Bitcoin miners need energy in the form of electricity. In the game, you have two energy sources at your choice. The renewable energy sources and the non-renewable, i.e. fossil, energy sources (coal, but also others such as oil or natural gas). In the game, it is much more lucrative for you to use a renewable energy source than a non-renewable one. For real miners, this is often the case, because renewable energy is in many cases cheaper than fossil energy. In addition, "surplus" energy mainly comes from renewable energy sources. This is the case, for example, with hydroelectric power plants in the rainy season, wind power plants with strong winds or solar power plants with strong sunlight. This is fantastic for a Bitcoin miner, because he is independent of location and can place his mining equipment wherever the energy is cheap. Because Bitcoin mining is location-independent, it can help monetise undeveloped renewable energy sources and can therefore be a driver in the adoption of sustainable energy.
English 
German