Optimum Wind2Solar ratio

What`s the optimum wind to solar ratio for Germany in order to generate equal ammounts of electricity on a weekly basis troughout the year? Let us see how thing turns out based on how wind and solar performed in 2017. The table below express wind and solar generation as a percentage releative to average weekly electricity generation (EWF = weekly energy factor).

A 75/25 ratio seems to be a good fit. This is also close to the current wind to solar ratio which is and have been around 70/30 for serval years. Under is a graphic representation on the wind and solar generation from 2011 to 2018.

Why solar Net Metering is economically unsustainable

1. The utility companies makes less money, but the cost of maintinging the grid is fixed. This means they have to increase the cost of electricity for those without solar panels.

2. When the fossil power plants have to reduce their output, the cost per kWh will increase.

3. If to many households install solar panels, overgeneration will become an issue. When the sun is shining, a solar rooftop system might produce 10 times as much power than the house itself consume.

In order for solar energy to become a viable solution, the cost pr kWh electricty will have to vary based on time of day, current weather, weather forecast, time of year and much more. Renewable energy will never work with a fixed price!

If you are one of those who think the utility companies is greedy, you are probably right. But if you are defending the net metering policy, I would advise you to educate yourself!

Lithium reserves - Do we have enough?

Fun Fact(s): Worlds lithium reserves/resource are estimated to be about kg (53 billion kg). In order to produce 1 kWh battery you need approximately 0,15kg lithium. Thats enough lithium to make 353.333.333.333 kWh = 353 TWh of batteries.

What can you do with 353 TWh worth of energy storage?
- Make 3,5 billion Tesla Model S with a 100kWh battery
- Power the worlds electricity grid to for 6 days.

How many solar panels to charge a Tesla?

If a Tesla last for 300.000km and have an average consumption of 0,2kWh/km, you will need 60.000kWh in total. Let us also assume you keep the car for 25 years which is also how long most solar panels is expected to last.


In sunny California (capacity factor of 25%) you will need 4 solar panels a 270Watt to produce 60.000kWh over the solar panels 25 year life span! The catch is that you will be limited to 12.000km a year and a maximum daily range of 50km. Great if you like to park the car in the garage during day, and enjoy a joyride in the evening!
In a less sunny place such as Germany you will need 8 solar panels. On the bright side, this result in twice as much energy on a sunny day meaning a daily range of up to 100km.

To be noted: Having solar panels exclusive for car charging is a stupid. All solar panels should be connected to the electricity grid so that electric cars can be charged up to 100% on sunny days. #loadshifting

Germany 2015 - Solar VS Wind

How much energy storage would Germany need if one hundred percent of the electricity was to be generated by only solar or wind? And how do solar and wind generation numbers compare at different times of year? Is there a chance they do “cancel each other out” in a way which could reduce the need for storage? Well, let`s see how it turns out based on the generation numbers from 2015 collected by strom-report.de!

Wind capacity: 38.000.000kW = 38.000MW = 38GW = 0,038TW
Wind peak: 32.600.000kW = 32.600MW = 32,6GW = 0,0326TW
Wind energy: 85.600.000.000kWh = 85.600.000MWh = 85.600GWh = 85,6*TWh
Wind capacity factor: 30% (based on national maximum peak generation)

Solar capacity: +39.000MW = 39GW = 0,039TW
Solar peak: 25.800.000kW = 25.800MW = 25,8GW = 0,0258TW
Solar energy: 36.800.000.000kWh = 36.800.000MWh = 36.800GWh = 36,8TWh
Solar capacity factor: 16,28% (based on national maximum peak generation)

- The annual energy generation for wind and solar is equal. Ewind = Esolar
- Energy consumption is equal every month
- No losses during charging/discharging


Table explained: The table is based on the solar and wind electricity generation data from Germany 2015 in order to figure out how much energy storage would be required. B3 = 43,7 = wind generation capacity factor in January 2015. C3 = Emf = monthly energy factor = 1,46 = energy produced compared to the average monthly production. A number above 1 means to much energy is generated and a number below 1 means to little energy have been generated. C15 = 1,96 = months of energy storage which is required if 100% of Germanys electricity consumption was to be generated from wind turbines. Column F, G shows how things turn out in a scenario where the annual generation is a 50/50 split between solar and wind.

As we can see the solar and wind production cancel each other out quite nicely and the energy storage requirement is reduced from 2/3 months to less than 1 month!

