|China’s first dimethyl ether bus, made by Shanghai Jiaotong University.|
Xinhua. The Chinese government will support the development of dimethyl ether (DME), a gas derived from coal, as a possible alternative to diesel. A circular from the National Development and Reform Commission (NDRC) said standards for the use of DME as a civil fuel were being drawn up.
DME is an LPG-like synthetic fuel that is produced through gasification of coal or various renewable substances. The synthetic gas is then catalyzed to produce DME. A gas under normal pressure and temperature, DME can be compressed into a liquid and used as an alternative to diesel. Its low emissions make it relatively environmentally friendly.
The circular form the NDRC said that DME was expected to become a major fuel and was suitable for China’s energy structure. DME-fueled vehicles have been developed by Shanghai Jiaotong University and Xi’an Jiaotong University as well as in Japan and the European Union.
The Xinhua-run China Securities Journal reported on Wednesday that Shanghai Municipality planned to open the first DME-fueled bus line this year and operate 1,000 such vehicles before the World Expo in 2010. (Earlier post.)
The China Securities Journal said China’s estimated annual DME output from planned refineries was 500,000 tons. Water resources and capital were the main restrictive factors as production of one ton of DME would use as much as three tons of water.
The NDRC suggested at a meeting in June that policies for the development of DME and establishment of industrial standards be accelerated.
In December 2005, Japan’s Toyo Engineering announced that it will design and build China’s first major coal-to-dimethyl ether (DME) plant with China’s Ningxia Coal Group in northwestern China’s Ningxia Hui Autonomous Region. (Earlier post.)
|Physical properties and combustion characteristics of DME|
|Boiling point (ºC)||-25.1||-42.0||-161.5||180–370|
|Liquid density (g/cm3 @20ºC)||0.67||0.49||0.42||0.84|
|Liquid viscosity (kg/ms @25ºC)||0.12–0.15||0.2||–||2–4|
|Specific gravity of gas (vs. air)||1.59||1.52||0.55||–|
|Vapor pressure (MPa @25ºC)||0.61||0.93||–||–|
|Explosion limit (%)||3.4–17||2.1–9.4||5–15||0.6–6.5|
|Net calorific value (MJ/Nm3)||59.3||91.0||35.9||–|
|Net calorific value (MJ/kg)||28.8||46.3||49.0||42.7|