Oil field steam flood steam generators have been in use to aid in the recovery of heavy oil (ex. 13 API gravity) for more than forty years. These steam generators burn fossil fuels such as natural gas and in some cases some of the oil being produced to turn water into steam. The steam, which is injected into oil formations at very high pressures (up to 2,600 PSI), is allowed to mix with and heat the oil in the rock formations and thus reduce the viscosity of the oil. As a result the oil may be pumped to the surface more quickly and efficiently. Without steam injection oil fields in California, Indonesia, China, Russia, and Canada could not have economically produce the large quantities of oil they did over the past several decades. This method of oil production continues today and is now being employed in several parts of the world, which until now have not relied on steam injection to enhance oil production. These areas include fields in Oman and Kuwait.
The use of modern steam generators for oil production enhancement was pioneered in the oil fields of California following the 1970s oil embargo. The increasing oil prices justified the additional costs of steam generation to revive oil fields, which had previously been depleted of the easily produced light oil. While this technology dramatically increased oil production in California, it did so with a high environmental price. The use of crude oil to fuel the steam generators produced large quantities of Oxides of Nitrogen (NOx) and Carbon Monoxide (CO). These emissions had a severe negative impact on the already poor air quality in California. At the time oil fired steam generators produced as much as 175 PPM NOx and 2000 PPM CO.