Methanol economy
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The methanol economy is a hypothetical future economy in which methanol has replaced fossil fuels as a means of transportation of energy. As a proposal, it offers an alternative to also still hypothetical hydrogen economy, ethanol economy, or vegetable oil economy. In 2005, Nobel prize winner George A. Olah published an essay advocating the methanol economy.[1] He lists arguments against the hydrogen economy and discusses the generation of methanol from carbon dioxide or methane.
Methanol can be used directly as fuel (including in hybrid cars) or in a direct methanol fuel cell. It can be made from hydrogen in a greenhouse neutral process and used in place of hydrogen, without construction of new hydrogen infrastructure.
A source of carbon dioxide to synthesize methanol in a recycling process could in theory be from the earth's atmosphere but given the low concentration (0.037%) it would require the development of an efficient semipermeable membrane technology. Other sources are the exhaust of fossil fuel power plants which would otherwise be released into the atmosphere, not being economically viable to retrofit into systems for carbon capture and storage.
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[edit] 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
[edit] Theoretical advantages over other energy storage media
[edit] Advantages over hydrogen
Methanol economy advantages compared to hydrogen:
- efficient energy storage (by volume) and also by weight when hydrogen confinement vessel taken into account.
- 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
[edit] 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
[edit] 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). [2] 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 (unlike straight vegetable oil) but methanol toxicity is actively researched [3]
- 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. [4]
[edit] See also
[edit] References
- ^ Beyond Oil and Gas: The Methanol Economy George A. Olah Angewandte Chemie International Edition Volume 44, Issue 18, Pages 2636-2639, 2005
- ^ Abstract
- ^ 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).
- ^ Abstract
[edit] External links
- A discussion of the Methanol Economy with George Olah Recording of a program broadcast on NPR.
- Methanol Institute
