Invited review
Introduction and advancement of a new clean global fuel: The status of DME developments in China and beyond

https://doi.org/10.1016/j.jngse.2012年05月01日2 Get rights and content

Abstract

The last two decades saw the emergence of a new multi-source, multi-market fuel, Dimethyl Ether or DME. Prior to 1990, DME had only found limited commercial use as an aerosol propellant along with propane and butane as a green replacement for the chlorofluoro-hydrocarbons which were outlawed because of their detrimental impact on the ozone layer. DME is an environmentally benign, non-toxic, biodegradable product with physical properties similar to LPG. Global DME annual production capacity is approximately 10 million metric tons and actual market use is reported to be about 3 million metric tons – a remarkable increase from the 200,000 metric tons market demand in the early 2000s. Nearly all of the DME is produced in China from coal-derived methanol via the well known catalytic dehydration process where two molecules of methanol react to form one molecule of DME and one molecule of water. DME is the fastest-growing methanol derivative, yet is still an emerging business with lots of upside opportunities combined with significant challenges. A number of other DME plants are in different stages of development around the world including Egypt, Middle East and Indonesia, all of them natural gas based. Sweden is the leader in the development of bio-DME produced through the gasification and conversion of black liquor, a byproduct in Sweden's paper and pulp industry.
Nearly all of today's DME is used as a blend stock for LPG which in turn is primarily used for cooking and heating. At blending levels below 20 vol %, the existing LPG blending facilities, local distribution infrastructure and end-use equipment can be used with minimal (if any) modifications – making for easy marketing. Currently, efforts are underway to commercialize DME as a high-quality diesel alternative. Technical issues such as new fuel injection systems and new fuel additives have been solved and solutions are currently being tested in fleets. This review will describe the history, status and future of DME as a global fuel alternative and how it has and will be changing the global methanol industry.

Introduction

In the seventies and eighties, oil embargos, increasing oil prices and the tremendous growth in stranded gas led to a worldwide R&D effort in finding new ways to monetize these gas resources by converting them into easily transportable, liquid fuels. Amoco (now BP), had a broad based effort into technologies producing both conventional fuels (gasoline, diesel) and novel fuels and fuel additives such as higher alcohols, DME, DMC (dimethyl carbonate) and "poly-DMM" (poly-dimethoxymethane, a range of dimethoxy-polyoxomethylenes) (Fleisch, 1995; Basu et al., June 2001; Fleisch and Sills, 2004). DME, in particular, was recognized as having significant potential as an environmentally-friendly alternative fuel for multiple markets, such as power generation, domestic home cooking, transportation, and as a chemical intermediate (Fleisch et al., 2001).
In 1995, extensive collaborative DME research efforts among Amoco, Haldor Topsoe and Navistar International Corp were reported that showed that DME could be a novel, low-emissions alternative fuel for diesel engines and could be manufactured at large-scale from methanol with a simple dehydration technology (Fleisch et al., 1995). Haldor Topsoe had developed a novel, robust technology to manufacture DME (Hansen et al., 1995). Amoco had sponsored an intensive DME diesel engine test program in a Navistar heavy duty engine, conducted by AVL-List GmbH, the largest engine testing laboratory in the world (Fleisch et al., 1995). The tests demonstrated the outstanding performance of DME as a diesel alternative and showed compliance with the most stringent California ULEV emissions regulations for medium-duty vehicles, as well as other advantages.
However, it was well understood that the development of the DME diesel market was challenging because of the necessary changes to the fuel distribution infrastructure and the modifications to the engines themselves. The obvious primary market was the blending with LPG because of the similar properties of DME and LPG. It was shown that blends of up to 20 vol % DME in LPG worked well in standard cooking and heating applications while higher concentrations necessitated the exchange of some polymeric seal materials. Similar blends performed well in automotive applications and were patented by Amoco (US Patent 5,632,786, 1997).
In search for additional markets, in the mid-to late 1990s, Amoco partnered with the General Electric Co. (GE), and in cooperation with the Electric Power Development Corporation of Japan (EPDC) tested DME as a gas turbine fuel (Basu et al., 2001; Fleisch et al., 2001; Basu and Wainwright, 2001). The results showed excellent performance with a measurable improvement in efficiency and the same low emissions as natural gas. Most importantly, GE offered guarantees for DME in most of their advanced turbines.
These test results along with other work clearly demonstrated that DME was a multiple market fuel for LPG blending, power generation and the diesel market. Furthermore, DME was known to be the chemical intermediate for novel pathways to hydrogen, olefins, acetic acid and gasoline. Based on this understanding, Amoco began global business development efforts (Fleisch and Sills, 2004; Fleisch et al., 2001). It engaged a number of Japanese power companies as well as engineering and shipping companies to initiate a global commercialization effort. Japan had played the lead role in creating the global LNG business and DME was considered as a new complementary fuel to LNG for monetizing remote gas resources.
DME as a new multi-purpose fuel was introduced to the world through press releases, press conferences and publications in 1995 (Fleisch et al., 1995). About fifteen companies and agencies from around the world expressed interest in sharing in work aimed at the commercialization of DME. TNO, the Dutch National Lab, offered to coordinate the global DME efforts by forming a "DME Interest Group", under the auspices of Annex XIV of the International Energy Agency, "Implementing Agreement", Alternative Motor Fuels. This group met quarterly, exchanged DME information and began the process of standardization. Group members included Amoco, Volvo Truck, AVL-List, Haldor Topsoe, AVL Powertrain, and Akzo Nobel (International Energy Agency/Automotive Motor Fuel Annex XIV, 2000).
Also in the mid- to late 1990s, Amoco studied a number of commercial opportunities, particularly marketing DME to India and Japan. In 1998, Amoco formed a joint venture with both the India Oil Company (IOC) and the Gas Authority of India (GAIL) (Fleisch et al., 2001). India was a country that needed DME in all three markets: LPG for cooking, an inexpensive power generation fuel (they were burning naphtha and had no access to LNG) and a much needed clean diesel alternative. The India joint venture identified the power market as the primary market because of its ease of entry and lower market risk. The LPG blending and diesel market were targeted for future DME trains after the appropriate technical demonstrations, regulatory work and development of standards were completed. Supply agreements were signed with several Indian power producers. Japan was the other market and the first DME utilization selected was power generation as an alternative to LNG. For gas access, the India DME joint venture held talks with several countries with large gas resources, particularly Qatar (Middle East Economic Digest, 2001). In December 1998, British Petroleum merged with Amoco, becoming BP Amoco until 2000, when the company was renamed BP plc. In 2001, BP decided to terminate the project due to other more favorable gas-related ventures (Dow Jones International News, 2001).
A global interest in DME had been awakened. The International DME Association (IDA) was formed in 2001. The Japan DME Forum (JDF) was formed to coordinate the multi-million dollar national effort. In the next few years, two more national forums had been formed, namely the Korea DME Forum (KDF) and the China DME Association (CDA). Information was shared in both regional Asian meetings and in international DME meetings.
The CDA concentrated on commercialization for several reasons. Firstly, the demand in China for additional home cooking and heating fuel was large, and the DME distribution and marketing was relatively simple through blending into LPG using existing local cylinder filling and distribution infrastructure and marketing channels. Secondly, there was and still is a clear government mandate to use the domestic resource coal as a feedstock for chemicals and clean fuels. Thirdly, too many coal-to-methanol plants had been built resulting in a large oversupply of methanol, the feedstock for DME manufacture, leading to near-term profit opportunities. Fourthly, the low capital investment for methanol to DME plants and the first mover advantage were strong stimulants for smaller energy companies and entrepreneurs to enter the lucrative fuel business. Finally, the absence of well established industry standards for blending DME into LPG was not a hindrance to a successful business development. History has shown that the Chinese authorities and business world are quick in adapting new technologies and products.
In summary, China, a relative late-comer in DME, has established herself as the unrivaled leader in DME production and use. In 2010, 9 metric tons per year of the total 18 metric tons per year of methanol used in China went into the fuel market; that is, DME, MTBE and some direct gasoline blending. Clear government plans for the use of coal to products, business savvy, the availability of capital and the willingness to quickly embrace new technologies and ideas have made China the leader in DME.

