Control over the Persian Gulf was a source of tension heading into World War I, and within a few years it very well could have become a potential cause of World War I as the extent of the petroleum there became clear. All the industrial powers had enough coal to meet domestic demand apart from the Italians (even Japan), but none of the major powers in Europe or Japan had any sizable petroleum reserves apart from Imperial Russia and Austria-Hungary which was the third or fourth largest producer of petroleum in the world before World War I. It seems quite likely that any conflict over petroleum would come from the Entente, not the Central Powers. The Berlin-Baghdad Railway is favorable to the Austro-Germans and Ottomans even without a Kuwait terminus, and the decision to invest in it was made even after Kuwait had fallen into the British sphere of influence under the 1899 Anglo-Kuwaiti Treaty. In fact, without a Kuwait terminus the export of Mesopotamian petroleum through the Persian Gulf becomes greatly complicated, giving the Austro-Germans a competitive advantage in purchasing it. While everyone can compete to purchase Persian petroleum delivered by ship, the Austro-Germans would control the Berlin-Baghdad Railway and with it the supply of Mesopotamian petroleum, meaning France, Italy, and other countries would have an even more difficult time. Imperial Russia could supply its own petroleum needs and Austria-Hungary could to some extents as well, but other countries would be reliant on imports. Imperial Germany could acquire petroleum from Mesopotamia through the Berlin-Baghdad Railway and the British Empire could from Persia, but France and Italy would have no resources at the time (those in Algeria, Libya, and French Africa were not discovered until much later). Because France and Italy would need petroleum and wouldn't be able to source it from within their own empires it could further increase Franco-German and Austro-Italian tensions. Its possible that pipelines might later be built to export petroleum and especially natural gas from the Middle East to Europe. Big Inch and Little Big Inch, the world's first petroleum pipelines, were fairly easily converted to natural gas service shortly after they were built. While natural gas was used for industrial and residential heating and other purposes before the 1970s (not power production) and its possible to use coal to gas processes to produce coal gas (common in the United Kingdom and parts of the United States well through the 1960s), it is not very efficient. By then the time pipelines start being built the energy landscape of Europe could be quite different. While Austria-Hungary and Germany have extensive coal reserves, it could potentially become less expensive for them to use petroleum for both heat and power generation. Although it seems strange now, between the end of World War II and 1973 (arguably even 1979) petroleum was both less expensive and considered more environmentally friendly than coal due to its lower sulfur emissions (petroleum does produce more small particulates that produce smog and health effects though). Petroleum didn't really take off in the United States until the 1963 Clean Air Act, so something similar might be needed to give it a boost in Germany. Germany has a lot of lignite/cheap soft coal too, so that could give coal an advantage, especially if flue gas desulfurization technology enters widespread use earlier (the British used it at Battersea, Swansea, and Fulham in the 1930s but abandoned the technology during World War II). However, cheap petroleum could harm Austro-German economic competitiveness in the long run because there wouldn't be a push for efficiency. With petroleum being such a large part of their economies it could also drive investments away from industry and other sectors towards petroleum and its higher rates of return (an economic phenomena known as Dutch Disease). France might pursue nuclear energy earlier than it did historically if it is shut out of the world petroleum market, as well as Italy. Jean Frederic Joliot-Curie and Irene Joliot-Curie were working on radioisotopes, nuclear fission, reactors, and other areas of nuclear research at the Radium Institute in France prior to World War II. Enrico Fermi could make a major contribution to nuclear technology in Italy.