What is the fine-grained topic of the following text: As stated on the website of the Ev-K2-CNR Association, the Pyramid is a one-of-a-kind resource, also with regard to energy efficiency, which is the aspect most relevant to our main activity: the laboratory is self-sufficient and is powered by a hybrid system consisting of a small hydroelectric power plant and a solar panel system. Only return the topic.
Energy Efficiency of the Ev-K2-CNR Pyramid Laboratory