Here at the GreenAge we love renewable energy. There’s absolutely no doubt that it’s the way forward, not only for the UK but for the whole world.
That said, we think it’s important to understand how renewable energy works, and realise its limitations. Only then can we maximise its potential, and move forward with a cleaner energy system.
We’ve done a podcast on this topic, covering the intermittency issue as well as many other issues we’ll have to tackle. You can listen to it here, or scroll to the bottom of the article to watch it.
What is intermittency?
Without a doubt, the biggest problem with mainstream renewable energy is intermittency. Wind power is only generated when it’s windy, solar power is only generated when it’s sunny. This creates several fundamental issues.
We need some level of predictability with our energy generation, or we risk mass blackouts. On a windless day without any sun, we still need power.
At the opposite end of the spectrum, are the times when these forms of generation create more power than we’re able to handle. There are times at which the national grid, in its current state, cannot handle the energy we’re generating.
How does intermittency affect the grid?
So to understand how intermittency affects the grid, first we need to understand how the National Grid works.
The main problem is that in order to operate properly the National Grid has to work maintain a 50Hz frequency, and if it varies too much from that then there are big problems. It’s a demand and supply thing. If demand is up then supply needs to be high, if demand is low then we need to reduce the amount of energy going into the grid. That’s okay with controllable energy generation like gas, but is a problem for things like wind and solar.
Take, for example, wind turbines. If the wind is blowing like crazy but the demand is low, the frequency rises too high. If the demand is high but it’s a still day, the frequency of the grid falls too low and we begin to experience blackouts. These fluctuations caused by intermittency can, if not properly managed, can cause a lot of damage to the National Grid infrastructure, which would be extremely costly to repair.
How can we combat the problem of intermittency?
At the moment, we use subsidies like the above to prevent the grid overloading from intermittent sources at times of excess generation. We also rely on other, more easily controlled sources to work in tandem with our renewable energy generation. This can’t be a baseload plant like nuclear, it has to be something that we can turn on and off at short notice. In the UK, this is predominantly gas. One of the issues with renewable power is therefore that the more renewable infrastructure we build, the more gas (or similar) plants we have to construct in order to counter-balance.
So why don’t we put the extra energy into batteries? That would solve the intermittency issue, right? Well, theoretically yes, but the problem there is simple: technology simply isn’t there yet. We do have some battery storage, but nothing on the scale that we’d need. Developing new and better batteries will be the defining feature of 21st-century energy management. We need it, and we need it now.
Think we missed something? Do you have a different opinion?
Comment below to get your voice heard…
interesting article!! not something i’ve ever considered before!!
Excess generation doesn’t affect the FREQUENCY, it affects the POWER.
Also, you may wish to mention emerging technologies like GRAVITRICITY which aim to absorb excess power and release it during periods when demand exceeds supply.
FAO Harriette
I believe that I have a solution regarding intermittency, one which I cannot believe has not been given serious considered before.
Having had time to research following heart surgery, as a retired scientist I have been hugely disappointed by the lack of development of FCEV’s compared to the considerable commitment by both BEV manufacturers and the government department for Business and Energy Industrial Strategy. (BEIS)
The former, I can understand. There is already a substantial developing market, from Tesla to Leaf, for the ‘quick-fix’ opportunism which readily available electricity makes immediately possible. However, regardless of the inherent problems of range and refuelling times, the expansion of the BEV market pays no regard to the increasing demand on the National Grid. As ‘second’ short range domestic vehicles I can see that BEV’s have a realistic place, though I find the government expenditure on increasing infrastructure beyond domestic supply, seriously worrying. (probably less than 30% of British homes have ‘on-drive’ parking for charging and even those that do may find difficulty in accommodating the charging of two or more cars). The increased queuing at public recharging stations, with the possible volume of BEV’s before 2050, does not bear thinking about.
With only one ‘under-canopy’ refuelling opportunity alongside current fuels (Beaconsfield service station on the M40), a few other ‘stand -alone’ supplies, (try finding them!) the potential for hydrogen powered FCEV’s seems hopeless. If the government funding initiatives were re-directed to providing a hydrogen refuelling infrastructure, having studied maps of Britain I believe that about 150 strategically placed refuelling stations would provide an attractive workable solution. As demand grows, more stations in towns and cities could be extended alongside, and ultimately replacing, current fuel pumps, using the Beaconsfield model at existing refuelling stations.
Now for the important and most ‘elegant’ enabling proposal. The ‘Intermittency’ issue regarding wind power (and solar) potentially provides the solution to our electricity supply requirements with several attractive additional advantages:
1) We are one of the ‘windiest’ countries in Europe with a high central spine and the mostly reliable surrounding on-shore /off-shore wind potential for generating more additional electricity supply.
2) Given a considerable investment to increase the number of wind turbines with the PRIMARY PURPOSE of dissociating water using electrolysis to produce hydrogen, that same supply could be switched virtually instantaneously to supplement our proven fragile National Grid.
3) The double bonus of this commitment would enable the ultimate benefit of ‘flat-lining’ our full use of electricity supply and demand. Rather than selling cheap-rate night time electricity generated by thermal power stations, this currently under-used supply could be fully utilised by diverting it to produce and supplement the supply of hydrogen.
4) Should we achieve the goal of excess supply of hydrogen, it could be used to supplement our natural gas imports by up to 20%.
Unlike excess electricity, surplus hydrogen could be stored in historic mines.
While a grid or ‘highway ‘of hydrogen may be futuristic, it is no more so than roads, canals, railways, current gas supply and the national grid which have historically met our supply and distribution needs. Reducing costs of supply may also be achieved by on or near-site clusters of turbines where possible, for production of hydrogen at the point of end use..
While I am aware that battery charge times and efficiencies are constantly in development, particularly with the use of silicon anodes, so are more efficient technologies regarding hydrogen production using high temperatures and the use of polymer electrolyte membranes (PEM’s), The fact that the end-use of hydrogen is currently more expensive than electricity, the long term practicality, advantages and disadvantages, should be given balanced consideration. Electricity is still predominantly produced using fossil fuels. Hydrogen provides a zero carbon option which cannot be overlooked. We should not be swayed by the arrogant assertion of Leon Musk that “Fuel cells are incredibly dumb” and “mind bogglingly stupid” This is as short sighted as Einstein saying in 1932, “At no way in the future can I see the development or realisation of a nuclear weapon” or Bill Gates being once reportedly saying “640Kb is more memory than anyone will ever need on a personal computer.”
We are on the threshold of a ‘step change’ which will determine our carbon free future and we need to get the balance right. I for one would not wish to extend my 6 hour (min.) journey to my daughter in Scotland by more than another hour for the privilege of driving a Tesla, not least when I can see the considerable inherent advantages of the arguments for FCEV’s above.
I can provide source references from my research if required.