. According to [irena2024statistics], the costs of these projects will amount to between €300-500/kW by 2030 and €200-400/kW by 2050, assuming that there will be cumulative deployment of 1,000 GW globally. The Learning rates for electrolysers (15-20% per doubling) are comparable to those of solar PV (23%) and wind (14%), an indication that they could see rapid cost reductions as they scale [iea2024hydrogen].
Renewable electricity requirements: Green hydrogen production needs a lot of renewable electricity. To make one kilogram of H₂ through electrolysis, 50-55 kWh electricity required (assuming 70% efficiency). To achieve Turkey's 0.8 Mt H₂/year target for 2050, about 40-44 TWh/year of electricity input will be needed. This will be 6-7% of the projected generation in 2050, which is about 650 TWh. This highlights the importance of renewable surplus and curtailment utilization: using curtailed renewable electricity (zero marginal cost) reduces hydrogen LCOE from $4.95 (USD 2023)/kg to$2.75 (USD 2023)/kg [iea2024hydrogen].
Hydrogen Storage and Distribution
Storage technologies: Hydrogen storage techniques include compressed gas at 350-700 bar with 2-5% energy loss, liquid hydrogen (cryogenic) with 20-30% energy loss, and metal hydrides with 5-10% energy loss (reversible absorption). The least expensive option for large-scale storage is a salt cavern underground, which incurs under 1% energy loss. Salt cavern storage is the least costly seasonal storage at a range of $0.5-1.0/kg (USD 2023). Storage capacity per cavern is around 10,000-100,000 tonnes. Cost of compressed gas is around$2.20-5.50/kg (USD 2023) or equivalent. Turkey's Central Anatolia and Thrace areas have salt formations that can be developed into caverns, with [menr2023strategic] estimating a storage capacity of 500,000-1,000,000 tonnes.
Distribution infrastructure: Hydrogen distribution options consist of repurposed natural gas pipelines that can safely accept hydrogen blends of up to 30% with existing infrastructure and would require material upgrades to accept 100% hydrogen. Another option are dedicated hydrogen pipelines that are new construction and which would cost between $880-1,320 (USD 2023)/meter. Finally, tube trailers mobile distribution which are$13.20 (USD 2023)/kg for 50-100 km. Repurposing a pipeline is 70-80% cheaper than new construction; potential for existing gas infrastructure [iea2024hydrogen].
Hydrogen Demand Sectors
Power sector: Gas turbines that run on hydrogen can provide power without emitting harmful gases. They can also be adjusted to suit renewable energy that works at different times. Current hydrogen-capable turbines run at an efficiency of 30-50%. This efficiency is lower than that for natural gas at 55-60% due to lower energy density. Next-generation designs are targeting 60% efficiency by 2030 as per the IEA (2024) report. Turkey's target of 2.1 GW hydrogen-fired capacity in 2050 will require 23,000 tonnes H₂ per year which means 3% of total hydrogen production.
Industrial sector: Hydrogen is used as a feedstock for steel making (direct reduced iron, DRI), chemical manufacturing (ammonia, methanol), and treatment. The hydrogen-based direct reduced iron (DRI) strategy for steel production requires 50-60 kg H₂ per tonne steel while the present blast furnaces route requires 2-3 tonnes CO₂ per tonne steel. Turkey's steel industry has an annual production of 35 Mt/year. If all decarbonised, the industry could consume 1.75-2.1 Mt H₂/year. This would be higher than the power sector's demand for H₂. The chemical industry (ammonia, methanol) is expected to require 100-150 kg H₂ per tonne product. Turkey's production (5 Mt ammonia, 2 Mt methanol) would require around 0.7-1.0 Mt H₂ a year.
Transport sector: Hydrogen powered fuel cell vehicles (FCEVs) facilitate zero emission mobility. It is suitable for heavy duty applications where batteries are impractical. Long-haul trucks, buses and trains are some such examples. To adopt FCEVs, use an infrastructure which can cost around €3M per station whose capacity should be around 1,000 kg per day. Turkey's transport sector in IEA (2024) managed to convert to hydrogen 30-50% heavy-duty fleet and the use of 0.2-0.5 Mt H₂/year is projected by 2050.
Global Hydrogen Roadmaps
The IEA Net Zero by 2050 scenario suggests that hydrogen production will rise to 530 Mt/year by 2050, with a bulk (60%) of it expected to come from electrolysis (green hydrogen) and remaining 40% from natural gas with carbon capture (blue hydrogen). According to the International Energy Agency (IEA), in order for the world to reach its net zero goals by 2030, the world will need 3,500 GW electrolyzer capacity, requiring an investment of $1.2 trillion by 2030. (2024 update)
The scenario by IRENA that shows pathways to 1.5°C future is green hydrogen focused. The IRENA green hydrogen sees 80% electrolytic production with total green hydrogen generation of 614 Mt/year by 2050. According to IRENA report, the requirement of renewable power is 21,000 TWh/year which is equivalent to 30% of electricity generated globally.
The EU Hydrogen Strategy [hydrogen2020european] estimates required domestic & imports of hydrogen in years 2030 as 10 Mt/year & 10 Mt/year respectively. This will need 40 GW of electrolyzer capacity. Turkey is close to the EU markets. There is a potential to export hydrogen. According to European Commission [hydrogen2020european], by 2050, an exportable surplus of 300,000-400,000 tonnes/year is estimated.
Turkey-Specific Hydrogen Potential
Opportunities and Challenges to Develop Hydrogen Economy of Turkey.
Turkey is capable of producing green hydrogen at competitive prices, given its plentiful renewable constituents including wind and solar. It could be easy to repurpose the country's extensive natural gas pipeline structure for hydrogen distribution. Because of its strategic geographical position, Turkey will be a serious player for hydrogen export and especially to the EU. Turkey's potential hydrogen production could see support from steel and chemicals industries that will act as a load anchor.
The challenges can be divided into two domestic electrolyser manufacturing and spending costs. The country presently does not manufacture the electrolyzer and it is furnished by global companies. The financing cost is between 8-10 per cent whereas that in the EU is 3-5 per cent making hydrogen LCOE costly. As the hydrogen strategy is announced in 2023, regulatory framework is not very well developed but unable to implement. The current pipeline and storage infrastructure requires massive investments which aren't in place.
The dissertation's hydrogen assessment (Chapter 4, Section 4.3) provides a quantitative roadmap on these issues covering 12 GW electrolyzers, 0.8 Mt H₂/year production, and USD 7.6B investment (USD 2023) for Turkey to become a regional hydrogen hub.