Compressing biogas into an LPG cylinder typically requires a biogas compressor and a storage tank. The biogas compressor is used to increase the pressure of the biogas, allowing it to be stored in the LPG cylinder. Additionally, the storage tank is used to hold the compressed biogas until it is ready to be transferred to the LPG cylinder. If you are unsure of how to properly compress biogas, you may want to consult a professional for assistance.