# Wind Turbine Technology Trends
## 3 Discussion
### Offshore Wind Turbine Development
It could potentially contribute to system flexibility by acting as \"seasonal storage\" to help integrate various renewable energy sources. Hydrogen contributes to the \"sectoral connection\" between the electric power system and industry, construction, and transportation. Due to the existence of an extensive gas infrastructure that can be used to transport hydrogen-natural gas mixtures and also converted to transport pure hydrogen, the EU is well positioned to become a leading region in the global hydrogen economy [63]. In its report [2], IRENA forecasts a 19 exajoule increase in the global economic potential of hydrogen from renewable energy sources in total final energy consumption by 2050. This would represent 5% of total final energy consumption, and 16% of the electricity generated would be used for hydrogen production by 2050. Governments, energy consuming companies (chemical companies, steel producers, etc. ), and end users are increasingly interested in offshore wind as an energy source for the production of green hydrogen (produced by electrolysis from renewable energy sources) that can be used in various sectors of the economy (e.g., transportation, heating, industry, grid storage) as a fuel with zero pollutant emissions. Several early-stage global projects are being planned by Shell, RWE, Equinor, Gasunie, Gascade, Orsted, and Boskalis. These producers plan to install 10 GW of wind power to obtain hydrogen as part of the AquaVentus/AquaDuctus project. Hydrogen can thus play a key role in implementing the EU's offshore renewable energy strategy. The goal is to obtain up to 1 million tons of hydrogen from 2035 [63]. POSCO, as one of the largest South Korean steel producers, plans to use the 1.6 GW Orsted offshore wind farm to produce the hydrogen needed for further steel production. Neptune Energy's PosHydroon project plans to use the produced hydrogen for Dutch utilities Gasunie, Eneco, Noordagstransport and Northern Offshore Gas Transfer. Orsted's H2 RES hydrogen production project will use two 3.6 MW offshore wind turbines at Avedere Holme to obtain one ton of hydrogen per day for \"green\" road transport in the urban area of Copenhagen [5]. Finally, it is worth noting that some research has addressed the analysis and improvement of vertical axis wind turbines, although they are very little used compared to horizontal axis wind turbines. In the work of [PERSON] et al. [64], a modification of Savonius wind turbines is considered. The proposed modification consists of a curtain arrangement with additional fins on the blade. The effect of the proposed modification was predicted by CFD simulation using ANSYS FLUENT software. It was found that the maximum power coefficient of the Savonius rotor with the optimal curtain arrangement (curtain blade lengths 1000 mm and 1150 mm and curtain blade angles 30 and 50) together with the addition of only one fin increased by about 42%. The rotation induced by the flow through a modified Savonius rotor, in which the blade consists of a semicircular profile and an elliptical shape, is studied in the work of [PERSON] et al. [65] using unsteady flow simulations (CFD). The modified rotor provides excellent performance at a tip speed ratio (TSR) of more than 0.8, and the new peak power coefficient Cp is achieved at TSR = 1.4, which is the typical operating condition of wind turbines in urban areas. Thus, their study not only contributes to the basic understanding of the flow mechanism around the rotor, but also suggests a good practical application of this type of rotor for power generation in urban areas. In the work of [PERSON] et al. [66], a new vertical axis wind turbine (VAWT) with side-by-side overlapping Savonius rotors was designed and analyzed. The new VAWT consists of multiple Savonius rotors with a distance between adjacent rotor axes smaller than the rotor diameter. It was found that the new VAWT has an incredible efficiency improvement of 46.95% at TSR = 0.4.