Methanol economy

The methanol economy is a suggested future economy in which methanol replaces fossil fuels as a mean of energy storage, fuel and raw material for synthetic hydrocarbons and their products. It offers an alternative to the proposed hydrogen economy or ethanol economy.

In 2005 Nobel prize winner George A. Olah advocated the methanol economy in an essay ^[1] and in 2006 he and two co-authors published a book around this theme ^[2] In these publications, they summarize the state of our fossil fuel and alternative energy sources, their availability and limitations before suggesting a new approach in the so called methanol economy.

Methanol, is a fuel for heat engines and fuel cells. Due to its high octane rating it can be used directly as a fuel in cars (including hybrid and plug-in vehicles) using existing internal combustion engines (ICE). Methanol can also be used as a fuel in fuel cells, either directly in Direct Methanol Fuel Cells (DMFC) or indirectly after conversion into hydrogen by reforming.

Methanol is a liquid under normal conditions, allowing it to be stored, transported and dispensed easily, much like gasoline and diesel fuel nowadays. It can also be readily transformed by dehydration into dimethyl ether, an diesel fuel substitute with a cetane number of 55.

Methanol is already used today on a large scale (about 37 million tonnes per year)^[3] as a raw material to produce numerous chemical products and materials. In addition, it can be readily converted in the methanol to olefin (MTO) process into ethylene and propylene, which can be used to produce synthetic hydrocarbons and their products, currently obtained from oil and natural gas.

Methanol can be efficiently produced from a wide variety of sources including still abundant fossil fuels (natural gas, coal, oil shale, tar sands, etc.), but also agricultural products and municipal waste, wood and varied biomass. More importantly, it can also be made from chemical recycling of carbon dioxide. Initially the major source will be the CO₂ rich flue gases of fossil fuel burning power plants or exhaust of cement and other factories. In the longer range however, considering diminishing fossil fuel resources and the effect of their utilization on earth's atmosphere, even the low concentration of atmospheric CO₂ itself could be captured and recycled via methanol, thus supplementing nature’s own photosynthetic cycle. Efficient new absorbents to capture atmospheric CO₂ are being developed, mimicking plant life’s ability. Chemical recycling of CO₂ to new fuels and materials could thus become feasible, making them renewable on the human timescale.

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Synthesis

In the methanol economy, methanol is synthesized:

• by carbon dioxide recycling with hydrogen or with water in an electrochemical process (this is greenhouse neutral if the carbon dioxide would have been emitted)
• by oxidation of methane (present in as yet untapped methane clathrates. Also untapped are the vast amounts of methane currently bubbling up from thawing tundra in Siberia.) with oxygen and a suitable catalyst

Theoretical advantages over other energy storage media

Advantages over hydrogen

Methanol economy advantages compared to hydrogen:

• efficient energy storage (by volume) and also by weight as compared with compressed hydrogen, when hydrogen pressure-confinement vessel taken into account. Methanol is considerably more efficient than liquid hydrogen, in part because of the low density of liquid hydrogen of 71 grams/liter. Hence there is actually more hydrogen in a liter of methanol (99 grams/liter) than in a liter of liquid hydrogen, and the methanol hydrogen needs no cryogenic container.
• required hydrogen infrastructure would be prohibitively expensive; methanol can be directly cycled into existing gasoline infrastructure
• can be blended with gasoline
• user friendly (hydrogen is volatile and requires high pressure system confinement)
• methanol serves as a raw material for the chemical industry

Methanol economy advantages compared to ethanol

• can be made from any organic material using the proven Fischer Tropsch method of synthesis gas catalysis
• can compete with and complement ethanol in a diversified energy marketplace

Theoretical methanol economy disadvantages

• high energy costs associated with generating hydrogen (when needed to synthesize methanol)
• generation in itself not clean
• presently generated from syngas still dependent on fossil fuels (although in theory any energy source can be used).
• energy density (by weight or volume) one half of that of gasoline
• corrosive to aluminum, importantly aluminum parts in engine fuel-intake systems
• hydrophilic: attracts water, which can create solid jelly-like obstructions in fuel-intake systems (in cold weather), which is corrosive, and which can separate into a non-combustible component
• methanol, as an alcohol, increases the permeability of some plastics to fuel vapors (e.g. high-density polyethylene). ^[4] This property of methanol has the possibility of increasing emissions of volatile organic compounds (VOCs) from fuel, which contributes to increased tropospheric ozone and possibly human exposure.
• low volatity in cold weather: methanol-fueled engines can be difficult to start, and they run inefficiently until warmed up
• Methanol is generally considered a toxin^[5]
• methanol is a liquid: this creates a greater fire risk; unlike hydrogen and other gases, methanol leaks do not dissipate
• methanol accidentally released from leaking underground fuel storage tanks may undergo relatively rapid groundwater transport and contaminate well water, although this risk has not been thoroughly studied. The history of the fuel additive methyl t-butyl ether (MTBE) as a groundwater contaminant has highlighted the importance of assessing the potential impacts of fuel and fuel additives on multiple environmental media. ^[6]

See also

• Alcohol fuel
• Methanol
• Methanol fuel

References

1. ^ Beyond Oil and Gas: The Methanol Economy , George A. Olah, Angewandte Chemie International Edition Volume 44, Issue 18, Pages 2636-2639, 2005
2. ^ Beyond Oil and Gas: The Methanol Economy , George A. Olah, Alain Goeppert, G. K. Surya Prakash, Wiley-VCH, 2006
3. ^ Product Focus: Methanol, Chemical Week May 23, 2007, Pages 29
4. ^ Abstract
5. ^ Methanol is a developmental and neurological toxin, though typical dietary and occupational levels of exposure are not likely to induce significant health effects. The a National Toxicology Program panel recently concluded that blood concentrations below approx. 10 mg/L there is minimal concern for adverse health effects.[1] Other literature summaries are also available (see, for instance, Reproductive Toxicology 18 (2004) 303–390).
6. ^ Abstract