Now, let`s see how many GW of solar and wind Germany need to install if they were to be sole producers of electricity and annual electricity consumption is 576TWh. With a 50/50 split between solar and wind, both producing 288TWh a year we will need X terawatt of wind installed and Y terawatt solar installed:

2018-04-21 14_39_01-Germany 2015 - Solar VS Wind - Word.png

Since the capacity factor is calculated based on the nationwide maximum peak, the actual capacity installed need to be somewhat higher, about 128GW of wind and 300GW of solar.


Fun fact: On a day which is both sunny and windy, only 65GW out of 310GW can be used directly, a little more if electricity consumption in general is less during night. The rest need to be stored in some kind of battery or be wasted!

How much electricity per capita?

How much electricity do humanity consume today? How much electricity do we need in a fossil free future to maintain our way of life? And how will population growth and increased prosperity affect the global need for electricity?

Electricity consumption per capita  in a selected numbers of countries (Source: CIA 2016)
Iceland: 50.613kWh
Norway: 24.006kWh
Canada: 14.930kWh
USA: 12.071 kWh
Taiwan: 10.632kWh
Australia: 9742kWh
South Kora: 9720kWh
Singapore: 8160kWh
Russia 7481kWh
Japan: 7371kWh
Germany: 6602kWh
France: 6448kWh
Spain 4818kWh
United Kingdom: 4795kWh
China: 4310kWh
World average: 2674kWh
Iran: 2632kWh
Brazil: 2516 kWh
Thailand: 2404kWh
India: 1122kWh
Indonesia: 754kWh
Pakistan: 405kWh
Kenya: 162kWh
Congo: 114kWh
Niger: 64kWh
Chad: 16kWh

It seems like a electricity consumption of at least 5000kWh/per capita is needed in order to become a memeber of the industrialized world. That said, many industrialized countries can probably reduce their consumption significantly and still maintain a good quality of life. Unfortunately I`m afraid that what ever is gained will be leveled out because electrification of heating, industry and transport. Inefficient energy storage will also increase the need for generated electricity. My sugestion is that we should aim for a maximum annual electricity consumption per capita of 1kW⋅24h⋅365d = 8760kWh.

What to take into consideration:
- Prosperity: Have you ever seen aircon on a african mud hut?
- Natural gas for heating? This factor partly explain why for example Germany and the UK have low electricity consumption compared to many other western countires.
- Climate: The cold climate in Norway combined with low cost of electricity leads to high household electricty consumption.
- Housing: Old houses generaly need a lot of energy for heating compared to modern ones.
- Industry: Some countires have a lot of power hungry industry compared to others.
- Transport: Electrification of transport increase electricity consumption.

Fun fact: If 7,5 billion people was to consume 8760kWh annualy, the worlds electricity generation need to increase by a factor of 3! Luckily the worlds wide pupolation is expected to grow towards 12 billion!!!! *irony allert*

Biomass to electricity - A dead end?

Land area: 357.000km2
Agricultural land: 167.790km2 (47%)
Population: 82.670.000
2014 annual electricity consumption: 576TWh
2014 annual electricity generation: 614TWh

Biogas electricity 2014
Installed capacity: 4830MW
Electricity generated: 29.120.000 MWh (5% of 576TWh)
Area used 1.353.000Ha = 13.530km2 (8% of all agricultural land)
Areal energy density: 2152MWh/km2

As we can see you need alot of land planted in maize in order to generate a unite of electricity. One square kilometer of land gives you 2152MWh of electricity which compares to well over 100.000MWh for solar PV located in a region with a capcity factor of 12% . If all of Germanys agricultural land was to be planted in maize in order to produce electricity, it would still only generate 62,5% of Germanys annual electricity needs! Keep in mind that natural gas is widely used for heating and transport still runs on fossil energy, thus the electricity demand will probably increase in the future unless they are able to reduce electricity consumption elsewhere! 

Fun fact: If all arable land world wide (15.749.300km2) was used for bio elctrcity it would generate  34.000TWh or 4518kWh per world wide capita! (given a yield of 2152MWh/km2 )

- The machinery required for seeding and harvest consumes large amounts of fossil diesel.
- Maize needs nitrogen fertilizer which currently consumes natural gas during production.
- Maize fields are prone to soil erosion. Heavy machinery leads to soil compaction.
- The powerplants are mainly located in rural areas where the waste heat can`t be utilized.
- The installed MWel capacity is currently way too small to use biogas as a battery when the sun and wind is underperforming.

