Methanol: The Basic Chemical and Energy Feedstock of the Future

The planet Earth is a sphere with a limited surface of 5 × 10¹³ m², of which 71 % is water and only 29 % is land. A total of 27.5 % of the landmass (i.e. 11 % of earth’s surface) is used as arable acreage, 20.8 % as pasture, and 9.4 % is used to grow timber. The remaining surface, which mainly is made up of deserts and mountains, is unused: 10.1 % is a frozen surface and 2.0 % is inland water. Meanwhile, the human population requires not less than 7 % of the land—a number that is constantly growing at the expense of the arable landmass. In fact, the usable area has been diminishing for years.

Dwindling fossil feedstock reserves such as crude oil, natural gas, brown coal (lignite) and coal in addition to the global warming caused by CO₂ emissions have necessitated a search for alternatives for energy and feedstocks for the chemical industry (material and energetic uses). The depletion points of fossil raw materials and their impacts are discussed. Alternatives such as biomass and sun-derived renewables yielding biofuels and biofeedstocks for the chemical industry are presented. Routes based on first-generation biomass (bioethanol and biodiesel) and second-generation biomass (non-food-biomass, lignocellulose) are discussed, with emphasis placed on synthetic gas chemistry (C₁-chemistry) originating from biomass. Also, carbon dioxide as a potential future carbon source is considered. Hydrogenation of carbon dioxide to methanol is an enticing option (methanol economy). However, the required hydrogen must come from renewable resources, such as sun- or wind-derived electricity, photochemistry, or direct photocatalytic splitting of water. Many options exist, providing a great challenge to research and development. Fossil energy raw materials will not disappear overnight, but research and development for substituting and replacing fossil raw materials must be carried out to have the right technology available when it is needed.

In his book Methanol - Chemie- und Energierohstoff [1], published in 1986, Friedrich Asinger already expressed his concern for the excessive exploitation of the valuable raw materials of crude oil and natural gas. He saw a “methanol economy” as the only visionary way out of this situation: “If hydrogen were cheaply available, this readily optainable pure, sulphur-free carbonic acid easily could serve as the starting point for the synthesis of methanol.” And “If fossil raw material sources one day become increasingly short in supply and more expensive, or even totally exhausted... there remains apart from biomass only carbonic acid as the source of raw material for the organic chemical industry”. In methanol, Asinger saw a chemical raw material that could spare the limited crude oil and natural gas resources. Apart from its importance as a chemical raw material, however, methanol could be of greatest importance as an energy carrier. Methanol itself or hydrocarbon derivatives thereof (fuels, olefins, etc.) could serve as a source of energy that can be easily stored and transported. At that time, Asinger evidently saw no danger of a shortage of carbon as a raw material.

Methanol can be generated from a wide range of carbon and hydrogen sources. Currently, large-scale production is dominated by the conversion of fossil resources, mainly natural gas and coal, to carbon monoxide and hydrogen (synthesis gas) as the intermediate for catalytic methanol synthesis. Although they are not yet economically competitive, more ecologically friendly processes have been attempted using regenerative carbon and hydrogen sources such as biomass, (recycled) CO₂, and hydrogen from electrolysis using regenerative power sources.

Methanol (also known as CH₃OH, methyl alcohol, hydroxymethane, wood alcohol, or carbinol) is a widely used basic raw material. It is a colorless neutral polar liquid that can be mixed with water and most other organic solvents in any ratio. It acts, owed to its polarity, as a solvent for many inorganic salts. The flammability of methanol (flash point 12.2 °C, ignition temperature 470 °C) can cause safety problems. For this reason, there exist many international guidelines for safe handling, explosion protection, and electrical equipment to handle methanol. Methanol also is a substance of high toxicity that is rapidly and almost completely adsorbed orally (via the gastrointestinal tract), by inhalation, or through the skin.

Oil and gas are raw materials—the availability of which is prognosticated to run short in the near future. The peak oil discussion is an example generally perceived as proof of this development to come.

Methanol is one of the most important intermediates in the chemical industry. The applications of methanol are versatile, ranging from feedstock for the production of specialty chemicals, polymers, and pharmaceuticals to energy applications such as the production of fuel additives or direct fuel blending. Considering a market price of approximately $450 per ton, methanol compares well with other liquid fuels, based on the costs per energy content

Energy sources in the future are a widely discussed topic, and many statements have been published recently by scientific societies and organisations. However, in most cases, an overall view on the topics of energy, fuels, raw materials, and climate is missing and only little attention is paid to the recycling of CO₂ for use as a raw material (e.g. for the synthesis of methanol), whereas much more emphasis is placed on carbon capture and storage [1]. Future energy systems will rely more and more on renewable energy (RE), such as wind, solar power, and biomass.