ABSTRACT: This paper analyzes the retrofitting of a conventional, “gray” ammonia plant for its partial decarbonization. Specifically, the retrofitting involves the hybridization of the process by providing a certain amount of green hydrogen (i.e. by water electrolysis) for the ammonia synthesis to reduce the demand for the original gray hydrogen route (i.e. by fossil-based steam reforming) and consequently reduce CO₂ emissions. As such green hydrogen is produced through an electrolyzer that consumes renewable electric energy, two design configurations are considered: (Option I) the supply of clean electricity from renewable sources; (Option II) the generation of clean electricity by an in-house photovoltaic power plant. Once having analyzed the advantages and limitations of the hybrid plant layouts, the ammonia production costs achieved by the three simulated plants (i.e. the reference “gray” plant and the two hybrid alternatives) are estimated by considering the United States (USA) and European Union (EU) market quotations in 2022 and previsions for 2030 and 2050. The main outcomes are that (i) hybrid-green ammonia proves to be a feasible, environmentally friendly retrofitting option for the ammonia production industry, showing production costs that are no more than 36% higher than gray ammonia; and (ii) Option I achieves better cost-effectiveness than Option II in the USA, while the opposite happens in the EU. Specifically, the resulting 10%-green-on-average hybrid-green ammonia production costs range between +0.3% (EU-2022) and +30.8% (USA-2022) for Option I, and between −1.3% (EU-2022) and +35.3% (USA-2022) for Option II, compared to the reference gray ammonia plant. (iii) Lastly, the projected (i.e. in 2030 and 2050) CO₂ avoidance costs associated with hybrid-green ammonia configurations exceed 400 USD/t_CO2 in the USA and 500 USD/t_CO2 in the EU.

DOI: 10.1016/j.cej.2024.150132

ABSTRACT: Recent years have seen a growing interest in studying new methods to predict the correct dose of levothyroxine (LT4) that is used as a synthetic drug for hypothyroidism treatment and supplements/substitutes the T4 hormone secreted by the healthy thyroid. The paper proposes a quantitative procedure for the optimal administration of LT4 through a model-based approach dependent on some individualized parameters of the patient to free the endocrinologist from the current rough guesses of LT4 dosage. A dedicated algorithm receives as input data the patient features along with the major indicator of thyroid status, i.e. the serum concentration of TSH, the thyroid-stimulating hormone. Then the procedure calculates the Residual Thyroid Function (RTF), which quantifies the thyroid efficiency status, and eventually the optimal LT4 dose. As a complement to the quantitative models available in the scientific literature, we also take into account the age of the patient to determine the optimal dose that can avoid any suboptimal prescriptions regarding hypothyroidism diagnosis for both young and elderly individuals.

DOI: 10.1016/B978-0-443-15274-0.50420-0

ABSTRACT: Ammonia is one of the leading products of the chemical industry worldwide. In addition, its manufacturing is significantly both energy- and emissions-intensive. As ammonia production is heavily based on fossil fuels, its synthesis integration with the Allam power cycle is a promising technology that can lead to substantial decarbonization of the whole process and an important abatement of the electrical energy costs (and indirect emissions). The Allam cycle is a system for high-efficiency power generation with supercritical CO2 working fluid. Its integration into conventional ammonia plants allows for simultaneously producing electricity, water, and pipeline-ready carbon dioxide. An original, improved layout of a gray ammonia plant combined with the Allam power cycle is simulated to run a techno-economic assessment of the process and detect the optimal operating conditions that improve its economic and environmental sustainability.

DOI: 10.1016/B978-0-443-15274-0.50405-4

ABSTRACT: Ammonia synthesis is the biggest emitter of carbon dioxide among chemical processes. Emission regulations will become even stricter over the coming decades and call for innovative sustainable pathways to meet the decarbonization targets. An answer to such a transition may be retrofitting (i.e. hybridization) the existing plants by implementing low- or zero-emission technologies. One of the most promising retrofits is introducing green hydrogen from electrolyzers into the synthesis loop. This paper compares the operational expenditures (OPEX) of a conventional gray ammonia plant and a 10%-decarbonized electrolysis-based hybrid-green ammonia plant. The OPEX terms depend primarily on natural gas costs, renewable electric energy prices, and carbon tax values. Specifically, hybrid-green ammonia proves to be competitive at current EU natural gas quotations, which have increased more than five-fold since the first semester of 2021 due to the ongoing Russia-Ukraine war.

DOI: 10.1016/B978-0-443-15274-0.50364-4

ABSTRACT: Global warming is becoming an increasing issue, and greenhouse gas (GHG) emissions represent the engine of such a phenomenon. This review aims to identify the origin of GHG emissions and focus in detail on the ones related to (petro)chemical industries. The industrial sector is the primary GHG emitter among all the other anthropogenic sources. The chemical industry is the first in charge of that (having accounted for about 6.5% of the global GHG emissions in 2018). Thought-provoking data such as yearly productivities and emission factors related to the predominant chemicals prompt the reader to acquire a sense of the critical activities responsible for carbon-intensive emissions, which should be the first to be decarbonized. Specifically, ammonia synthesis and steam cracking resulted in the most polluting processes of the chemical industry, being responsible for the release of about 440 and 228 Mt-CO2,eq/y, respectively, in 2020. The same approach also applies to oil refining. Due to the massive amounts of oil barrels produced daily, oil refining is a key player in industrial GHG emissions (about 3% of the global emissions in 2018). Indeed, in 2020, refineries emitted nearly 1313 Mt-CO2,eq/y.

LINK: https://www.mdpi.com/1996-1073/15/20/7560