How biomass should be utilized:
- Biofuel (ideally liquid fuel)
- Bioplastic
- Biogas for industrial use
- Electricity production when the sun and wind generate less electricity than expected and other kinds of energy storage is close to be depleted! As it stands, Germanys biogas plants acts more like a baseload power supply.
- Or just leave the land alone and promote a more sustainable agricultural future!

YouTube video below: If this farm is able to produce enough biogas to run the 770kW generator continuously 24 hours a day, 365days a year, the areal energy density will be 3066MWh/km2.

Solar storage requierment - California

How many days/weeks/months of battery storage would you need if 100% of the electricity in California was to be produced by solar PV?

1. Monthly energy consumption is equal every month
2. No losses when charging/discharging the battery

Imperial Valley Solar - 200MW
2014 - 1,36 months of energy storage required (Cf = 28,57%)
2015 - 1,41 months of energy storage required (Cf = 30,74%)
2016 - 1,51 months of energy storage required (Cf = 30,62%)

California Valley Solar Ranch - 250MW Single axis
2014 - 1,75 months of energy storage
required (Cf = 31,25%)
2015 - 1,51 months of energy storage required (Cf= 31,42%)
2016 - 1,72 months of energy storage required (Cf= 31,04%)

Dessert Sunlight - 300MW Fixed
2014 - 0,79 months of energy storage
required (Cf = 20,83%)
2015 - 0,72 months of energy storage required (Cf = 25,60%)
2016 - 0,79 months of energy storage required (Cf = 27,49%)

Topaz Solar - 550MW Fixed
2014 - 1,64 months of energy storage
required (Cf = 21,86%)
2015 - 0,77 months of energy storage required (Cf = 27,00%)
2016 - 1,10 months of energy storage required (Cf = 26,27%)

Energy density of Lithium Ion VS Hydrogen

Lithium Ion VS Hydrogen. How do these two energy storage mediums compare? Representing Team Electric we have the Tesla Model S and representing Team Hydrogen we have the Toyota Mirai. 

A Tesla Model S with a 85kWh battery pack contains 7104 cells. Each cell is 65mm tall, have a diameter of 18mm, weighs 45g and contain 0,01258 kWh of energy. Specific energy density, is 0,279kWh/kg and volumetric energy density is 0,760kWh/l. Total weight of the battery cells adds up to 320kg.

However, these numbers are best case scenario. The battery cells need to be contained in a structure, be fitted with a cooling system etc. and all this adds another 220 kg which gives you a total weight of 540kg. Also, some of the battery capacity is reserved in order to increase cycle life and the geometric shape off the battery cells greatly reduce the volumetric energy density. Final specific energy density is 0,155kWh/kg, and volumetric energy density is no higher than 0,597kWh/l.

So how does hydrogen compare to lithium ion?

- Hydrogen specific energy density = 39,44 kWh/kg (141X Tesla 18650 cell)
- Hydrogen volumetric energy density = 2,79 kWh/l (3,67X Tesla 18650 cell)

Seems like a superior victory to team hydrogen, right? Well it`s more complicated than this.

1. You can`t really store hydrogen as liquid so you have to store it as compressed gas instead. When stored at 700 bar the volumetric energy density is lowered to 1.60 kWh/l.
(Internal tank volume is 122,4 liters and the hydrogen capacity is 5kg)

2. With a pressure of 700 bar you need a very strong tank wich adds at a lot of weight and quite a lot volume. The Toyota Mirai hydrogen tank(s) contains 5kg of hydrogen but the tank(s) itself weighs 82,5kg and have an estimated external volume of 150 liter = 1,3kWh/l.

3. The fuel cell weighs 56kg and occupy 37 liters of space. A device called fuel cell boost converter add another 13 liters of space.

4. The 1,6kWh nickel-metal hydrate battery is estimated to weigh 14kg and have a volume of 6 liters.

5. The fuel cell efficiency is around 50%. Available energy: 5kg ⋅ 39,44kWh/kg ⋅ 0,5 = 98,6kWh.
(Fifty percent effiecency is quite optimistic since I have used hydrogens "higher heating value". Lower heating value of hydrogen is 33,33kWh/kg.

6. The fuel cell create a lot of heat which require a big cooling system. This adds weight/volume and increase drag. No data.


Final specific energy density is maximum 0,62kWh/kg, and volumetric energy density is no higher than 0,48kWh/l.

Conclusion: Team Hydrogen wins the specific energy trophy (+400%) and Team Electric wins the volumetric trophy (+25%).

To be noted: The hydrogen numbers are quite optimistic since a lot of data is missing!