been filtered through a lime-based chemical absorbent. The submarine could also run its diesel using a snorkel. The Quebec had three drive shafts: a 32D diesel on the centre shaft and two M-50P diesels on the outer shafts. In addition a "creep" motor was coupled to the centre shaft. The boat could be run at slow speed using the centreline diesel only. Because liquid oxygen cannot be stored indefinitely, these boats could not operate far from a base. It was dangerous; at least seven submarines suffered explosions, and one of these, , sank following an explosion and fire. They were sometimes nicknamed cigarette lighters. The last submarine using this technology was scrapped in the early 1970s. The German Navy's former Type 205 submarine (launched 1967) was fitted with an experimental unit. Closed-cycle steam turbines The French MESMA (Module d'Energie Sous-Marin Autonome) system is offered by French shipyard DCNS. MESMA is available for the Agosta 90B and s. It is essentially a modified version of their nuclear propulsion system with heat generated by ethanol and oxygen. Specifically, a conventional steam turbine power plant is powered by steam generated from the combustion of ethanol and stored oxygen at a pressure of 60 atmospheres. This pressure-firing allows exhaust carbon dioxide to be expelled overboard at any depth without an exhaust compressor. Each MESMA system costs around $50–60 million. As installed on the Scorpènes, it requires adding an , 305-tonne hull section to the submarine, and results in a submarine able to operate for greater than 21 days underwater, depending on variables such as speed. On the Agosta 90B, the AIP system allows the submarine to operate 16 days under water and gives it a range of . An article in Undersea Warfare Magazine notes that: "although MESMA can provide higher output power than the other alternatives, its inherent efficiency is the lowest of the four AIP candidates, and its rate of oxygen consumption is correspondingly higher." Stirling cycle engines The Swedish shipbuilder Kockums constructed three s for the Swedish Navy that are fitted with an auxiliary Stirling engine that burns diesel fuel with liquid oxygen to drive 75 kW electrical generators for either propulsion or charging batteries. The underwater endurance of the 1,500-tonne boats is around 14 days at , with an approximate range of 1700 nautical miles. Kockums refurbished and upgraded the Swedish submarines with a Stirling AIP plugin section. Two (Södermanland