What is holding back renewable sources of energy like solar and wind? Arguments have been made that it is too expensive, or that infrastructure networks for generating energy in this way have not yet reached a commercial scale. I would argue, however, that the main hindrance to widespread adoption is its intermittency; the fact that there are seasonal and even daily fluctuations in wind and sunlight availability. For instance, whereas energy from wind turbines generated an average of 25% of the UK’s energy makeup in 2020, this fell to 7% during the month of September this year.[1] At its heart, this is an issue of supply and demand; there may be insufficient renewable-energy supply to meet demand at certain times and too much supply at others. In this article, a case will be made for hydrogen as a resource to manage these intermittency issues and enable renewables to act as a truly effective lever in shaping countries’ and companies’ trajectories to net zero. 

Firstly, it is important to assess why intermittency is important, which links to examining its costs. When the power output of wind turbines, for example, is too high and there is insufficient demand for this energy, these turbine operators need to discard of this energy. Over 8.7 terawatt hours of electricity has been disposed of in this way by wind farm owners in the UK over the last decade, and what’s more is that the government needs to pay these wind operators to do so. [2] Over £650m in so-called constraint payments have been paid for turbine owners to discard this energy , a bill that is footed by consumers of electricity through the Balancing Services use of Systems scheme. [3] Thus, the inability to store excess energy generated by wind is costing consumers and leading to emissions-free energy being disposed of entirely. 

Costs can also rise for consumers due to certain regions’ rising reliance on renewable sources, which drives up electricity prices when winds stop blowing, for instance. As gales in the North Sea grew less intense, so did the proportion of the UK’s energy makeup generated by wind decline by more than 70% in September 2021.[4] Since such a non-negligible proportion of the UK’s energy requirements were met through wind in 2020, the reduction in supply of this type of energy (with demand remaining relatively unchanged) drove up prices. So extreme was this volatility that in the space of one seven-hour period, the cost of electricity in the UK burgeoned ten fold to a record of £2,300 per megawatt-hour. [5] Partially due to such vicissitudes, Prime Minister Boris Johnson needed to strike a deal with Qatar to redirect liquefied-natural-gas cargoes to the UK in order to meet the country’s energy demand. Thus, the fact that the unreliability of renewables promotes a reversion to fossil fuels may limit the rate of investment in the sector and countries’ willingness to grow reliant on these sources of energy. 

However, there exist various solutions for storing surplus energy generated by wind and solar, and then releasing it when demand arises. Such methods would limit and potentially curtail the incidence of such consumer-harming price spikes. 

The most popularised option may be the use of lithium-ion batteries. When power plants are peaking in the power they generate, they can divert energy to be stored in these batteries. However, a key limitation to their use is that the scale of battery storage which would be required for grid stability is arguably not economically feasible. Indeed, according to an estimate by the Massachusetts Institute of Technology, over $2.5 tn dollars of investment would be required to ensure the availability of sufficient battery storage for grid stability in the US. [6]

Another option is hydrologic storage, whereby surplus electricity is used to pump up water into reservoirs. When energy is needed, water is then released to flow downhill, power turbines, and generate electricity. This method has reached notable scale in the United States, in particular, with over 1460 conventional reservoirs being utilised. Nevertheless, the societal costs of constructing the dams which are necessary for some of these reservoir systems may make them politically unfeasible. The construction of the Three Gorges Dam in China, for instance, resulted in the displacement of approximately 1.3 million individuals as the valleys behind the dam were flooded during construction. [7]

So, we reach hydrogen. The idea would be that when electricity is generated from solar and wind, it is used to electrolyse water, which would split it into hydrogen and oxygen. The hydrogen could then be used in fuel cells, whereby the chemical energy stored in the hydrogen molecules is used to power an electric motor. In fact, said fuel-cell systems are twice as efficient as the internal combustion engines which are found in most automobiles today. 

Another benefit of the fuel is its versatility. It can already be used as a fuel in transportation and for generating heat in particular. The element is also suitable for both long and short-term storage of electricity. 

What’s more is that the energy density of hydrogen, a measure of the amount of energy stored in a material per given unit of volume, is particularly high. This metric reaches an impressive 120 megajoules per kilogram, almost three times as high as diesel or gasoline. [8]

However, transporting the fuel is notably arduous. Due to its low density in its gaseous state, hydrogen needs to be cooled down below its boiling point of 253 degrees celsius for sufficient volumes to be transported. This process consumes vast amounts of energy and thus generates significant costs, potentially explaining why only a handful of liquefied-hydrogen-carrying ships have been developed globally (the most well known arguably being Shell’s Suiso Frontier). As a result, hydrogen may need to be generated and stored by electrolysers locally in order for its use to be cost effective. 

Hence, there exist a number of potentially viable solutions for addressing the intermittency issues linked with renewable sources of energy. Hydrogen, while having its drawbacks, does appear to be the most promising solution. Although it has been estimated that as high as 15% of global carbon-dioxide emissions can be mitigated through technologies relying on this so-called clean hydrogen, it  is still uncertain whether green-hydrogen systems can scale sufficiently swiftly to act as a truly meaningful lever in aiding the meeting of 2050 net-zero aims. [9] 

References: 

[1] https://fortune.com/2021/09/16/the-u-k-went-all-in-on-wind-power-never-imaging-it-would-one-day-stop-blowing/#:~:text=The%20situation%20is%20especially%20acute,generated%20on%20average%20across%202020

[2] https://www.power-technology.com/features/constraint-payments-rewarding-wind-farms-for-switching-off/

[3]https://www.power-technology.com/features/constraint-payments-rewarding-wind-farms-for-switching-off/

[4] https://fortune.com/2021/09/10/europe-net-zero-energy-bills-nord-stream-2-russia/

[5] https://fortune.com/2021/09/10/europe-net-zero-energy-bills-nord-stream-2-russia/

[6] https://www.technologyreview.com/2018/07/27/141282/the-25-trillion-reason-we-cant-rely-on-batteries-to-clean-up-the-grid/

[7] https://www.reuters.com/article/us-china-threegorges-idUSBRE87L0ZW20120822 

[8] https://rmi.org/run-on-less-with-hydrogen-fuel-cells#:~:text=Another%20advantage%20is%20hydrogen’s%20energy,more%20than%20diesel%20or%20gasoline

[9] https://www.goldmansachs.com/insights/pages/infographics/carbonomics/index.html

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