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12.56

Energy Storage Demand in a Sustainable World

The global transition to renewable energy production is in progress. Last year, 2015, more renewable power capacity, like solar and wind power, was installed as conventional capacity like coal and nuclear. Beside this nice development, there is a weak spot, the installed solar and wind capacity produce only when the sun is shining or the wind is blowing. For a full change to an emission free world, we need energy storage.

How big is the storage demand on a global scale, this is hard to guess, because it depends on a lot of assumptions. I will try to make a good guess within this post.

The Global "Energiewende" 

I will not describe the "Energiewende" (change of the energy system) in Germany, I will focus on the global change. This makes sense, because we have to change the energy system on the global scale to stopp the carbon problem and limit the exhaustion of the scare fossile fuels. 

The strong growth of PV installations, about 70 GW are expected for 2016, continues the long term trend of constant fast growing installations over the last decades. 

This trend will change the energy system as we know it today within two decades, to understand this lets look into the near history.

Growth of the energy consumption and the installed renewable energy production.
Consider the logarithmic axis of the installed power. Data source BP 
The first thing is, the electric power demand has a constant annual global growth of 3%. The installation of wind and solar power combined grows every year with 22%. The result will be, that somewhere around 2025, more fluctuating renewable energy is installed as conventional power plants. 

But be careful, the produced energy of wind and sun will still not match the demand, because they only produce energy when sunlight or wind is available. Resulting in the green line, which represents the mean renewable power generation. This line hits around 2030 the demand.

The result is, the next century will be dominated by the installation of storage to match the flucuating production at any time with the global demand.

Influence to the Storage Demand

The main impact for the storage demand has the electric grid infrastructure. The reason is, that the grid is the most efficient way to transport the electric power from the source to the customer. Is the sun shining in the southern part of a country, it is efficient to bring the energy to the cloudy northern part. And similar, if the northern part has a lot of wind during the night it makes sense to bring the energy with the same grid to the customers in the southern part.

This results in a competition between grid and storage.

To find the economic optimum between power grid size and storage is complex
Theoretical, it would be possible, to span a global grid around the globe and connect this grid with all solar power plants. This would result in a perfect 24 hour solar power supply without any energy storage at all because the sun shines always at some places on our earth.

The main problem seem the high price of such a grid and the energy loss in the power line. The other extreme case is a power storage at home with a seasonal capacity (only necessary in the northern region) of 1000 kWh for every person in the house. Then we can go off grid, sufficient PV on the rooftop assumed. The price for the batteries may reach a million dollars, not affordable.

If we dive into detailed computer simulations as done by J. Tambke und L. Bremen [1] we learn, that a country like Germany needs a storage capacity of seven days after a complete conversion to wind and solar has happend and there is a perfect power grid, often called a copper plate. 

Expanding the area of the perfect grid connection to an area like Europe only two days of storage is necessary. If we are optimistic and assume a perfect grid of this semi continental scale we need only a storage capacity of two days.

Further Chances to Optimize

Beside the grid, another chance to minimise the storage demand is the so called smart grid. Whenever possible, a energy consuming element in the grid goes offline if the power price is high or goes online if the price is low.

We dont know the exact possible amount of energy demand that can be shifted to other times but a optimistic guess might be, that 50% of the demand can be shifted in a way that the storage demand is halved.

Asuming this, we need only one day of storage if a smart grid and a comtinent size grid is available.

Adding up the Numbers

The energy consumption in the world in the year 2030 will be around 4,000 GW. To store this energy over one day, we need a 24h storage system with a capacity of 96,000 GWh. Keep in mind, the Gigafactory of Elon Musk may produce 100 GWh per year. If all the storage is used for the global Energiewende, the production for this demand needs about 1000 years.

But be careful, other solutions may be available.  The energy stored in the lakes of Norway contain an astonishing amount of 80,000 GWh, although there is no pump, the stored volume can only be used once in a year and has to be refilled by natural perception.
Pumped hydro technology may be a good solution, especially the Gravity Storage system, a typical site can store about 8 GWh. We still need 10,000 Sites, but tis seems to be more within practical reach, than a bure battery solution.  


