The following is an excerpt from a Technical Research Proposal I helped to develop and submit in conjunction with the National Alternative Fuels Foundation (now defunct). Although some of the content is a bit dated, it speaks to a promising pathway to lower gasoline costs and provide clean energy from other sources such as coal, natural gas and biomass (assuming research success).
Background & Research Concept (The Need, The technology and its Benefits, Research)
Dimethyl Carbonate (DMC) is a biodegradable, high-octane compound that can be used to significantly reduce U.S. dependency on foreign oil, assuming an economically feasible and environmentally acceptable catalyst and process for its manufacture. The research project described in this proposal (“Research”) will explore two catalytic/process pathways that have a high probability of achieving this end. These pathways (assuming success) would enable economically production of large quantities of DMC from synthesis gas or methanol (either of which can be produced from renewable biomass, including forest products and agricultural wastes, as well as from domestic coal or natural gas) and sequestered CO2.
There is a need for a domestically produced, renewable fuel to reduce national dependency on imported fuels.
In 1985, imported petroleum represented only 4 million barrels/day (hereinafter “b/d”) or 27% of US domestic consumption. In 2002, it represented nearly 11.4 million barrels per day or 58 % of US domestic consumption. At the same time, US dependency on Middle East oil increased by more than five times to approximately 2.3 million b/d (from .35 million b/d). In-spite of improvements to today’s energy diversity, a clear and present need exists to reduce this dependency, while simultaneously mitigating environmental risk.
An emission-reducing low-cost fuel component that can replace MTBE and be used immediately in existing vehicle/ fuel distribution system, absent engine or system modification, is needed.
DMC can be blended into gasoline at the refinery level and utilized within existing fleet and fuel distribution systems without modification or retrofit. It has the potential to improve the combustion and fuel efficiency of the entire gasoline pool, simultaneously reducing harmful emissions. MTBE was phased out due to concerns over its toxicity and groundwater contamination. The other major oxygenate, ethanol, while environmentally sound fuel, is solely dependent upon tax subsidy, and has deleterious hydroscopic tendencies, which make it unsuitable for pipelines. Furthermore, ethanol is not readily used in diesel, fuel oils and/or aviation fuels.
DMC is a low vapor pressure, low-toxicity, higher boiling point, non-hygroscopic, fully miscible/fungible fuel component, having attractive octane, cetane and emissions characteristics, especially when used in gasoline, diesel, fuel oils, aviation and other transportation fuels. DMC can be manufactured from domestic and renewable feedstock, transported in existing fuel pipelines and be used without any modification to engines or fuel distribution systems.
There is a need for a New Fuel and supplement to Ethanol?
US refining capacity is close to maximum capacity and ethanol production has recently declined. The “newest” refinery in the United States began operating in 2008 in Douglas, Wyoming. However, the newest refinery with atmospheric distillation capacity greater than 100,000 barrels per day began operating in 1977 in Garyville, Louisiana (source: EIA). As energy demand is likely to increase, octane costs associated with high severity processes, shrinking the pool even more is likely to persist beyond the replacement potential of Ethanol.
A large viable economic fuel use of sequestered CO2 is needed.
Due to environmental greenhouse concerns, there is justification to remove and sequester large quantities of CO2. However, there is a challenge in finding acceptable places to dispose of CO2. If successful, the proposed catalyst/process would use massive amounts of CO2 as feedstock. The prospect of such significant CO2 use in the economic production of transportation fuels represents a break-through in alternative fuel production.
There is a need for a hydrogen carrier fuel (HCF) that is safe, affordable, and widely distributable before the US’s conversion to a hydrogen economy:
Title VIII Hydrogen provisions require the DOE to encourage programs that would facilitate the production of hydrogen carrier fuels from diverse sources, and to support the research, development, and demonstration activities necessary to meet these program goals. DMC is potentially one of the most attractive hydrogen carrier fuels anywhere. It is potable, relatively non toxic and can be manufactured from a host of different feeds (assuming success of this project). As additive to hydrocarbon fuels, it could drive the creation of large-scale HCF production facilities, enable utilization of existing distribution systems, and create the preexisting HCF supply necessary for easy transition to a hydrogen fuel economy.
