Week 2.8 - Potential of Sustainable Energy Sources

Hi everybody!

I hope that you have learned to roughly estimate the potential of the most important renewable energy sources this week.

Let’s go a little bit further and see how much sustainable energy is available and should be installed on a global scale .

Most of our used energy is directly or indirectly powered by the sun.

`in addition the earth itself can provide us with sustainable energy by the use of geothermal energy.

To put these energy sources in perspective we will show the potential of all them in reference to the total global power demand of the world of has a 16 TW.

This global power demand includes energy used for heating, transportation and industry, so it’s not only electricity.

The power demand is derived from an averaged global energy consumption,

Now, using the information from the International Energy Agency we will show the recoverable power of the energy sources we have discussed in the previous videos.

Note that because this is recoverable power, a conversion factor is already applied in these numbers.

Let’s start with Wind energy it has a potential between 25-75 TW easily enough to provide the entire world with sustainable energy.

But we have learned that wind energy has a low capacity factor because of seasonal and weather changes so we also need a baseload.

The use of ocean thermal energy shortly mentioned earlier can provide a part of that with a contribution of 3-11 TW, if the technology is fully developed.

Bioenergy has a potential of 2 to 6 TW and can contribute to a sustainable energy future the world -- if -- it does not significantly compete with food crops.

Hydropower is already providing a big portion of our world's energy need with 1.2 TW, but has limited room to grow further.

Its global potential is only 3 times that of the current installed capacity .

Geothermal energywavepower and tidal energy can also provide a substantial portion of our needs.

Maybe the potential of these energy sources shown here is smaller than you expected.

Luckily we still have one more card to play: Solar Energy.

If we would cover the entire land surface of planet earth with combined solar PV and heat systems ~ which of course is not realistic ~ we arrive at approximately 23.000 TW, a power potential far greater than we'll ever need.

Nevertheless, in the coming weeks we will discuss that not only one renewable source is the answer to our energy problems.

Every sustainable energy source has its advantages and disadvantages.

To further look into our renewable future we will evaluate the surface power density of all the sources we have treated.

Although the earth is very big on a human scale, it is essential to look at the power density per unit area of our sources to get an idea how much land is needed.

This table shows a range of densities that represent an average power density of all locations on earth and in is also averaged over time.

This means that the units do not need an extra multiplication with a conversion factor or capacity factor.

In addition We don’t take into account that some energy sources are not storable or peak demand on the grid.

For hydropower there is a potential of 8 to 10 W per square meter of reservoir area and 0.1- 0.2 for the water catchment area.

Wind is ranged for land and offshore installations.

For solar we took a moderate average insolation of 4 kwh/day/m2 and an moderate efficiency of 15% to include free space between solar panels.

For biopower we took a range from 0.1 to 0.3 W/m2 to include the most crops that can be used for energy generation.

Note that wave power has a range of 20-30 KW per meter and not per square meter because the energy in a wave can only be harvested once, perpendicular to the direction it is moving.

By now you must be wondering how much area is needed to power a substantial amount of energy with these renewable sources.

A prediction is made for the electricity power demand in 2040 which is equal to 4.2 TW.

Note, this is not the total energy demand, it is only the electricity power demand.

On this map I’ll show you an estimation of the total area that is required per renewable energy source - to deliver this power.

Note that the placement on the map is done randomly- so the calculations are not location dependent.

The only thing we have done, is divide the global power demand of 2040 by the power density of every energy source.

The recoverable global potential of hydropower is not fully sufficient to meet this demand.

This is caused by a lack of locations which have sufficient height difference.

But, in case -there would be enough suitable area - it will take a total reservoir surface of - 420 thousand square kilometers and a catchment area of 21 million square kilometres to provide 4.2 TW.

It is safe to say that this would be almost impossible to achieve.

For wind power we need an area of 1.68 million square kilometres, comparable to the size of a country as turkey.

For Solar PV the required area is moderate: only 140 thousand square kilometres.

Bioenergy could have the potential to fully provide us with electricity, but it will need 20 million square kilometers.

This is 13% of all the land on the world and is already more than is used for agriculture.

If Geothermal energy would have the potential to provide 4.2 TW ~ which it doesn’t ~ it would require an area which is bigger than the earth surface .

What about Tidal.

There are not enough locations with a suitable tidal fluctuation to meet the electricity demand of 2040.

But if there would be enough suitable locations a tidal reservoir of 1.4 million kilometers would be required.

If we take the same assumption for wave energy - we would need to place 168 thousand kilometers.

This is about half the length of all the coastlines on earth.

All these numbers represent a back of the envelop calculation but still can be considered as reasonable indications for the potential of these energy sources.

It may also be clear by now that not a single energy source will meet our energy needs of the future, and that we have to combine these energy sources.

Considering the energy density and the power potential of wind and solar energy, it shouldn't surprise you that the majority of the plants are wind and solar farms.

This week, I provided you with simple tools to calculate the potential of various energy sources.

In the last weeks of this course - we will discuss the technology and system aspects of these renewable energy sources in more detail.

Now, I challenge you to do these calculations for your country.

I hope this exercise will provide you more insights in the challenges we are facing if we would like to become less dependent on fossil fuels.