Alternative Energy

Land demand for solar power

Solar energy for Germany, Europe and the world

There is a picture in the solar scene (picture 1) that probably almost everyone knows, it shows how large the surface area is when the world is switched to solar energy. It was, as far as I know, published by Mrs. Nadine May for the first time in her diploma thesis at DLR [1]:

Figure 1: Space requirements for solar power plants, according to Nadine May [1]

This image is widely used and should be checked for correctness. First of all, Algeria is the country that contains the squares for the world and Europe, and Libya, the country which possibly receives the German solar power plants, are no more colonies.

The squares have an edge length of: world 254 km, Europe 110 km and Germany only 45 km.

How big is the energy consumption in the world?

The energy consumption of the world is constantly growing (see figure 2), so it is difficult to specify the energy requirement without a reference year. Currently the demand is over 30,000 TWh (30,000,000,000,000,000 kWh) using the further processed data from the International Energy Agency (IEA). I have considered transforming factors for certain energy forms (transportation, heating) into electricity.

Figure 2: Global energy demand for electricity, transport and all other forms of demand

This energy should be converted with solar cells (PV) into electricity. There are several factors to consider, the efficiency, the irradiation in the course of a year and the necessary storage of the energy for the night.

Solar cells made of silicon achieve an efficiency of around 20% and are currently the most economical method to generate large amounts of solar energy.

The irradiation is very different in different regions of the earth, in particular one must always distinguish between direct and global irradiation. For photovoltaics (PV) only the global irradiation plays a role. Therefore, only these radiation is considered.

Figure 3: Global radiation perpendicular to the ground (source: WEC [2])

The map shows that many areas have an annual irradiation capacity of 2000 kWh per year, in particular the Sahara, but also on other continents good locations can be found; only exception is Europe.

Necessary Land Area

The necessary areas of the solar cells can now be easily calculated. For the world, we need 30,000,000,000,000,000 kWh per year, since one square meter has an incidence of 2000 kWh which would theoretically be 15,000,000,000 m� or 15,000 km�.
Now the efficiency comes into play, since only 20% is converted into electricity, we need the fivefold area, that is 75,000 km�. However, one has to be able to build the cells and needs paths and additional areas for inverters and storage, which should double the space requirement. This is 150,000 km�.
The transport and storage of energy, which is absolutely necessary, since at night the sun doesn't shine, will consume another 25% of the energy, so we are at 200,000 km�.

This corresponds to a square of 448 km of edge length, roughly twice as large as in the drawing.

Fair World

Currently, only a few people consume a lot of energy and lots of people have little energy. I am convinced that in the long term all people want at least to reach the standard of living as in Germany. For this, an energy quantity of 15,000 kWh per year and per person would be necessary. There are some countries that already have a much higher energy requirement, but we hope that energy efficiency will also save some energy.

With a world population of 8 billion people, this will yield an annual energy demand of 120,000 TWh or 120,000,000,000,000,000 kWh, or four times the current demand. This would increase the area with solar cells to a square with an edge length of 1000 km (Fig. 4).

Figure 4: Supply the world completely with solar energy in the future

Furthermore, the area of ??one million square kilometers is still small compared to the Sahara, but a serious part of the solid surface of the earth. The world has about 15 million square kilometers of sunny deserts, which means about 1/15 of this area must be used in the future for solar cells to deliver enough energy.

Storage requirements

If it is assumed that the energy must be stored for at least one day, this requires a storage capacity of 330 TWh (330,000 GWh)
Compared: Germany has pumped storage with a capacity of 0.04 TWh.
If large Gravity Storage systems with 80 GWh capacity (500 m diameter) solves the problem, a considerable number of 4000 pieces would have to be built.

Using batteries from Elon Musks Gigafactory, the gigafactory produces at a planned capacity 50 GWh per year; over 6000 years of production or 400 Gigafactories for 15 years are required. This is to provide the capacity for the first time and we have to continue production because batteries must be replaced after 15 years.

Gigantic conversion

If the global conversion to solar energy succeeds, huge buildings in the form of gigantic solar fields will be necessary. Surely the roof surfaces are never enough. Furthermore, investments are in the order of magnitude of the global gross social product of one year ($ 80,000 billion). This sounds a lot, but it will help mankind to be sustainable. Especially when one considers that afterwards energy is produced clean, without CO2 and at a low cost.

I think: we can do it!

Sources:

[1] Eco-balance of a Solar ElectricityTransmission from North Africa to Europe, Diploma Thesis of Nadine May, Braunschweig, May 2005

[2] World Energy Resources Solar 2016, World Energy Council 2017

A 186 page paper going into details is from Jakobson et.al., 100% Clean and Renewable Wind, Water, and Sunlight (WWS) AllSector Energy Roadmaps for 139 Countries of the World

World Energy Congress 2016 in Istanbul

From 9th-13th October 2016, the World Congress on Energy was held in Istanbul. It was the 23rd Congress since 1923.