There is a need for a safe, potable, low toxic, fungible, non-hygroscopic fuel for future fuel cell vehicles.
Some experts agree that the ultimate solution for a clean, sustainable transportation system will be a conversion from internal combustion engines to fuel cells. Methanol and hydrogen are both currently used in fuel cells. However, each has it limitations. Methanol is toxic and highly hydroscopic (therefore not fungible). Hydrogen, on the other hand, is a gas that requires special handling, which is highly explosive. DMC, is a potable liquid, which is a non-hygroscopic/fully fungible, relatively non-explosive and non-toxic, essentially consisting of two molecules of methanol and one of CO2.
“Toyota is moving away from building longer-range battery-electric vehicles (EV) in favor of its effort in hydrogen fuel cell vehicles, its top North American executive said. Jim Lentz, CEO of Toyota’s North American region, said Toyota sees battery-electric vehicles as viable only in “a select way, in short-range vehicles that take you that extra mile, from the office to the train, or home to the train, as well as being used on large campuses.” 5/20/2014 autonews.com
The Technology and its Benefits (Advantages over current technologies)
The benefits a potential new pathway for the safe and economical (fuel commodity) production of DMC are substantial and many. They fall into two categories: “process benefits” and “usage benefits.” Each of these includes “stand-alone” and “combined technology” benefits, as discussed below:
Stand alone process benefits
These benefits are defined as those based solely on production/use of DMC as a refinery stream component:
Reduction in the use/or supplement of petroleum based fuels from DMC produced from natural gas, coal, biomass feedstock (either directly or indirectly via methanol or ethanol) and CO2
These feedstock are not traditional petroleum material and represent alternative fuel sources. As a fuel additive DMC could easily replace/supplement the equivalent of 4.47 million barrels per day of finished US petroleum products within the next decade (1.48 million b/d biomass, 0.490 sequestered CO2, 2.5 million b/d natural gas or coal).
DMC from Biomass
The DOE estimates over 2.45 billion metric tons of biomass are available for methanol conversion each year . Assuming a 5% conversion rate, an additional 1.48 million b/d of methanol derived from biomass could be produced within the next decade. Given the expected conversion rates, DMC catalyst process should be the same as methanol’s. Thus, 1.48 million b/d of DMC could be realistically produced from biomass within the next decade.
DMC Produced from Sequestered CO2
Proposed DMC reaction pathway (equation 11 Appendix 1), will utilize CO2 as a feed material. For every 1.0 kilogram (kg) of DMC produced 0.5 kg of sequestered CO2 will be consumed. The use of sequestered CO2 to produce DMC effectively reduces energy/fuel otherwise required to produce CO2 from non-sequestered sources. This translates into annual energy process savings of 0.89 quadrillion BTU (or about 490 thousand b/d) within the next decade. Moreover, the net effect of using sequestered CO2 and biomass in the production of DMC, effectively results in net zero CO2 emissions when DMC is ultimately combusted as additive.
DMC from Natural Gas
The quantity of recoverable natural gas in the United States is vastly greater than that of petroleum. To the extent clean natural gas can substitute for petroleum feedstock in transportation fuels, it could greatly improve both our domestic energy and environmental sustainability. Alternatively, clean coal syn-gas may be used. A successful DMC production pathway from synthesis gas or methanol will create an unprecedented use for natural gas or clean coal syn-gas with a realistic potential of displacing 2.5 million b/d of the US petroleum based fuels by 2020. According to Lurgi (a proposed industry process engineering contractor – see below) by 2030, the share of European petroleum-based fuels will drop from its current 90% to below 40%, while the share of natural gas-based synthetic fuels will rise by a similar percentage.
2.) Significant reductions in environmentally harmful by-products and energy requirements (compared to current DMC processes)
Reductions in environmentally harmful by-products:
Compared to the phosgene DMC process, based on the NAFF’s proposed catalyst/process pathways, there is a reduction of 1.3 g of NaCl per g of DMC formed, as well as the elimination of hazardous HCL as a byproduct.. Additionally, because CO2 is used instead of CO and NO, the risk of explosion and accidental release of toxic CO and NO during manufacture is virtually eliminated.
