- Category: Infrastructure
- Published: Monday, 08 November 2010 00:55
- Written by H2O
- Hits: 2378
In September 2010 the installed capacity of wind power in the UK was over 5 GigaWatts (number taken from renewableUK energy website: http://www.bwea.com/statistics/).
However, much of the energy generated by wind power fails to be utilised. The issue behind this waste is two-fold: an inadequate connection to the National Grid and high energy production when demand is low.
Due to the National Grid’s centralised nature it is not yet fully optimised to receive large amounts of energy from remote sites (these tend to be the locations where most wind power comes from). However, this is a factor that is likely to be addressed in coming years as the need for renewable energy increases.
The second major problem that has been facing wind farms is that the power generation can be both intermittent and unpredictable. The obvious solution to this problem is to store the excess energy and save it until it is needed later. The less obvious part is which energy storage method to choose, as reflected in a statement made by the House of Lords Select Committee on Economic Affairs in their Fourth Report, November 2008:
"A breakthrough in cost-effective electricity storage technology would help solve the problem of intermittency and remove a major stumbling block to wider use of renewable energy in the longer term. However, no evidence we received persuaded us that advances in storage technology would become available in time materially to affect the UK's generating requirements up to 2020. We recommend that the Government should as a matter of urgency encourage more research, development and demonstration in energy storage technologies."
It is interesting to note how accurately this statement reflects the current status quo. The only large-scale storage of energy that is presently being performed is through elevated reservoirs, such as Festiniog and Dinorwig in North Wales. Water is pumped from the lower reservoir to the higher reservoir when surplus energy is being generated. When the energy is later required, the water is then released back to the lower reservoir through a series of turbines to recover some of the power. This method is very primitive, costly and difficult to facilitate: you have to have the correct geographical aspects (in this situation 2 lakes, one higher than the other), plenty of money and be close to the original energy source.
The next commonly proposed option is the use of batteries, but this idea is misleading from the very beginning. Yes, the energy will be stored cleanly and will instantly be on tap when required, but at the same time you have to consider where the batteries came from in the first place. They are full of unpleasant chemicals which have to be mined and processed. They are dependent on finite resources such as lithium and this again makes them prohibitively expensive. Add to that the disposal costs and they are a complete non-contender.
Finally you have the underdog: hydrogen. Probably the most misunderstood energy storage medium that receives little consideration. For many, the word hydrogen conjures up little more than images of a blimp catching fire, but the science behind this technology is incredibly sound. During periods of surplus energy generation, an electrolyser can be used to split water into oxygen and hydrogen. The hydrogen is then stored in a pressurised container until it is needed. When the energy is later required, the hydrogen is passed back through a fuel cell to create both water and electricity.
So, the question you’re asking now is, why aren’t we using this technology? Until recently, electrolysers and fuel cells were items consigned purely to the science lab. This made them prohibitively expensive and unappealing to energy companies. However, recent interest from the automotive industry has kick-started a whole new wave of hydrogen commercialisation and research. The car manufacturers need this technology to work so that they can reduce vehicle emissions to meet future targets. This has led to improved efficiencies, production line scale-ups and innovation. Although hydrogen technology is not yet mass-market, it is beginning to head in that direction. This has significantly improved the economic viability of connecting a wind farm to a hydrogen energy storage system. Coupled to that are the additional advantages that hydrogen has to offer, which are:
• On-site generation
• No geographic requirements
• No harmful emissions
Indeed, the House of Lords may see a marked improvement in energy storage mechanisms well before their perceived target of 2020.