This post is based on an article of mine, “Methanol electro fuel: A transport game changer” published in RenewEconomy on
12/3/13. It has been expanded to
include more discussion on other renewable, low impact fuels and the extraction
of CO2 from air and water. Briefly:
The renewable, low impact fuels described in this post can be produced in sufficient quantities to replace all fossil fuel requirements using commercially proven processes. All these renewable products are low impact because, unlike many bio-fuels, their production doesn’t require the diversion of land from food production, or damage to the environment. With the exception of hydrogen they could all be handled using existing gasoline, diesel or LPG infrastructure. Ammonia and methanol can replace LPG or gasoline after minor engine adjustments.
These renewable fuels are game changers. They provide an essential part of any credible plan for 100% renewable transport. As a result we don’t have to choose between 100% renewable transport vs destroying the economy, starving the poor or forgoing overseas travel.
Renewable hydrogen, methanol and ammonia can also be used to convert the production of a wide range of metals and chemicals to 100% renewable.
1. Renewable because it is produced from nothing more than renewable geothermal electricity, water and geothermal CO2.
2. Low impact because, unlike many bio-fuels, its production doesn’t require the diversion of food producing land or damage to the environment. Diversion of land to the production of bio-fuels is already causing starvation of people in some countries as well as damage to the environment. All renewable methanol requires is enough land to produce the renewable electricity and the space required for a compact production plant.
3. Able to be produced in very large quantities. Any form of renewable electricity could be used and, if necessary, the CO2 could be extracted from seawater or air if more concentrated sources of CO2 are not available.*
4. Electro because it provides a way of converting electricity into a transportable fuel.
In addition, methanol can be used to produce other fuels such as gasoline and diesel. (Gasoline was produced from methanol at Motunui (NZ) for a number of years using the Mobil process. The plant could have been operated to produce diesel if required.)
Renewable methanol, gasoline and diesel are transport game changers:
1. They allow credible, easily understood plans to be developed for 100% renewable transport: Plans that:
a. Could be as simple as replacing fossil fuels with renewable fuels. (NOTE: Better plans will involve a mix of strategies – For example, where practical, it will usually be more cost effective to use electricity directly instead of converting it into electrofuels.)
b. Don’t depend on the replacement of the existing transport fleet.
c. Don’t depend on starving the poor or damaging the environment.
d. Don’t depend on forcing little old ladies to ride bicycles.
2. They free long term transport plans from the need to consider greenhouse emissions.
3. In addition to cleaning up transport, renewable fuels could also be used reduce emissions from a wide range of industries. For example, most of the 50 million tonnes of methanol produced from fossil fuels each year are used as feedstock for the production of a range of petrochemicals. These petrochemicals would become renewable if they are produced from renewable methanol. The range of products that could be produced competitively from methanol would increase dramatically once the use of fossil fuels becomes unacceptable.
Methanol is not the only useful electro product than can be produced from nothing more than electricity, air and water:
1. The Fischer-Tropsch Process provides another proven way to produce a range of renewable hydrocarbons (including lubricants and gasoline) from nothing more than CO2 plus renewable power and hydrogen.
2. Dirty hydrogen made using fossil fuels has a key role in the production of a wide range of chemicals. It can also replace fossil carbon in the production of metals such as steel. The production of renewable hydrogen using electrolysis is the first stage of the Icelandic process for producing renewable methanol.
3. Dirty ammonia is produced by reacting dirty hydrogen with nitrogen from the air. Renewable ammonia can be produced by simply replacing dirty hydrogen with renewable hydrogen. Liquid ammonia can be transported and used as a fuel in a similar way to LPG 83% of the predicted world 2012 production of 198 million tonnes will be used in fertilizers. The remainder is used for things like the production of explosives, nitrogen containing chemicals, disinfectants and refrigerants.
The processes outlined above are not the only possibilities for producing renewable, low impact fossil carbon replacements in substantial quantities. Some of these, like this proposal for a salt water based algae plant at Whyalla may take their energy directly from the sun. Others may involve different routes for converting renewable power to fossil fuel replacement. It is certainly an area of active research.