Reduced Energy Requirements
Current DMC production technologies are geared more for pharmaceutical grade production, and hence are energy/capital intensive, unable to deliver DMC in volume and at prices competitive to other fuel additives (ethanol, MTBE, and petroleum based octane enhancers).
Under NAFF’s proposed development plan, stringent decision points will be required/maintained (see below) to insure that critical yields/costs can be demonstrated (to insure that NAFF’s catalyst/process can distinguished over the existing uneconomical processes) prior to entry into Phase II catalyst improvement/development, or Phase III pilot plant feasibility studies. Anticipated reductions in energy requirements are dependent upon selected starting material, catalytic efficiency and process conditions. [It is believed Dow invested $8MM in DMC process research, which lead to energy cost reductions from over $1.00/lb to less than $0.10/lb, before abandoning its effort in the mid 1980’s after MTBE became the premier oxygenate. A NAFF team member [Harold Myers] was intimately involved in Dow’s effort. Another team member [Dr. Scott Cowley] was intimately associated with another big dollar dialkyl carbonate catalyst/process initiative. Based on the combined expertise of NAFF’s team, which has benefited from substantial preexisting research, that NAFF’s proposed research pathways could result savings of between 58 and 93 percent over existing DMC processes. Such savings are necessary if DMC is to become a low cost commodity fuel or fuel additive.
Usage Benefits (benefits associated with the use of DMC as a Fuel Additive)
DMCrepresents a new, commercially-viable pathway for the creation of a near-term hydrogen carrier fuel production. Furthermore, this pathway may represent the safest, fastest, and potentially the most cost-effective way to deliver hydrogen into the marketplace.
Why the safest? Unlike pure hydrogen or compressed natural gas, DMC does not require costly/potentially dangerous high-pressure storage and delivery tanks. For safety reasons, federal regulations prohibit siting hydrogen-fueling equipment within 75 feet of gasoline fueling equipment, effectively pushing hydrogen out the footprint of most existing energy retailers. Moreover, the storage of gaseous hydrogen at pressures of 5,000 to 10,000 psi on board vehicles represents a considerable danger, since a traffic accident or an intended act of terrorism could rupture the storage tank and cause a large explosion, potentially killing hundreds.
Ethanol, MTBE, and natural are among the leading commercial hydrogen carrier fuels currently in the marketplace. Like DMC, ethanol and MTBE do not require high-pressure storage/transport and delivery tanks. However, MTBE will gradually be phased out. Ethanol, a safer alternative is limited due to feedstock limitations and need for Federal subsidies. Natural gas requires special handling and distribution facilities. Conversion of natural gas, and MTBE to hydrogen yields CO2, a green house gas. The conversion of DMC to hydrogen would not yield any new CO2, as sequestered CO2 was the original feed.
Why the Fastest? Safe and economical “near term” fuel additive demand for DMC will drive plant construction. Given DMC’s superior energy and environmental advantages, DMC supplies will likely grow faster than any other HCF.
Why the most cost effective? Domestic natural gas prices are now quite high. Reliance upon natural gas as the premier HCF (even assuming cost effective hydrogen conversion) would translate into extremely high hydrogen fuel costs. Other the hand, relying upon DMC, which can be produced from a basket of feed stock material, including biomass and coal, would tend to hedge against price swings of a single feed. Furthermore, unlike hydrogen or any other commercially available hydrogen carrier fuels, DMC is the only fuel that can be used safely and seamlessly in current transportation fleets and fuel distribution networks. The US fuel distribution system is a major piece of our national energy infrastructure. Replacing it with a separate hydrogen system will require massive expenditures. (Unlike natural gas or hydrogen, DMC can be supplied at existing fueling facilities and be potentially utilized in a yet to be invented “on board” hydrogen fuel conversion/energy system, negating the hazards of converting to hydrogen before delivery).
