A study by Energy and Environmental Research Associates for T&E, "How Much LNG Discharges Before Burning on a Ship?", suggests that LNG imports into Europe cause 30 % more pollution than the EU originally estimated in its plans for green shipping. Although oil and gas companies often promote LNG as a "reliable and clean" alternative that is significantly more sustainable compared to heavy fuel oil, one of the world's most polluting fuels, the study suggests that this may not be entirely accurate. There are currently nearly 1,200 LNG-powered ships in operation worldwide, with shipping companies on order for another nearly 1,000. T&E also previously estimated that up to a quarter of EU shipping could be LNG-powered by 2030. (More at "How much LNG will it release before burning on the ship?)