The article discusses different ways to make hydrogen, a key element in the hydrogen economy. It looks at how much it costs to produce hydrogen from sources like natural gas, coal, sunlight, wind, and biomass. The study found that coal and natural gas are the cheapest ways to make hydrogen, costing between 0.36 and 1.83 dollars per kilogram for coal and 2.48 to 3.17 dollars per kilogram for natural gas. While alternative energy sources are more expensive now, they could become cheaper in the future as technology improves.