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Can we generate 100% of our energy from renewables?

Posted by Alex Barrett on 11 November 2016 at 11:46 am

In early May of 2016 Portugal covered all of its electricity demand for four days using only renewable sources, energy prices in Germany briefly turned negative, as renewables met almost all of the demand for a day, and the UK didn't use any coal fired power stations at all during several low demand periods [1]. This is great news for renewable energy, but how far are we from being able to generate all of our energy from renewables?

20% of global electricity from renewables

It is estimated that in 2013 an impressive 21.6% of the global electricity generation came from renewable sources [2, 3]. This looks set to increase in the future, but renewable energy remains a small fraction of our overall generating capacity. The brief periods of 100% renewable power seen in Europe will hopefully become more common, but how close are we to being able to retire our fossil fuels entirely?
If the world is to respond to climate change before it reaches dangerous levels then we have to implement sweeping reductions in our use of fossil fuels by 2050 [4]. In order to do this we will need to dramatically increase our renewable generating capacity.

There are already some parts of the world where 100% of energy is generated from renewable sources. What is it about these regions which makes them suited to the adoption of renewable energy? And how can this help the rest of the world?

Many small, isolated communities exist “off grid” and generate all of their electricity from wind and wave, but it is also possible for much larger areas of the world to be 100% renewable.

Hydroelectric at work

Iceland, Norway, Paraguay, Uruguay, Quebec, and the South Island of New Zealand all generate almost all of their electricity using renewable means [5, 6]. Unfortunately these areas are unusual in that they have large natural resources to tap. In almost all of these cases the vast majority of energy is generated by huge hydroelectricity projects, with a much smaller amount of wind and solar power being used to supplement this supply.

Some forms of renewable energy are better for large scale energy production than others. Demand for power changes throughout the day, but storing energy remains a challenge. Consequently we need enough generating capacity to meet the total demand at any given time. Base load power stations provide a continuous stream of energy, while other stations come on line at times of peak demand to supplement this. Wind and solar power are by their very nature intermittent and so are not reliable enough to meet all of our energy needs. We can instruct a conventional power station to burn more gas at peak times, but we cannot control when the wind will be strongest, or when sunny days will occur.

Hydroelectric stations provide sufficient control to provide this rapid response to changing electricity demand. Paraguay generates electricity from several large hydropower dams and is estimated to have a reserve of 56,000 MW. These stations produce more electricity than is consumed in Paraguay itself. This excess electricity does not go to waste. Paraguay is located in the centre of South America and is consequently in an excellent position to export large amounts of electricity to neighbouring countries. This reduces the need for fossil fuel use in those regions as well.

Iceland is in a similar position. It has several large rivers which have been developed into hydroelectric projects. It also has extensive geothermal energy from volcanic activity. Several other rivers would be suitable for hydropower, so Iceland could reliably generate more power than its population can use.

However unlike Paraguay it cannot export electricity as effectively. Iceland’s isolated position means that electricity largely has to be used locally, although plans for interconnectors are in development. This doesn’t mean that it can’t benefit the rest of the world. Energy intensive industry can be conducted in Iceland to take advantage of its cheap, clean power.

This gives us two ways that we can utilise areas with readily available renewable energy reserves. We can import electricity from them, and we can outsource our industry to regions which can cleanly support it.

Nuclear for base load?

It is likely that most of the world will never be 100% renewable. A large amount of power will always need to be generated locally. The proportion of electricity generation from renewables is increasing all the time, and developments in storage technologies may one day allow this to meet our energy needs. But for the time being we may still need to use nuclear power stations to provide much of our base load. The other option would be to continue to use fossil fuels, but offset greenhouse gas emissions through carbon capture.

Importing as much green energy as possible would be a much better option.

References

  1. The Guardian
  2. Energy Atlas
  3. US Energy Information Administration
  4. Intergovernmental Panel on Climate Change
  5. Wikipedia: 100% renewable energy
  6. Renew Economy: Iceland
  7. London School of Economics (Links to pdf)

Image credit: Wikimedia commons Yacyretá dam in Paraguay CC BY-SA 2.5

 

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Comments

1 comments - read them below or add one

dominator99

dominator99Comment left on: 30 November 2016 at 10:10 pm

"It is likely that most of the world will never be 100% renewable"

I do not agree with this statement!  The sun's energy reaching Earth alone is far in excess of our planet's needs. Excess electricity created by solar pv panels could be stored by converting water to hydrogen gas. The hydrogen that is converted to natural gas could be used to power gas fired power stations to generate electricity on demand.

Using hydrogen & carbon dioxide to produce methane (natural gas) seems the way forward as a means of 'storing electricity' on a global scale & also providing a renewable version of natural gas rather than its fossil fuel equivalent.

I believe Germany is trialing injecting hydrogen gas produced from excess solar pv electricity into its mains natural gas pipelines but this has limitations.

http://phys.org/news/2010-05-green-electricity-natural-gas.html

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