Enlarging the EU's internal energy market: Why would third countries accept EU rule export?

Why would countries without a membership perspective seek integration into the EU's internal energy market? One major element of the EU's external energy policy is the export of EU energy norms and regulations to neighbourhood countries and beyond. A core legal instrument the EU uses in this context is the Energy Community Treaty (ECT). The ECT goes both geographically and regarding its depth significantly beyond neighbourhood or association policies, addressing potentially also countries in the 'far neighbourhood' and aiming at the creation of a Single Market for energy with these countries. While, however, EU candidate countries are obliged to adopt the "acquis" before accessing the EU and therefore comply to EU rules already before they enter the Club, I argue that countries with no or only a vague membership perspective - i.e. countries where the EU cannot apply the "conditionality" - approach (e.g., ENP countries)--aim at deeper integration with the EU because they are either eager to demonstrate their capability and potential to become part of the Club, they seek greater independence from a regional hegemon or they envisage significant economic gains as common norms, rules and standards are likely to increase economic exchange with the EU.