The topics of the congress were distributed over the entire energy area, including the oil and gas production and renewable energies. There were many important statesmen like Russian President Vladimir Putin and the Turkish President Recep Erdogan, including many other government members from different countries, including the visit of Israeli Energy Minister Yuval Steinitz, the first official meeting after six years frozen relations between Turkey and Israel.

Side by side, Putin and Erdogan at the conference in Istanbul

Vladimir Putin talk was about the importance of energy and the price of oil, a remark about a co-operation with OPEC during the speech has moved the oil price to rise by 2 $! He was the only statesmen, who included the words "exponential growth of solar energy".

The issue of energy just brings together not only scientists and engineers, but also politicians and diplomats. The global linking of energy distribution, especialy natural gas, plays an important role and Turkey was presented as a hub between Asia, Middle East and Europe and the Mediterranean.

The world's energy

All participants have concluded, that the energy transition towards renewable energy, particularly solar and wind, is on the way. However, the completeness and how fast that arives is controversial. While I am convinced that before the end of the next decade the significant change of the energy system has been completed, Marie-Jos� Nadeau, Chair, World Energy Council believes that in 2060 the share of renewable might reach only 50% of total energy production [1] ,

Marie-Jos� Nadeau, Chair, World Energy Council

This is understandable from the perspective of the energy industry. They trade with oil, coal and natural gas. Should the change take place quickly, the oil and the coal is not any longer requested by the market. The industry worries about stranded resources. This means the oil in the ground, on which the wealth of large companies and nations is based, may become worthless.

Key issues in the energy transition in the coming decades

The importance of the Paris Convention for the CO2 reduction was repeatedly stressed. Generally, however, many see only a shift from coal to natural gas, as is well known, natural gas produces half as much CO2 when it is converted into electricity than coal! This is due to a fact that a methane molecule consists of one carbon and four hydrogen atoms, but also to the better efficiency of gas power plants.

Key finding: the phenomenal rise of solar and wind energy will continue!

Power Turntable Turkey

At the conference in Turkey, the geo- (energy-) strategic role of  Turkey was stressed by Erdogan.

Important oil and gas pipelines connect large resources of Asia with European customers, more gas and oil pipelines are planned.

Strategic position of Turkey

Finally, the construction of a new gas pipeline connecting Russian and other Asian gas fields to Europe by crossing Turkey, were one reason why Putin, but also the President of Azerbaijan, Ilham Aliyev, showed up in Istanbul.

The Importance of Hydro-Power

It's a certain irony, the most important renewable energy in the global mix, providing at least 71% of all renewable energy is hydro-power, or 6.8% of global electric energy production, is a often forgotten big player.

The importance of hydro-power may lie in a combination of solar, wind and hydro-power. At the conference solar power as named a water saver, in the form that during the day the turbines are shut down at the dam resulting in increasing water level, during the night, with redoubled turbines, water can be used for power generation. Thus normal dams are important energy storage elements for the energy transition. ot to forget pumped hydro storage or even the new technique of Gravity Storage .

A nice photoshop picture used as advertising billboard in Istanbul

There are, at least in Africa and in South America, still many untapped hydropower "reserves". However, anyone was well aware that each dam has also an enormous impact on nature and very often engages in the habitats of people! Especially in India, the water of the rivers is sacred and thus hardly the construction of dams possible as mentioned by Richard M. Taylorlearned Chief Executive, International Hydropower Association.

Africa to get electricity

While the inhabitants of the Americas and Asia are almost completely supplied with power, in Africa there are still 600 million people without electricity. This means no light, no easy way to charge a mobile phone, no fridge and no welder.

The last day of the conference was therefore devoted to Africa. In Africa, here essentially black sub-Saharan Africa was meant, you have to think about the huge areas and the still sparsely populated countries. This makes the construction of a conventional electric grid network uneconomical and therefore solar energy stand-alone systems and microgrids are very important.

The forum "Talent and Capacity Building" moderated by Samir Ibrahim from Kenya, right Sanjit 'Bunker' Roy from India, next to Andreas Spiess, Solar Kiosk , from Germany.

The practical implementation requires some knowledge of electricity and solar energy. Bunker Roy helps the people with his Barefoot College to teach this to everyone. While he teaches women worldwide (Grandmothers) to practical issues of the use of solar energy, an impressive project!

Andreas Spiess tries with his, as he stressed, commercial solution of the solarkiosk promoting the dissemination of locally adapted use of solar energy in Africa.

The Exibition

Booth of Heindl Energy GmbH

The Heindl Energy GmbH has presented the "Gravity Storage" technology on its exhibition stand. Unfortunately, very few companies from Europe were represented at the fair. The booth was right next Aramco, the largest oil company in the world from Saudi Arabia. As far as I have observed, our stand had awakened almost more interest.

A 600 MW power plant on the water for emergency cases

There were of course many other interesting exhibition stands, I found the idea of ??"power ship" interesting, which is a ship with a complete power plant (up to 600MW), inclusive substation, which anchors in a port and supports the local power generation, after a natural disaster or for other reasons.

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