I imagine that you have, like me, wondered what is the most efficient way of cooking some pasta and what is the cheapest way. Well after years of waiting your prayers have been answered and I have determined the cheapest, the most energy efficient and the quickest way of cooking 0.5 kg of good quality dry pasta.
{I am probably alone in the world in this, but hey, isn't the internet great, I can ramble on about things that nobody cares about and pretend it is all very important, so back in the reality distortion field}
I know you are excited about this, but calm down and refrain from just reading the conclusion, hundreds of man hours have gone into this research, don't you think that it deserves your full attention?
I have systematically measured the amount of time 2.5 Kg of water take to boil, using different methods. Note that it is assumed throughout that the density of water is equal to 1kg per liter (an error of 0.02%). The main gas meter has been used to measure the amount of gas used for the different conditions and where appropriate a Brennestuhl BS-PM230 has been used to measure the electricity used. Gas cost is 4.44p/kWh and Electricity cost is 11.57p/kWh.
It was not possible to measure the water temperature before starting each measurement, but it can be estimated that a variance of no more than 2 K occurred ( Did you notice that? I'm using Kelvin instead of degrees celcius to give the impression that this is a serious piece of research)
Without Lid
The first experimental condition I wanted to test was to cook the pasta on the gas hob without a lid covering the pan.
It took 1073 s for the water to be boiling, an error of ± 60 s has been estimated. The error is chiefly due to the observer deciding when the water is boiling "enough" for the pasta to be dropped in.
The total gas used was 0.08 m³.This is equivalent to 0.89 kWh and I payed 3.93 pence for the privilege.
With Lid
I then repeated the same experiment, but this time the pan had its lid, which completely covered the pan.
It took 993 s for the water to be boiling, an error of ± 60 s has been estimated. The error is chiefly due to the observer deciding when the water is boiling "enough" for the pasta to be dropped in.
The total gas used was 0.06 m³. This is equivalent to 0.67 kWh and the total cost was 2.95 pence.
I should comment that after the water boils, it only takes about 12 minutes for the pasta to be ready. When cooking with a lid, the gas used is reduced as a lot less heat is necessary to keep the water boiling. The difference here is small, but I hypothesize that it will be much more significant for beans or chickpeas that take about 1 hour to be ready.
Kettle Assisted Without Lid
In this case, I filled up the kettle with 1.8 Kg of water and the remaining 0.7 kg were placed in the pan, which was left uncovered. The kettle and the pan were simultaneously boiled.
The kettle took 353s to trigger the automatic stop and the water in the pan took a further 120s to boil, therefore the total time for the water to be ready for the pasta to be dropped in was 473 ± 60 s. The total amount of gas used was 0.048 m³, this is 0.54 kWh. The total amount of electricity was 0.19 ± 0.005 kWh. Therefore the total energy used was 0.75 kWh, for a cost of 4.56 pence (2.2 pence in electricity and 2.36 in gas)
Kettle Assisted With Lid
In this case, I filled up the kettle with 1.8 Kg of water and the remaining 0.7 kg were placed in the pan, the pan was covered with its lid. The kettle and the pan were simultaneously boiled.
The kettle took 343s to trigger the automatic stop and the water in the pan was ready by then, therefore the total time for the water to be ready for the pasta to be dropped in was 343 ± 60 s. The total amount of gas used was 0.032 m³, this is 0.36 kWh. The total amount of electricity was 0.19 ± 0.005 kWh. Therefore the total energy used was 0.45 kWh, for a cost of 3.77 pence (2.2 pence in electricity and 1.57 in gas)
With all this in mind, we can clearly declare that kettle assisted cooking with the lid on is the quickest and less energy consuming way of cooking pasta.
The cheapest way is to cook with the lid on, entirely on the cooker. This method will take an extra 10 minutes and will save you around 0.82 pence a pop. While it might be a pitiful amount, you only need to plan ahead a little bit or wait an extra 10 minutes for your pasta to be ready. After all, you know what Tesco says: Every little helps.
Incidentally, the most environmentally friendly way of cooking your pasta is a toss up between kettle assisted and gas only. Assuming a rather generous 40% efficiency for electricity generation, those 0.19 kWh are actually 0.475 kWh of coal, gas or nuclear and assuming 10% transport cost for gas, it is 0.4 kWh, so in total 0.875 kWh are needed to generate the energy needed to cook the pasta for the kettle assisted cooking with lid on. A similar calculation shows that gas only with the lid on is 0.74 kWh. Gas will also heat up your kitchen which is a nice by-product in winter but might not be so good in the summer.
I am happy that with the above I have answered one of the last remaining unanswered questions troubling mankind.
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