• Superior Oxygen content can translate into superior emission benefits
DMC’s superior oxygen content can result in significantly lower CO2, CO, NOx, and toxic emissions. DMC contains 53.3% oxygen by weight, far greater than any other available oxygenate. By comparison, ethanol contains 34.8% oxygen by weight, and MTBE contains 18.2% oxygen by weight. According to the EPA: “Oxygen helps gasoline burn more completely, reducing harmful tailpipe emissions from motor vehicles. In one respect, the oxygen dilutes or displaces gasoline components such as aromatics (These aromatics such as benzene are responsible for disproportionate amounts of carbon monoxide and hydrocarbon exhaust emissions) and sulfur. In another respect, oxygen optimizes the oxidation during combustion. Oxygenates can increase the combustion efficiency of gasoline, thereby reducing vehicle emissions of carbon monoxide. ” It has been established that tail pipe emissions are generally independent of the type of oxygenate added to gasoline (Reuter et al 1992), thus making DMC the most valuable oxygenate on a weight basis, assuming all else is equal.
• DMC has low toxicity and is biodegradable.
Unlike MTBE, there is no ground water contamination risk associated with DMC as a fuel additive. DMC is biodegradable and reacts in the presence of a catalytic amount of base thereby avoiding the formation of undesirable inorganic salts as by-products. Unlike MTBE and certain petroleum-based fuels, DMC is not especially carcinogenic. In laboratory toxicology tests, the lethal dose of DMC required to kill 50% of rat population is 13,000 mg/kg, more than 3.25 the amount of MTBE (4000mg/kg) required.
• DMC has no transportability or RVP disadvantages (unlike ethanol)
Transportability Advantages: Unlike ethanol, DMC is not hydroscopic and does not separate from gasoline if stored for an extended period of time, or if exposed to water or water vapor (as in a pipeline). Because of its inherent problems, ethanol is shipped separately from gasoline (typically by rail car or truck but not in pipelines) and is blended with the gasoline at the distribution terminal. This disability costs ethanol 2 cents a gallon or more, in terms of additional handling.
RVP Advantages: EPA regulates the vapor pressure of all gasoline during the summer months (June 1 to September 15 at retail stations). These rules reduce gasoline emissions of volatile organic compounds (VOC) that are a major contributor to ground-level ozone. DMC is a desirable fuel additive because (unlike ethanol) it does not increase fuel vapor pressure (evaporative emissions), which makes it particularly attractive in RFG fuels. With DMC, low cost, high vapor pressure components such as butane and pentanes may not need to be removed, translating into greater profitability and reduced petroleum waste. (See Attachment 1, Letter from Herb Bruch, Former Technical Director, National Petroleum Refiners Association)
Why a DMC pathway from Methanol?
Methanol, a chemical that may be produced from biomass, coal, fuel oil, or natural gas is likely to be the principal feedstock in NAFF’s DMC catalyst/process effort. According to the Methanol Institute, US methanol capacity totals 2.2 billion gallons/annually, meeting ¾’s of US demand, of which, MTBE production accounts for 41%.
Because of MTBE phase out, methanol prices have softened. At the same-time, at least 12 million tonnes/year (88 million barrels) of new capacity worldwide is expected. Chemical Market Associates predicts a significant over capacity of methanol will exist, unless a new market is found/created.
Assuming success of NAFF’s effort, limited industrial-scale production of DMC could be in place as early as 2008. In view of the anticipated increases in both domestic and worldwide methanol capacity, as well as the phase-out of MTBE, methanol should be in sufficient quantities for the near term and intermediate production of DMC. Intermediate and longer term DMC production from methanol will almost certainly require significant new methanol production.
Why a DMC pathway from Synthesis gas?
While technically more challenging, DMC produced directly from syn-gas represents the lowest possible cost option (One-Step Syn-Gas Process). Biomass syn-gas to DMC would be a highly desirable option and is an integral component of NAFF’s Research effort. Lurgi would be a particularly suitable down-stream process engineering contractor, due to their experience in biomass and other synthesis gas to methanol.