References






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04.02

The World powered by the Sun

Today, photovoltaic electricity is only a small fraction of the global electricity production. The volume seems to be one percent in the year 2015. If we do a very simple extrapolation and imagine, that all these PV modules were installed in 2014 and we continue this installation speed, than we need another 99 years, to have a 100% emission free PV world. But this is simply not the way the world goes round.
I will try to extrapolate the situation, based on data from the MIT report "The Future of Solar Energy" [1]

Analyse the past of Photovoltaic

If we wont to understand the future, it is very useful, to look into the past, not only to understand the development, but also to understand the error which occurred by predicting the future. 
The Energy Information Administration (EIA) and the International Energy Agency (IEA) predict since 10 years the global PV installations in a published outlook. The first outlook from 2006 predicted for the year 2030 a global installation of 100 GW. This volume was already matched in the year 2011, only five years after the report was published! Ok, one wrong shot can be excused.
In the year 2011, the EIA predicted 150 GW until 2020. Again a failure, already in 2014 we have reached 180 GW of solar. 
The MIT analysed all predictions and compiled them to a very nice picture:
Figure 1: Different predictions and the reality, source MIT [1] page 137
In the early time, the predictions of the IEA had an exponential growth, that is a good guess, because most of the time, new products grow in that type. The only problem was at that time, the growth factor was to small, for example see IEA 2008 prediction in figure 1. Today things have gone worse with the prediction from the IEA. Not only is the factor to small, the prediction includes a reduction of the production of PV itself. This seems hard to understand.(An in depth analysis was done by Christian Breyer, paper PDF)
Things go even more strange, when we look at the price predictions of PV. The EIA predicted the development of the PV price till the year 2030. It should be mentioned, that it is a very difficult task to predict a price of any product for more than 20 years. But this failure is very illuminating.
Figure 2: Price prediction by EIA IEO 2009 of PV and observed results. [1] page 137
The EIA IEO 2009 outlook predicted, that the capital cost of PV in the year 2030 will drop to 4$/W.
Actually, the price even for residential systems dropped to this value already in the year 2014. It should be noted, that the price for residential PV systems in Germany was at the same time at 2$/W.
The price for utility PV systems reached only two years after the report was published the predicted value for 2030, 4$/W. 
All this information should be available to the EIA today. It irritates me, why the EIA does not change the prediction about the deployment of PV although they can observe the rapid price drop obviously. (I am thankful for any helpful hint)

Is there enough material for a large roll out of PV 

One possible reason, to be pessimistic about the global roll out of PV might be the scare elements used in PV systems. Today almost all PV systems use Silicon to convert sunlight into electricity. The MIT analysed the production of different raw materials, essential for the production of SI-PV-modules. 
To set up a PV system we need concrete and steel to mount the panel in the direction of the sun. Glass, aluminium and plastic are necessary to protect the silicon cell, cooper and more plastic is necessary to transport the power away.
Figure 3: Commodity materials required for PV. [1] page 131
Today, all these commodity are produced in a volume, that no real bottle neck will occur. In figure 3, we can see, that the steel production of 9 days is sufficient, to mount all PV panels for 5% of the global electricity production, within half a year, the steel production is sufficient for a 100% conversion to PV.
The least available material in this consideration is glass. For a 100% PV world, we need the glass production of 20 years. But glass production is in no way a limiting factor. The necessary raw material is sand, an endless resource.
The solar cell itself consists of a silicon waver and some silver, are they rare?
Figure 4: The annual production and requirement for a solar future. [1] page 135
In figure 4 we see, that silver might get a little problem, because we need an amount of silver that is produced within 30 years. It should be mentioned that new technologies of production can reduce the necessary mass of silver very strong. Other elements, like Ga are only necessary if we would use GsAs cells in our PV systems what is not widely the case. 
We conclude, the raw material is no show stopper for a PV future.

