Food waste could store solar and wind energy, or there’s the obvious…
Saving up excess solar and wind energy for times when the sun is down or the air is still requires a storage device. Batteries get the most attention as a promising solution although pumped hydroelectric storage is currently used most often. Now researchers are advancing another potential approach using sugar alcohols—an abundant waste product of the food industry—mixed with carbon nanotubes.
Electricity generation from renewables has grown steadily over recent years, and the U.S. Energy Information Administration (EIA) expects this rise to continue. To keep up with this expansion, use of battery and flywheel energy storage has increased in the past five years, according to the EIA. These technologies take advantage of chemical and mechanical energy.
But storing energy as heat is another feasible option. Some scientists have been exploring sugar alcohols as a possible material for making thermal storage work, but this direction has some limitations. Researchers wanted to investigate how mixing carbon nanotubes with sugar alcohols might affect their energy storage properties.
The team analyzed what happened when carbon nanotubes of varying sizes were mixed with two types of sugar alcohols—erythritol and xylitol, both naturally occurring compounds in foods. Their findings showed that with one exception, heat transfer within a mixture decreased as the nanotube diameter decreased.
They also found that in general, higher density combinations led to better heat transfer. The researchers say these new insights could assist in the future design of sugar alcohol-based energy storage systems.
Of course breakthroughs like this bring me back to our original call for simple power storage with zero waste. Hydroelectric storage still offers the best way to effectively and efficiently store extra power with a high efficiency. The only downside to this approach is the size of the tanks needed, however given that these tanks could be stored anywhere so the size of the tanks should be a nonissue.
Also hydropower efficiency comes in at an amazing ~90%. Compare that to the best fossil fuel plants which come in at ~50% efficiency and it doesn’t make sense to find another storage medium until you can break the ~90% efficiency barrier. Of course, getting into the efficiency of pumping the liquid into the tank gets to be a little more complex and we won’t break into that one here, but this pdf does a good job of covering the basics.
Also sugar alcohols are a waste product today, but if demand rises then it is no longer a waste product.
The point being that we realistically have a viable solution that can be implemented today since it has so many benefits:
- Already has the needed infrastructure to implement
- Actual zero waste solution
- High efficiency return in non-peak times
- No potential for added cost due to higher demand for water
- No new types of maintenance needed — an important consideration
This is essentially the hydrogen powered car debate again, why hydrogen? There is no existing infrastructure to use, you are still burning something which like it or not is not helping the environment and it is great to talk about because the solution is so far away from being actually implementable that even the congressmen that gets the most donations from fossil fuel companies is all for the idea.
So with that little rant behind me, maybe we should make some noise around the situation.
Zhang, H., Rindt, C., Smeulders, D., & Nedea, S. (2016). Nanoscale Heat Transfer in Carbon Nanotubes – Sugar Alcohol Composite as Heat Storage Materials The Journal of Physical Chemistry C DOI: 10.1021/acs.jpcc.6b05466