Notes
EIA country [US] Analysis Brief October 2003 at http://www.eia.doe.gov/emeu/cabs/usa.html
This is defined as benefits associated with a successful DMC process development according to proposed catalytic pathways, the use of desired feedstocks, and projected market conditions.
http://www.ott.doe.gov/biofuels/pdfs/methanol_from_biomass.pdf (1995)
According to DOE: “One ton of biomass feedstock can be converted to 721 liters (186 gallons) of methanol.” Source: http://www.ott.doe.gov/biofuels/pdfs/methanol_from_biomass.pdf
Given the current availability of sequestered CO2 coupled with the fact that through international mandates, sequestered CO2 capacity is quickly emerging, it is anticipated that sufficient CO2 will be commercially available at competitive prices to meet 100% of the capacity to produce DMC derived from a biomass feedstock by 2024.
This assumes that the marketplace for sequestered CO2 will be sufficiently large and prices competitive.
On a BTU energy basis, the energy available from US proven natural gas reserves (183 TCF) exceeds the amount of available energy from US proven petroleum reserves (22.4 billion barrels) by approximately 182,900 quadrillion BTU (or 1694 times) (5.83 mbtu = 1 barrel petroleum, 1000 cuft= 1MBTU natural gas) sources EIA country Analysis Brief October 2003 and EIA “Apples, Oranges and Btu” doc at http://www.eia.doe.gov
“Official Inauguration of the HP POX High Pressure Synthesis Gas Plant Built by Lurgi and the IEC in Freiberg on 21 November 2003” at http://www.lurgi.com/english/nbsp/index.html
EIA, “ Motor Gasoline Outlook and State MTBE Bans” Table 1 , April 6,2003 at http://www.eia.doe.gov
Increased olefins translate into increased profitability due to decreased processing requirements in addition to the cost savings associated with the reduced amount of paraffin required.
Reduced aromatic content is not required to meet complex model emissions under Phase II of CAA as long as VOC’s and NOx emissions are met.
Dolan, Gregory “In search of the Perfect clean-fuel options” Hydrocarbon Processing, March 2002 at http://www.methanol.org/pdf/HP03Editorial.pdf p.2
Pacheco, Michael A. “Review of Dimethyl Carbonate Manufacture and Its characteristics as a Fuel additive” Table 5 American Chemical Society, 1997.
http://www.epa.gov/mtbe/faq.htm
Cleaner Gasoline for Cleaner Air Better for Your Health EPA 420-F-95-005 April 1995 EPA Office of Mobile Sources at http://www.epa.gov/otaq/rfgheal.htm
Tundo P. “New Developments in DMC chemistry” pure Appl Chem Vol. 73 No.7 pp.1117,2001 at http://www.iupac.org/publications/pac/2001/pdf/7307×1117.pdf
Oxford Physical and Theoretical Chemistry Lab
http://physchem.ox.ac.uk/MSDS/DI/dimethyl_carbonate.htmland http://ptcl.chem.ox.ac.uk/MSDS/BU/tert-butyl_methyl_ether.html
http://www.eia.doe.gov/emeu/steo/pub/special/mtbeban.html#MTBE%20Supply%20and%20Demand
http://www.epa.gov/otaq/volatility.htm
Katrib Y. “Uptake measurements of carbonates by aqueous phase” Universite louis Pasteur, Strasbourg at http://imk-aida.fzk.de/CMD/AR2000/HEP06.pdf
The Federal RFG program requires a minimum 2.1 percent oxygen by weight when averaging. This minimum oxygen requirement can be satisfied by blending approximately 5.5 volume percent ethanol or 11 volume percent MTBE.
http://www.eia.doe.gov/emeu/steo/pub/special/mtbeban.html#MTBE%20Supply%20and%20Demand
http://www.methanol.org/methanol/fact/methanol.cfm
Oil & Gas Journal Week of November 17’th 2003 (Industry Trends) p.7
It is anticipated that the catalyst/pathway converting methanol into DMC would also likely include an ability to convert ethanol into diethyl carbonate (DEC). Thus, ethanol may also be included as a possible feed, if DEC was the desired product.
wdavidorr 