My prediction of PV growth

Compiling all this information, I come to a quite different prediction than the IEA. My simple, but till today best guess is, that the exponential growth will continue, but at a lower rate. 
Figure 5: Long term trend of PV installation.
In figure 5 we see the global installation of PV shown as a black curve in this logarithmic plot. In the year 1992, we had only 100 MW of PV installed, ten years later, 2002 it was 1000 MW, Today it is about 200 000 MW!
Update to Figure 5 including the growing power demand, wind and the latest figures available 2016.
If the growth rate continues at 25%, as seen within the last three years, we will reach 100% PV not long after the year 2030. Remember, today we have a global power plant pool of 5300 000 MW, sufficient to power half the world. Even if we expect, that the future is fair to all people, we need "only" 10 000 000 MW to bring electricity in every home on this planet, long before 2050.  

One problem remains: Storage

Without an affordable storage system, PV can only bring electricity during sunny daytime. For a complete conversion, we need about 90 000 GWh of storage [2].
One solution for residential systems may be the power wall from Tesla, but I am not convinced, that this makes sense on a large scale. For large scale, I recommend the Gravity Storage!

References:

[1] The Future of Solar Energy, 2015 Massachusetts Institute of Technology, ISBN (978-0-928008-9-8)
[2] Elon Musk predicts (minute 18) during the presentation of the power wall 90 000 GWh of required storage. https://youtu.be/yKORsrlN-2k
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05.53
Germany is the country with the largest relative (4%) and absolute (27 GW) share of solar energy in the grid. The reason is not the nice sunny weather in Germany, the reason is a strong subsidies policy called EEG (Renewable Energy Law). It gives the producer of photovoltaic (PV) electricity a good, fixed price over 20 years. Did this really have an impact on the growth of photovoltaic installations?
German was leading the growth rate, now the world has changed!
At the end of the 90s, the growth of PV installations grow with a rate of about 30%. This is quite a lot. With the start of the EEG in 2000, the growth rate in Germany leap jumped to more than 100%. At the same time the rest of the world has even seen a decrease in the growth rate, down to 20%. During the last two years things have changed again. The World, without Germany, has now 2011 a growth rate of 80% in PV installations, while Germany has fallen back to 40%, half of the global speed.

Why this Change?

The reason for this change lays in the price of PV-systems. During the last decade, the price declined from somewhere above 5000 $/kW down to 1000 $/kW due to the strong market in Germany. This low price makes PV economical within most of the sunny countries like Italy or India. Most countries have about double the sun radiation during the year than Germany receives.  
It seems so, that the growth of the solar installations is now market driven and therefore sustainable. But be aware, what 80% growth means, within 11 years, if the trend continues, the world may have changed to a complete solar energy driven world. Today, only 0,4% of the electricity is from solar, but in 2023 it could be near to 100%!



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02.13
The global volume of installed photovoltaic installation is growing fast, this is a well known fact. But not so widely known is the exact growth rate, so I will give some figures for a deep insight.
Different countries are different, so have a look into different countries.
A incredible dynamic in the growth of PV-installations
Fifteen years ago, the USA was the leader in PV-installations. In the year 1996, Japan became the leader but in 2005 another change at the top happened, Germany, supporting PV with high subsidies, took the leadership. But the PV-market has a very high dynamic and in 2011 Italy installed already more PV-panels than Germany. This race is interesting, but not the core of the global chance in the PV market. Lets have a look at the growth rate itself:
The growth rate is growing with 3% per year!
If we plot the growth rate between two years, we find an astonishing plot. Beginning in the mid ninety's, the growth rate was about 20% per year. And sometimes I have the feeling, many people have adapted this and believe in a moderate growth of PV. The last 15 year show a very different picture. The growth rate itself was growing. And a simple linear approximation results in a slope of 2.9 percent points (absolute!) per year, resulting in an approximated growth of the PV installation 2011 compared to 2010 of 67% (the actual value was even higher with 76%)

Reasons for the PV Growth

This mind-blowing effect is not widely anticipated. The reason for this effect is not longer the high subsidies of German PV-installation, the reason is, more and more countries start installing PV at a very high rate, as the first graph shows. And the reason behind this is, that many countries have much more sun as Germany combined with the hard drop of PV-prices. This results in an unprecedented dynamic, higher market volume results in higher production rate, higher production volume results in lower prices due to a learning curve.
The learning curve tells us, if we double the production, the price will fall about 20%. The dropping price opens more markets, if the price is below the power price at the consumer, he will install PV soon. 
Where will this growth end, this is not clear, but I will write about that topic soon.

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