Section snippets

DME: the markets

As DME has been commercially used as a high-grade propellant for various health care product, its environmental, health and safety (EHS) characteristics are rather "impeccable" (vs. conventional petroleum-based fuels) for its use as a multi-purpose fuel and as a chemical intermediate. DME is a flammable, thermally-stable liquid like LPG and can be handled like LPG with similar safety guidelines and codes as LPG. A few key physical properties of DME are compared with specific conventional fuels

DME manufacturing technologies

For effective monetization of fossil-based coal and natural gas resources, especially if various government mandates for CO2 capture and sequestration (CCS) are enacted in the future for a specific site, DME would need to be produced in relatively large quantities; that is, at 3000–7500 metric tons/day DME capacities, to enhance overall project economics. For biomass-based DME manufacturing, where the key current market drivers are the concerns for climate change and energy security for

General

The challenges to successfully commercializing a new fuel such as DME are formidable, primarily due to competition from not only established conventional fuels with distribution and marketing infrastructures but also other alternative fuels. A significant challenge involves the risks inherent in building commercial-scale production and distribution facilities before the market is fully developed. DME has been able to overcome this challenge due the relative simplicity of (1) making DME from

Environmental, health and safety (EHS) issues

Companies manufacturing, distributing and marketing DME as a new fuel have to comply with all existing regional and federal environmental, health and safety laws and regulations. These laws and regulations govern the production, handling, storage, transportation and end-use of DME.
Whereas a detailed discussion of EHS issues is beyond the scope of this article, in general, EHS issues for DME can be summarized as:
  • •
    Environment.
    • ○しろまる
      Low emission fuel
    • ○しろまる
      Does not deplete ozone (Creazzo, 2005)
    • ○しろまる
      Has minimal

Economics from natural gas and coal

The business opportunity provided by DME as a new fuel can be understood by determining the economics for the supply chain including the feedstock resource, DME production, and transportation to the regional market. The economics for methanol are also shown, since these economics are more readily estimated and methanol represents most of the cost of DME. The economics for both natural gas-derived DME and coal-derived DME have been estimated (Year 2011 $) since methanol is primarily derived from

Concluding remarks

  • •
    Today's high oil prices and the large gas/oil and coal/oil spreads lead to an economically attractive environment for gas and coal conversion processes. This is evidenced by the emergence of a material and healthy GTL (Gas-to-Liquids) and CTL (Coal-to-Liquids) business ranging from Qatar to China. An even stronger driver for the commercialization of DME is energy independence as mandated by China and the resulting build-up of a huge coal-based conversion industry centering on methanol. Yet

Acknowledgements

Dr. Arun Basu would like to thank the management of the Gas Technology Institute (Des Plaines, Illinois, USA), specifically Mr. Howard Meyer (Director, Gas Processing Group) and Mr. Vann Bush (Managing Director, Gasification and Gas Processing Division), for their encouragement in writing this article jointly with Dr. Theo Fleisch and Dr. Ronald Sills.

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