Tag Archives: liquid metal

The end of coal/oil/nuclear/(most) gas power generation?!


 

Okay not quite yet, but this kind of blue-sky thinking is the answer to ending our insane reliance on using fuel (usually through combustion) to heat water which in turn turns turbines to generate electricity. Now wind (and wave/tidal when they are more commercially viable), hydro and other forms of direct turbine generation (like natural gas) and solar voltaic are realistic options in generating power for our future needs.

Coal-fired plants currently operate at about 31% efficiency – as in less than a third of the stored energy in the coal is converted to electricity – and that figure doesn’t acount for transmission losses.  Euractiv.com
Even if experimental coal gasification plants were to come online, they would still only  operate at around 50% efficiency. DOE

Some modern fossil fuel plants could operate at up to 48% efficiency already, but this is the maximum owing to the laws of thermodynamics. Nuclear cannot operate at more than 30-32% efficiency at present, though designs currently at the experimental stage could get closer to that of fossil-fuel  turbines Wiki, but again no higher because in both cases the temperatures involved prevent greater efficiency.
Now wind (30 to 59%) and solar (up to circa 30% and even 50% in the future)[ Livestrong ] efficiencies using current technologies don’t seem to compete in terms of energy conversion, but there is the added bonus that once the generating capacity is installed, the energy source is free and does not require a transport or massively industrialised infrastructure to supply it. Wave and tidal power, which are currently still in development, have the potential to be up to 99% efficient USAF  and 80% NWE respectively.
Of course the decommisioning costs of renewable turbines and PV arrays are negligible when compared with the clean-up costs for fossil fuel and nuclear power stations – it seems to be quite difficult to find out what the estimated costs of decommissioning defunct power stations might be, which suggests that it will be high – especially with coal ( and all the toxic chemicals that don’t get burned like mercury, uranium, thorium, arsenic and other heavy metals Wiki) poisoning the land and nuclear which produces 10000 metric tonnes of fuel waste per year worldwide, but also huge quantities of low-level radioactive waste (but still less than and less radioactive than coal fired power stations), for which there is still no reliable disposal method even after 60 odd years. Therefore, one can safely assume that the clean-up costs of decommissioning nuclear and fossil fuel plants woud run to (probably) hundreds of billions of dollars.
Step forward Donald Sadoway, Professor of Materials Chemistry at MIT giving a short talk  at TED on the new liquid metal batteries that he has developed with his students (video below).

For the more scientifically minded amongst you, here is the PDF link for Sadoway et al  (published January 2012) in the Journal of the American Chemical Society

One Magnesium-antimony (Mg-Sb) battery about the size of a 40ft shipping container has a capacity of 2MWh – about enough for 200 homes. The technology is scalable (so smaller batteries could be used for individual houses, offices, workshops) and it is capable of dealing with the high temperatures that are associated with electrical surges (from rapid charging over a [relatively] short period of time). The metals, as the description “liquid metal”  suggests are kept in a fluid state in order that the Magnesium can migrate down through the electrolyte when discharging (forming a MgSb alloy) and back up when charging (returning to ions), thus the battery has an operating temperature of around 700°C and is therefore only really practical for stationary use.

This battery which of course has no moving parts to wear or break or that need replacing, could spell the end of antiquated power generation – steam turbines (which coal, gas (mostly), oil and nuclear power stations all use) could be a thing of the past, using [relatively] common materials that are inexpensive, ( Sadoway et al [2012] give Antimony (Sb) = $7/kg and Magnesium (Mg) = $5.15/kg ). It is worth noting that there are massive discrepancies in available data for price of the minerals used in these batteries, but nonetheless it is apparent that their cost and availability are not in question.  Indeed, they are very common and readily available.  Lawmakers ought to start to take the remediation and clean-up costs in mind when considering commissioning new power stations, because then they would be far more likely to opt for batteries such as this combined with a varied and multi faceted renewables portfolio.

Another great thing is that the batteries have low internal resistance,  so do not age nor do they decay through multiple cycles in the way that many modern batteries using rarer elements do, thus they have a good lifespan.

I really do see this as a fantastic breakthrough, this could be comparable to the invention of the internal combustion engine or the television for the massive way it could alter how we generate and use electricity. And it gives us the ability to store electrical potential for when it is needed, rather than ramping up the power at the ‘conventional’ power stations, as happens at the moment.

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