Methanol

Methanol is a realistic alternative to the Hydrogen Economy. Its more toxic, but as a liquid, its easier to transport and store. Unlike hydrogen, it can be distributed via the same transport systems used for oil. Additional benefits are that:

• most of the technology for using methanol as a fuel already exists
• like hydrogen, it can be used directly in fuel cells to generate electricity
• internal combustion engines can be modified to run on it.

A common feature of methanol, hydrogen and biofuels is that all three are just ways of storing and transporting energy. They are not primary energy sources because they all require large amounts of externally provided energy to pumped into them during manufacture.

Synthesis from natural gas

This is the current industrial production method but it is only a viable methanol source while natural gas can be obtained from fossil sources.

Pyrolytic decomposition of wood

This method was introduced in 1927 and used to produce methanol as a fuel until it was displaced by oil-based fuels. A pyrolytic reactor is operated as a gasifier by injecting air or pure oxygen into the reactor core. This burns the biomass to ash and releases gasses. After scrubbing, the resulting syngas which is a mixture of hydrogen and carbon monoxide in an approximately 2:1 ratio, is reacted in the presence of catalysts at high pressure and temperature to form methanol. This method produces about 100 gallons of methanol per ton of feed material. This process is carbon neutral because the methanol is derived from biomass.

Synthesis from carbon dioxide and water

This process can be powered by nuclear or renewable energy. It should be non-polluting and carbon neutral because the only products are methanol and oxygen. At the time of writing (November, 2012) there is one proof of concept system running:

• Air Fuel Synthesis, a British start-up, is developing a process for producing petrol from atmospheric carbon dioxide and water:
  • Carbon dioxide is captured by blowing the air into a sodium hydroxide mist, which yields sodium carbonate and water.
  • Water is split by electrolysis to get hydrogen.
  • Optionally, water from the atmosphere can be used. This is obtained by cooling the incoming air and passing it through a condenser.
  • Carbon dioxide is combined with hydrogen to form methanol.
  • Methanol is then converted to petrol via the Mobil methanol-to-gasoline (MTG) process.

  The sodium hydroxide appears to be recycled, though neither the waste products nor the process energy efficiency are mentioned. Their development timetable calls for plants capable of producing at least 10 tonnes of renewable fuel a day by 2015: the current (2012) demonstrator produces one litre of petrol per day.

  The MTG process is proven technology which has been in use in New Zealand since 1985. Unlike the better known Fischer-Tropsch process, which needs significant energy input and, as a result, has overall energy efficiency in the 25-50% range, the MTG process is exothermic and 93% of the energy contained in the methanol is retained in the final product.

• There is a similar, but less advanced, project being run by a Saudi firm in conjunction with Peter Edwards of Oxford University's chemistry department.

The critical factor for this fuel production path is its energy efficiency, but nobody is willing to discuss that. Yet.