Editing Compressed natural gas (section)

=== Locomotives ===
CNG locomotives are operated by several railroads. The [[Napa Valley Wine Train]] in the US successfully retrofitted a diesel locomotive to run on compressed natural gas before 2002.<ref>{{Cite news
| url=http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2002/11/22/NB43114.DTL
| title=Chugging along: After 13 years, Napa Valley Wine Train rolls to a profit - Jim Doyle - November 22, 2002
| access-date=2008-11-09
| work=The San Francisco Chronicle
| date=2002-11-22
| archive-date=2021-05-02
| archive-url=https://web.archive.org/web/20210502222557/https://www.sfgate.com/bayarea/article/Chugging-along-After-13-years-Napa-Valley-Wine-2715571.php
| url-status=live
}}</ref> This converted locomotive was upgraded to utilize a computer-controlled fuel injection system in May 2008, and is now the Napa Valley Wine Train's primary locomotive.<ref>
{{Cite web
| url=http://winetrain.com/news/node/4
| title=Napa Valley Wine Train Tests CNG Locomotive - Tech.Winetrain - May 15, 2008
| access-date=2008-08-20
| url-status=dead
| archive-url=https://web.archive.org/web/20090309134059/http://winetrain.com/news/node/4
| archive-date=2009-03-09
}}</ref> [[Ferrocarril Central Andino]] in Peru, has run a CNG locomotive on a freight line since 2005.<ref>{{Cite web
| url=http://www.treehugger.com/files/2005/06/the_first_cng_t.php
| title=The First CNG Train Starts Functioning in Peru - aula Alvarado - June 21, 2005
| access-date=2008-08-20
| archive-date=2009-03-05
| archive-url=https://web.archive.org/web/20090305140045/http://www.treehugger.com/files/2005/06/the_first_cng_t.php
| url-status=dead
}}</ref> CNG locomotives are usually [[diesel–electric transmission|diesel–electric]] locomotives that have been converted to use compressed natural gas generators instead of diesel generators to generate the electricity that drives the traction motors. Some CNG locomotives are able to selectively fire their cylinders only when there is a demand for power, which, theoretically, gives them a higher fuel-efficiency than conventional diesel engines. CNG is also cheaper than petrol or diesel fuel.{{CN|date=May 2023}}