The fundamental practice to awaken the Lower Dantian is reverse abdominal breathing. This should be done in a special hand posture to seal the energy in the Lower Dantian. This is taught to all students of taoistalchemy.org.
This practice of reverse abdominal breathing will slowly start to fill the Lower Dantian with Yang energy. If you are seated on the earth or ground floor yin energy will also be accumulated however it won’t be stored in the Dantian but the huiyin (perineum).
It is only after an adequate amount of yin and yang energy is build up can one attempt to bring the two energies together and establish the elixir pill.
The fusion of yin and yang creates the elixir pill.
After this point one may begin igniting the Lower Dantian. This process is very secretive and it was closely guarded in the past.
Most qigong schools only reach the point of filling the Lower Dantian with yang energy. Most do not have the methods to establish the elixir pill and ignite the Lower Dantian.
From this point a tangible electrical current becomes developed in the body.
Some have named this kind of tradition Leishandao (School of Thunder and Lightning.)