Scientists are working on solar refineries to produce useful compounds from which type of gas?

The focus of the question is on the development of solar refineries, which are innovative facilities aimed at harnessing solar energy to convert gases into useful compounds. Waste gas is the correct answer because it typically contains various components that can be transformed into valuable products through chemical processes. These could include gases emitted from industrial processes that, rather than being released into the atmosphere, can be captured and repurposed.

Using waste gas in solar refineries aligns with sustainability goals, as it addresses environmental concerns by reducing emissions and utilizing byproducts that would otherwise contribute to pollution. The transformation of waste gas into useful compounds can also support the creation of renewable fuels, chemicals, and other materials essential for a circular economy.

While natural gas and greenhouse gas can be part of energy discussions, they do not typically represent the primary focus of emerging technologies aiming to utilize waste gases. Catalytic gas does not represent a specific category relevant to the objectives of solar refineries in the same context, further affirming that waste gas is the best choice in this scenario.