Adrian Videanu, Romania's economy minister, officially launched his country's bid to host the European agency at a public event in Brussels.
The agency's establishment is part of the European Commission's ambition to further liberalise EU energy markets and streamline cross-border cooperation for gas and electricity transmission between member states.
The minister underlined what he presented as the many advantages of the Romanian offer, including a five-year rent-free period.
Slovenia and Slovakia had already presented their bids, which included two-year rent-free periods.
To further sweeten its bid, Romania also offered diplomatic immunity to all ACER staff, including VAT exemptions for goods and services, while Ljubljana and Bratislava provided for similar privileges only for its high management.
A decision on where to host the agency could be taken as early as 18-19 June, when EU leaders will meet in Brussels to decide on the next Commission president after the European elections.
Bucharest has various other attractions, the minister added, including a "vibrant nightlife", "tasty food" and "excellent wines".
He said Romania could also build on its geographical position at the EU's eastern border by promoting European initiatives in the neighbourhood.
But the geographical argument has also been used by Slovenia. Speaking to EurActiv, Mary Veronica Tovšak Pleterski, a high-ranking diplomat from the Slovenian Permanent Representation to the EU, also highlighted her country's role, during its EU presidency in the second half of 2008, in achieving consensus on the energy liberalisation package.
Asked if her country was afraid of being penalised for blocking Croatia's EU accession talks, Tovšak Pleterski ruled out such a possibility and expressed her strong belief that her country would be selected.
As for Slovakia, the country is hoping to benefit from its well-developed power sector. Slovakian Economy Minister Ľubomír Jahnátek, who was also in Brussels recently to launch his country's candidacy, was quoted as saying that his country has more experience in power-sector regulation than its competitors.