Geopolitics, the environment and cost make it a matter of urgency to phase out dependence on fossil fuels.
It is proposed that the metal magnesium (Mg) could play an important role in this.
Mg is abundant in nature, non-polluting and non-toxic. The metal is practically indestructible, safe and easy to transport and store.
When reacted with atmospheric oxygen, the amount of energy released is not much less than from an equal weight of hydrocarbon. If a Mg-air fuel cell can be developed, it should have an efficiency for electricity generation of about 90%, in contrast to hydrocarbons where the energy is only available in the form of heat with a maximum conversion efficiency of about 60%. The density of Mg is about twice that of hydrocarbons, Thus Mg is better than hydrocarbons for transporting and storing both in terms of weight and volume as well as safety.
The technology for producing the metal in quantity already exists. Sources of renewable energy have already been developed. Existing shipping and storage facilities can easily be found or adapted
Mg-air batteries, have already been developed, so it would only be a matter of improving and scaling up the manufacture to replace nearly all requirement for fossil fuel with something that is better all round.
There is a strong case for ceasing all further developments in fossil fuels, and directing all investment instead to building up an Mg energy system.
Many sources of renewable energy are in remote locations, which makes direct electrical transmission difficult and/or lossy. An alternative would be to have local Mg production plants and store the metal on site until it can be collected.
Most sources are also intermittent, so it would be better to produce Mg locally when there is an excess of energy rather than generate electricity and then store it somewhere else.
An extreme case of this, which would be of considerable economic and environmental advantage, would be to have a hydro-electric system that operates seasonally when the flow of water is sufficient, thus removing the need for water storage and the associated dam. The only reason these are normally needed is to store energy from the wet season to the dry. Generating Mg is doing this instead.
Many of the current major oil-producing counties are very economically dependent on oil and will be strongly affected when demand for oil disappears. Several of these countries happen to have extensive tropical deserts near coasts, so for them to build magnesium production could provide a useful alternative.
Because of the low cost of storage and relative ease of turning Mg into energy, it could have a useful role for stockpiling energy and for barter in global markets.
Hopefully it would also remove the economic justification for the further development of nuclear power.
Green technology for producing the metal is well established but will have a significant start up time, so it would not be able to exploit the more intermittent non-renewable sources. Currently the cost of Magnesium is about four times that of bunker fuel. This could be reduced by improved technology and automation.
The technology for turning the metal back into energy exists but not on a large scale.
Cost of Magnesium
Using a cost breakdown of Aluminium production as a guide to the likely he cost of production of magnesium, see:
https://www.researchgate.net/figure/Cost-breakdown-of-the-aluminium-produced_fig1_309143780
| Component of cost for Al | % of cost | For Magnesium | |
| Source material | Alumina | 23% | MgCl2 from sea water will be cheaper than Bauxite |
| Energy | Hydroelectric | 34% | Less, depending on using intermittent sources |
| Other raw materials | 14% | Potential to reduce by improved technology and automation | |
| Labour etc. | 29% | ||
We would be looking for a reduction of cost by a factor of four, or less if a fee is charged on the use of fossil fuels.
Links
Shipping batteries Could Mg-air batteries be built in shipping containers and used to power shipping?
https://en.wikipedia.org/wiki/Magnesium_battery#Primary_cells:
“A magnesium–air fuel cell has theoretical operating voltages of 3.1 V and energy densities of 6.8 kWh/kg. General Electric produced a magnesium-air fuel cell operating in neutral NaCl solution as early as the 1960s”.
There is a plentiful supply of salt water! But the reaction product is Magnesium hydroxide not oxide as in my calculations, meaning the weight gain per unit of electrical power is less favourable.
Related topics: