Preparations started in 2002 and the intergovernmental agreement between Turkey, Romania, Bulgaria, Hungary and Austria was signed on 13 July 2009.

After an announcement of the construction of TANAP, the consortium submitted the Nabucco-West project, which was to run from the Turkish-Bulgarian border to Austria.

[10][11][12] An objective of the project is to connect the European Union better to the natural gas sources in the Caspian Sea and the Middle East regions.

[13][14][15] The project has been driven by the intention to diversify its current energy supplies, and to lessen European dependence on Russian energy—the biggest supplier of gas to Europe.

Simon Pirani, senior research fellow, Oxford Institute for Energy Studies presented to delegates at the Ukrainian Energy Forum in 2013 a list of prices from the Russian newspaper Izvestia: "What they show is the prices at which Russian gas is being purchased in different European countries, and this tells quite a simple story.

"[20] Preparations for the Nabucco project started in February 2002 when first talks took place between Austrian OMV and Turkish BOTAŞ.

In June 2002, five companies (OMV of Austria, MOL Group of Hungary, Bulgargaz of Bulgaria, Transgaz of Romania and BOTAŞ of Turkey) signed a protocol of intention to construct the Nabucco pipeline.

The name Nabucco comes from the same famous opera of Giuseppe Verdi, which was given to the project in the very early phases by Lutfu Atasoy (a consultant to Erdemir Engineering Company in connection with BOTAŞ) in a request for inquiry for pipeline engineering services to Kent plc.

Atasoy wanted to shorten the original verbose project name, and decided to suggest Nabucco, which he had been listening to throughout his car ride on the way to the meeting with the General Manager of Erdemir Engineering Company at the time.

[31] The intergovernmental agreement between Turkey, Romania, Bulgaria, Hungary and Austria was signed by five prime ministers on 13 July 2009 in Ankara.

[32] The European Union was represented at the ceremony by the President Jose Manuel Barroso and the Commissioner for Energy Andris Piebalgs, and the United States was represented by Special Envoy for Eurasian Energy Richard Morningstar and Ranking Member of the United States Senate Committee on Foreign Relations Senator Richard Lugar.

[44] The original 3,893 kilometres (2,419 mi) long pipeline was to run from Ahiboz in Turkey via Bulgaria, Romania, and Hungary to Baumgarten an der March, a major natural gas hub in Austria.

The total length of Nabucco West is 1,329 kilometres (826 mi), with the following distances in each of the below countries:[45] From Turkey, the original Nabucco pipeline was proposed to enter Bulgaria and after running 76 kilometres (47 mi) in parallel to the existing gas system connect to the Bulgarian national gas network at the compressor station of village Lozenets in Yambol Province.

The pipe would follow the south western border of Romania and will travel through the counties of Dolj, Mehedinți, Caraș-Severin, Timiș, and Arad.

The pipeline would cross 11 protected sites, two national parks, three natural reserves, and 57 watercourses, namely major rivers such as: Jiu, Coșuștea, Cerna, Belareca, Timiș, Bega, and Mureș, as well as their tributaries.

The front end engineering and design (FEED) services of the pipeline, including the overall management of the local FEED contractors, the review of the technical feasibility study, route confirmation, preparation of the design basis, hydraulic studies, overall SCADA and telecommunications, GIS and preparation of tender packages for the next phase, was managed by UK-based consultancy Penspen.

[29] On 5 February 2010, the EIB vice-president Mathias Kollatz-Ahnensaid that Nabucco consortium was seeking up to €2 billion (20–25% of costs) in bank financing.

[72] Prime Minister of Turkey Recep Tayyip Erdoğan has urged Egypt to export natural gas to Europe via the Nabucco pipeline.

[73] Iran has also proposed to supply gas to Nabucco pipeline and this was backed by Turkey; however, due to the political conditions this is rejected by the EU and the United States.

[7][8][74][75] Nabucco-West is designated to carry Azeri gas from the second stage of Shah Deniz through TANAP pipeline.

[citation needed] Azerbaijan, Georgia, Romania and Hungary are developing Azerbaijan–Georgia–Romania Interconnector project, which is proposed to transport Azerbaijani gas to Europe in form of LNG.

[89] Increasing availability of LNG from large gas-producing countries in the Middle-East and Africa stresses the economic viability of pipelines.

[93] This is supported by Russia's gas deals with Azerbaijan and Turkmenistan, which by some observers has been seen as attempt to reserve potential Nabucco supplies.

NGOs have also criticized the fact that the pipeline results in effective support of the authoritarian regime in Turkmenistan, which undermines the European Union's policy of human rights promotion.

[97] Some NGOs criticize the EIB and EBRD for their willingness to finance a fossil fuel project, claiming that it goes against the November 2007 resolution on trade and climate change passed in the European Union Parliament.

"[99] Non-governmental organizations also show disapproval, due to the public banks decision to be lenient to Turkmenistan Human and civil rights conditions.

Gas for the Nabucco pipeline coming from Azerbaijan and Turkmenistan will have to pass near areas of instability in the South Caucasus.

Moscow was able to safeguard its dominant market share in Central and Eastern Europe and then pressured most of these countries to support Gazprom’s South Stream pipeline, a rival to Nabucco.

Nabucco pipeline lacked the necessary political and diplomatic support from both the EU and the United States to overcome pressures from Russia and Gazprom.