Concentrates in the context of energy commodities typically refer to a form of substance which has been processed to increase its purity and potential energy content. This is usually done by removing extraneous materials, resulting in a product that is denser in energy-creating compounds. In the energy sector, concentrates may pertain to substances like metallurgical coal, which is used in steel-making processes, uranium concentrates (yellowcake) used in the nuclear energy industry, or even more refined forms of natural resources like concentrated solar power.

The process of concentrating a raw material can involve a variety of methods such as crushing, grinding, or the application of heat and chemical treatments. The goal is to strip away impurities and retain as much of the primary energy-producing element as possible. As a result, the energy output per unit weight increases, making the concentrate more efficient for transportation and use in energy generation.

Here are two sources where you can find more information about concentrates and their use in the energy commodities sector:

1. U.S. Energy Information Administration (EIA)
The EIA provides comprehensive data, forecasts, and analyses of energy commodities, including information on different types of concentrates and their applications within the energy sector.
https://www.eia.gov/

2. Investing News Network
The Investing News Network offers financial and investing news with a particular emphasis on commodity markets, giving insights into how concentrates play a role in the commodities trading arena, including the market dynamics and investment opportunities.
https://investingnews.com/

Please ensure that you verify these resources and that they are appropriate for your needs as offerings on third-party websites may change over time.