*Recovering CO2 from Seawater or Air:
Numerous investigations of the recovery of CO2 from seawater or air have been conducted. For example, the
navy investigated the use of electrolysis for the recovery of
CO2 and H2 from seawater. This was
part of an investigation into the production of jet fuel using nothing more
than nuclear power, and seawater. Other
links talk about recovering
CO2 from air, comparison of recovery
of CO2 from air and water and the use of
waste heat to reduce the cost of recovering CO2 from scrubber chemicals. All that can be concluded at this stage is
that the production of renewable fuels from CO2 will be more expensive once the
supplies of high CO2 concentration sources have all been taken. Renewables that do not require CO2 may become
more competitive once this has happened.
and NZ commercial production stories put together mean that we don’t have to
choose between 100% renewable transport vs destroying the economy, starving the
poor or forgoing overseas travel. Iceland
Hydrogen has a role in the production of a wide range of chemicals. It also has a role in some of the greener ways of making metals such as steel.
Most of current world production is dirty hydrogen produced from the reforming of fossil fuels. This reforming process releases carbon dioxide to atmosphere. Less than 4% of current world production is renewable hydrogen produced by the electrolysis of water using renewable electricity.
While hydrogen is widely touted as the transport fuel of the future it comes with a number of serious limitations:
1. The established hydrogen storage technologies are limited to storage at very cold temperatures (-253 deg C) or high pressures (3500 to 7000 kPa). Neither is very practical for most transport purposes.
2. Hydrogen has lower energy densities compared with conventional fossil fuels. Even at 6900 kPa a litre of hydrogen has only 14% of the energy in a litre of Jet A fuel. (26% for liquid hydrogen) Specific energy per kg is much better @ 330%. (However, this figure does not take account of the weight of high pressure storage tanks.)
3. It is far more energy efficient to use renewable electricity directly for transport compared with renewable hydrogen. Even if the hydrogen is used in fuel cells, overall efficiency is likely to be less than 50%.
Methanol is used on a large scale (about 37 million tonnes per year) as a raw material for the production of numerous chemical products and materials. Methanol has the potential to be part of a wider range of chemicals if the use of fossil carbon ceases to be an option. At present, the bulk of methanol production starts with the conversion of methane to a mixture of hydrogen and carbon monoxide. This mixture is then converted to dirty methanol.
Methanol can be used as a transport fuel. Due to its high octane rating methanol can be used in internal combustion engines and gas turbines. Pure methanol is used as a racing fuel because it allows compression ratios as high as 15:1 to be used.
Methanol is a liquid under normal conditions, allowing it to be stored, transported and dispensed easily, much like gasoline. Its energy density is 47% by volume compared with Jet A fuel (46% by weight)
Ammonia is produced by reacting nitrogen from the air with hydrogen. Most of the world production is based on dirty hydrogen. A limited amount of renewable ammonia has been (is?) produced in Iceland.
Because of its many uses, ammonia is a major inorganic chemical. There are numerous large-scale ammonia production plants worldwide, producing a total of 131million metric tons of ammonia in 2010. About 80% of the ammonia produced is used for fertilizing agricultural crops. Ammonia is also used for the production of plastics, fibers, explosives, and intermediates for dyes and pharmaceuticals.
Ammonia can be used as a transport fuel in internal combustion engines and gas turbines with only minor engine modifications. (It needs about 5% biodiesel in the mix for diesel engines.) Ammonia used as a fuel can be stored and handled in a similar way to LPG.
Ammonia has lower energy densities compared with conventional fossil fuels. Its energy density is only 35% by volume compared with Jet A fuel. (43% by weight.)
D: Cost Comparisons:No clear cost comparisons were found. The Iceland experience with renewable methanol and ammonia as well as the NZ experience with the conversion of methanol to gasoline suggests that at least some renewable fuels will be competitive (or close to competitive) with fossil fuels if a supply of low cost renewable power is availa