02. Intro and overview

Power-to-X converts renewable electricity, from wind, solar, hydro, and geothermal power plants, into a wide variety of end products (X) such as heat, gas or liquid fuels.

PtX is crucial for decarbonization for several reasons:

1. Sector coupling: PtX allows the transfer of renewable energy into sectors that are hard to electrify, such as industry, heavy transportation and aviation.

2. Long-term storage: PtX provides a solution for long-term storage of renewable energy. Batteries can only store energy for short periods, whereas synthetic gases and liquid fuels (products of PtX) can be stored over long periods.

3. Reduction of greenhouse gases: PtX technologies can be designed to capture and use CO2, thus directly reducing greenhouse gas emissions.

4. Energy transportation: PtX facilitates transport of energy from regions with abundant renewable energy resources to regions that lack them, by converting electricity to a transportable form.

1. Efficiency: The process of producing synthetic fuels is less efficient compared to using electricity to charge electric vehicles (EVs). Creating hydrogen through electrolysis, converting it into a synthetic fuel, and then using it in an internal combustion engine involves multiple stages, each of which suffers from energy loss. In contrast, electric vehicles charge and discharge electricity directly in a relatively simple and efficient process. 2. Cost: Currently, the production of hydrogen and subsequent conversion into synthetic fuels is more expensive than conventional fuels and other alternative technologies, like battery electric vehicles.

Blue hydrogen is produced from natural gas through a method called steam methane reformation (SMR), which separates hydrogen atoms from natural gas. The carbon emissions produced in this process are captured and stored underground instead of being released into the atmosphere. This capture and storage of CO2 is what differentiates "blue" hydrogen from "grey" hydrogen, which is also produced from natural gas but without any capture of CO2 emissions.

However, it should be noted that blue hydrogen is not totally carbon-free. The carbon capture, use, and storage (CCUS) strategies associated with blue hydrogen usually capture about 85 90% of the emitted CO2, not 100%, so there are still some carbon emissions associated with this process.

CO2 and fugitive CH4 emissions for blue H2 can be higher than those from natural gas! à Blue H2 is only 10% better than grey H2! CH4 emissions from gas leakage must

1. Proton Exchange Membrane (PEM) Electrolyser: - Advantage: PEM electrolysers can operate at higher current densities, which means they can ramp up quickly to capitalize on surplus electricity from renewable sources. This makes them ideal for applications that require quick response times. - Disadvantage: However, PEM electrolysers are generally costlier because of their use of expensive catalyst materials, such as platinum and iridium.

2. Alkaline Electrolyser: - Advantage: Alkaline electrolysers have been around for a long time and are widely considered as mature technology. They are less expensive than PEM electrolysers, mainly because they use cheaper materials. - Disadvantage: Alkaline electrolysers operate less flexibly with regard to electricity input variations. This makes them less suited for operations with fluctuating power inputs, such as electricity from wind or solar power.

3. Solid Oxide Electrolyser Cell (SOEC): - Advantage: SOECs run at high temperatures (between 500–1,000°C), which can improve the conversion efficiency. This means that they can produce hydrogen more efficiently than other types. - Disadvantage: The high-temperature requirement leads to a longer start-up time and higher thermal stress on the system, possibly affecting the lifetime of the electrolyser. Furthermore, the technology is less mature and still under development compared to PEM and alkaline.

In the context of Power-to-X (PtX), sustainable carbon typically refers to carbon dioxide (CO2) that has been captured from sources which don't contribute to the increase of overall levels of atmospheric CO2. This sustainable or "recycled" carbon dioxide would then be used as a reactant in the production of synthetic fuels or other chemicals. There are a few potential sources for sustainable carbon:

1. Direct Air Capture: CO2 is captured directly from the atmosphere through engineered chemical reactions.

2. Industrial Emissions: CO2 is captured from emissions of industrial processes, such as steel-making or cement production. This process not only recycles CO2 but also reduces industrial carbon emissions.

3. Biomass: CO2 can also come from biomass, such as plant-based material or organic waste.

1. Haber-Bosch Process: The final product of the Haber-Bosch process is ammonia (NH3). This process combines nitrogen (N2) from the atmosphere with hydrogen (H2) under high temperature and pressure in the presence of a catalyst (usually iron) to synthesize ammonia. This is a key process in the manufacture of fertilizers, as ammonia is a building block for nitrogen-based fertilizers.

2. Sabatier Process: The final product of the Sabatier process is methane (CH4) and water (H2O). In the Sabatier process, carbon dioxide (CO2) is reacted with hydrogen (H2) over a nickel catalyst. The resulting reaction produces methane and water. This process is of interest for potential use in waste carbon dioxide and hydrogen from electrolysis conversion to generate methane fuel, a principle component of natural gas.

1. Cost of Electricity: Green hydrogen is produced by using renewable energy to power the electrolysis of water. The cost of this electricity, particularly from renewable sources like solar or wind energy, is usually the largest factor in the cost of green hydrogen production. 2. Electrolyser Capital and Operational Costs: This includes the cost of the equipment (like the electrolyser unit and other peripherals), as well as installation, operational, and maintenance costs. It also includes the cost of replacing components over the lifetime of the electrolyser. More advanced or efficient electrolyser technologies (like PEM electrolysers) are usually more expensive.

1. High Availability of Renewable Energy: regions with high levels of sun and/or wind exposure are ideal for producing green hydrogen. This includes places like the desert regions of the Middle East and North Africa for solar power, or coastal areas for wind power. Places with stable, robust and high renewable energy generation will have the lowest energy costs.

2. Access to Large Amounts of Fresh Water: Electrolysis requires a significant amount of water. The ideal location for a green hydrogen production facility would therefore have plentiful access to water. It is also possible to use desalinated seawater, although this would involve additional costs.

3. Proximity to Consumption or Export Sites: Transportation and storage of hydrogen can be challenging and costly, so regions near major hydrogen consumers (like industrial clusters) or with access to well-established transport networks (rail, road or ports for export) would be at an advantage.

4. Space Availability: Electrolysis plants, solar panels, and wind farms all require significant space. Thus, regions with ample available land would be ideal.

5. Stable Regulatory and Economic Environment: While not a geographic condition, this is crucial for large scale and long-term investments.

1. Stable and Friendly Trade Relations: The relationship between the producing country and Germany is a critical factor.

2. Infrastructure for transport: Hydrogen is challenging to transport. It requires specific infrastructure, such as pipelines optimized for hydrogen, or conversion into other substances for transport and reconversion at the destination, both processes adding to the cost.

3. Import Costs: Import costs, including tariffs, shipping costs, insurance and other fees, play a crucial in the economic viability of importing green hydrogen.

4. Supply Reliability: The dependability and consistency of the green hydrogen supply from the producing country is critical, especially for a resource as crucial as energy.

The different colored lines represent different electricity prices per MWh. The vertical axis the cost of H2 in $/kg of H2 and the horizontal axis the FLH. The CAPEX is in all cases the same, so from this graph we can interpret that the longer the electrolyzer is used, the less impact has the CAPEX in the H2 price. With high FLH we see that the price of electricity makes most of the difference in the H2 price, this happens because the price of electricity does not decrease with higher consumption, it is always the same per MWh, but the CAPEX divides among more Kgs of H2, making the impact per Kg lower.