Construct a detailed, essay-format response to the following prompts, synthesizing all relevant information from the source material.

1. Compare and contrast the challenges, process designs, and economic considerations of desulfurizing atmospheric/vacuum residuals versus lighter gas oils. Use specific processes like H-Oil, RCD Isomax, and GO-Fining as examples in your analysis.
2. Discuss the global and national context of fossil fuel consumption and reserves as presented in the source for the 1980s and beyond. How did these statistics, combined with increasing energy demands and environmental regulations, create a “delicate balance” for the chemical and power industries?
3. Analyze the different approaches to coal desulfurization mentioned in the text, from physical cleaning to chemical processing like the Solvent Refined Coal (SRC) process. Evaluate the effectiveness, limitations, and potential of each method based on the data provided.
4. Explain the fundamental chemical reactions involved in hydrodesulfurization. Discuss the role of catalysts, such as cobalt molybdate, and the process conditions (temperature, pressure, hydrogen) required, as well as the factors that can poison a catalyst.
5. Trace the complete journey of crude oil through a refinery as depicted in Figure 1. Explain how different fractions are separated and processed, and detail where and why desulfurization units like hydrotreaters and Isomax reactors are integrated into the overall flowsheet to produce final products like gasoline and low-sulfur fuel oil.