2019-12-31 (Réveillon!)

Today, I learned about:

Once again, it is that day of the year when we reflect over how the year behind us was and make our predictions and wishes for the year to come.

One important piece of news during 2019 was that researchers at my alma mater Chalmers University of Technology, Gothenburg, Sweden, led by professor Kasper Moth-Poulsen reported that they have developed a molecule, that is able to capture the sun’s rays, store it as chemical energy for up to 18 years, and retrieve the energy and convert it into heat when needed.

The following graphic shows how it all works:

It all starts in the upper middle section of the sketch. The solar reflector (SOLFÅNGARE) placed on the roof of a building captures the sun’s rays. The parabolic section concentrates solar energy and transmits it to the liquid in the tube in the center of the solar reflector. From there, the cold liquid, now containing stored chemical energy, is sent to an energy storage (ENERGILAGER). It can be stored there for up to 18 years! When we need to heat up our house, we simply let some of the liquid out from storage, run it through the catalyst (KATALYSATOR), thus obtaining a hot liquid without any stored chemical energy. Experiments have shown that the liquid with released heat can have a temperature that is 63 °C higher after the catalyst in relation to before! The hot liquid then goes into the normal heating system of the house, e.g. the radiators (ELEMENT I HUS) in the various rooms, heats up the ambient, and then the now cold liquid goes back up to the roof to capture more sun rays. Graphic made by Yen Strandqvist.
The leftmost photo shows the parabolic solar reflector with the liquid tube in the center. To the right is the inventor of the material, professor Kasper Moth-Poulsen, securing a small sample of the miraculous liquid. All material has been extracted from Chalmers Magasin no. 1 2019, text by Karin Aase and photos taken by Oscar Mattsson and Johan Bodell.

References # 1 through 4 below contain more material if you are interested in further details.

Can you use an hourglass?

According to Wikipedia: “An hourglass (or sandglass, sand timer, sand clock or egg timer) is a device used to measure the passage of time. It comprises two glass bulbs connected vertically by a narrow neck that allows a regulated flow of a substance (historically sand) from the upper bulb to the lower one. Typically the upper and lower bulbs are symmetric so that the hourglass will measure the same duration regardless of orientation. The specific duration of time a given hourglass measures is determined by factors including the quantity and coarseness of the particulate matter, the bulb size, and the neck width.

So you think are smart? Then show it now! We have two hourglasses like the ones shown above. The bigger ones completes one cycle in 11 minutes, the small one in 7 minutes.

Question: Using a combination of these two hourglasses, you need to measure a time lapse of exactly 15 minutes. How would you do it? (Solution to follow in the first blog post of 2020.)

I wish all my faithful blog readers a HAPPY NEW YEAR!

That’s what I learned in school !


1: Extract from Chalmers Magasin nr 1 2019 (article in Swedish)

2: An energy breakthrough could store solar power for decades

3: Storing the energy from the sun for decades

4: Liquid sunlight creates heat on demand

*: What did you learn in school today ?

2017-07-05 (Wednesday)

Today, I learned that:

Finally, we are about to have an international system of measures that will be based entirely on Mother Nature. I am of course talking about the International System of Units (SI system), which has its origin in 1875, when the two references for length and mass were decided. It has ever since grown to comprise seven base units, of which six are derived by using natural phenomena. See references #1, #2, and #3 below. The following illustration is contained in the last of those references, and it also develops the matter further in an elegant way:


However, the seventh base unit, the kilogram, is still an object manufactured in 90 % platinum and 10 % iridium. It is kept in a safe in Paris and has copies spread out over the world. There are several negative remarks that can be made to such a procedure, the difficulty of accessing the object, the wear and tear that the atmosphere exercises on the object, etc. So, if everything goes as expected, in November 2018, there will be a congress deciding to abandon the physical mass reference and substitute it with something based on non-changing conditions.

The new reference will be based on Planck’s constant. A highly precise balance operates on the principle of electromagnetic force compensation. In it, a weight on one side is balanced by the electrical force on the other. This electrical force is linked to Planck’s constant and can therefore be directly referred to as the new kilogram definition. See reference #4 below.

And while they are still at it, how about also changing the base unit from something which includes a prefix (as you know kilo means 1000) to a neutral one? My suggestions is that the seventh base unit should be named planck, abbreviated P, to which the normal prefixes would be used, when necessary. For instance, gram (g) would be mP (milliplanck) and the ‘metric’ ton, currently 1000 kg, would be 1 kP (kiloplanck). In the old CGM system of measures, there is a P which standards for Poise, the unit for dynamic viscosity, but in the SI system it has already been substituted by Pa.s (pascal-second), where 1 Pa.s = 10 P.

The photo below was taken in the strait of Kattegat on the Danish side on 2017-05-25, when I flew from continental Europe to Gothenburg. It shows the Danish wind farm close to the island of Anholt, one of the ten biggest in the world. Due to the altitude, it may be difficult to see, but each one of those small white spots is a wind turbine. See also reference #5 below.


A large Danish wind farm, located in the sea between Denmark and Sweden, close to the island of Anholt. Photo taken on 2017-05-25.

Since this time of the year is appropriate for many people in Europe to take vacation, what could be better than “sol, vind och vatten” (sun, wind, and water), which the fantastic Swedish song writer Ted Gärdestad described so well in reference #6 below?

And did you know that renewable energy is the cheapest one to acquire? According to professor Tomas Kåberger of Chalmers, it occurred already in 2016! An article describing that and many other interesting correlated facts can be found in reference #7.

… That’s what I learned in school !

1: International System of Units

2: Para manter o peso

3: SI base units

4: Researchers developing a new balance for the new kilogram

5: Wind farm

6: Sol, vind och vatten

7: Njutbar nedgång för priset på förnybar energi

*: What did you learn in school today ?