## 2 Research Method
### Literature Reviews and Key Findings
The Global Hydrogen Review claims that AEME electrolysis combines the benefits of PEME and AKE, since it does not require expensive platinum utilized by PEME nor the corrosive electrolytes used in AKE, but it is a less mature technology [22]. Emerging technologies for clean H\({}_{2}\) production are also evaluated in this research. Because of the novelty of these technologies, they will not have very high TRLs, with most still being in the research and early development stages [16; 22; 39]. Several studies of thermochemical decomposition via both solar and nuclear power demonstrate that these technologies are far from being commercially mature [9; 34]. However, even though the technologies are immature, their TEA reveals that several of the emerging technologies, like bio-photolysis, biomethane pyrolysis, and ESMR, are potentially able to produce H\({}_{2}\) for competitive prices [11; 28; 40; 41]. ESMR is especially attractive when considered as an easily implemented technology to help aid in the transition from gray to cleaner H\({}_{2}\). It utilizes the same natural gas feedstock but incorporates renewable electricity to lower emissions, resulting in a system that is more sustainable than the conventional methods and more economically and technically feasible than the other emerging technologies [41]. Among the emerging H\({}_{2}\) production technologies is the so-called white color, of natural origin; however, due to its rare occurrence in the Earth's rock, there is no commercial interest at this point in time [42]. This geologic H\({}_{2}\) (aka., white, gold, or natural H\({}_{2}\)) is found beneath the Earth's surface and is postulated to be produced by high-temperature reactions between water and iron-rich minerals. Most of the other emerging technologies still require more technological development to compete with standard hydrogen prices [24; 43]. Strategic plant optimization can help lower production costs. For example, H\({}_{2}\) costs from ammonia thermal decomposition via fixed-bed reactors and PSA membranes are expected to decrease if plants are built to be larger and centralized, which would lead to economies of scale and less expensive ammonia costs [44; 45]. One article discussed how the fluctuations in H\({}_{2}\) production costs via thermochemical processes are mainly due to variable electricity prices, but the utilization of reliable green electricity from renewable sources like solar PV and wind turbines can greatly reduce production costs [11]. The lack of comprehensive studies of promising emerging technology, like biomethane pyrolysis and SMC, has been called out and discussed. These turquoise H\({}_{2}\) production technologies [46] are preferable to SMR due to their lower emissions and energy requirements, but the information on them is still sparse and the data are often conflicting and inconsistent [47]. There tends to be a disproportionate focus on green H\({}_{2}\) production technologies, particularly water electrolysis,despite other promising candidates. Further analysis of these emerging technologies will open up a slew of diverse avenues for clean hydrogen production. Another reason to invest more resources in a wider range of promising clean H\({}_{2}\) production technologies is their potential to be combined and integrated into hybrid systems. This integration process can strategically lower H\({}_{2}\) production cost, decrease energy requirements and carbon emissions, increase efficiency, and utilize waste to make useful products. A well-established example of technology integration is the addition of CCS to gray H\({}_{2}\) production technology, a method that succeeds in reducing emissions but also tends to increase production cost and energy consumption while reducing process efficiency [7; 8; 10; 17; 47]. More technically advanced and economically and energetically efficient combinations can be devised. One paper performed an energy analysis of an integrated system with SMC and SOE for the production of turquoise H\({}_{2}\) and clean methanol [38].