Wednesday 30 October 2019

The forgotten energy saving potential of the microwave oven (also quick low impact vegan pizza recipe)

The recipe book which came with my
first microwave over in the 1980s
Click these links for the recipe without the story, to find out how much CO2 was emitted, or for how far you can cycle using only the energy in the pizza.

Back in the early 80s I bought a microwave oven for my mother with some of my earnings from my first job. Microwave ovens were not really a new invention but they were not entirely commonplace yet in the UK. I don't think my Mum really wanted a microwave at the time, but she became quite convinced by it and made quite good use of it because it allowed some recipes to be cooked just as well before, but in less time. A year or so afterwards I packed in the dead end job and became a student but my accommodation consisted of one room in a building with no shared kitchen. For several months I ate nothing but salad for my evening meal, which was healthy enough but ultimately not so varied, so I bought a second microwave oven and began to learn to cook with it.

Microwave ready meals were not really a thing in the early 1980s so people didn't buy microwave ovens merely to warm up frozen pizzas. Because many owners had no previous experience with microwave ovens they were supplied with information about how the oven worked, what it was useful for, and complete recipe books. My first microwave oven was a Samsung and it came with this book.

They were both full of tempting looking meals,
completely cooked by microwave
Inside the Samsung book there were a wide range of recipes some of which became favourites during my student days. However this book was of course aimed at every potential buyer so it included a lot of non-vegetarian recipes which were of no use to me so I bought a second book which while not completely vegetarian did include a lot more recipes for things that I wanted to eat.

I ate fairly healthy food when I was a student, and very nearly every evening for a period of years I prepared my meal in the microwave oven, everything cooked from fresh ingredients. The budget was small but the food was good.

Microwave ovens are not the best way of cooking every type of food. Some of my experiments as a student were not total successes. For example, at that time I didn't understand about how bread was made and I once ended up making my lunch sandwiches out of incredibly dense lumps of dough for half a week because I couldn't afford to throw anything away. But microwaves have advantages for some kinds of cooking.

The forgotten potential
My old microwave cookbooks include short descriptions of why microwave cooking is advantageous. For instance, the microwave oven consumes far less energy than a conventional oven to achieve the same result, it saves time and it's less dangerous to use because it doesn't get hot in itself.

Much of the potential seems to have been forgotten with microwave ovens now being seen by many people as useful only to warm up low quality frozen food.

We've done this with our produce. Quick, easy and effective.
There is more awareness now than there was 35 years ago that we really should be trying to consume less energy, but while we now have an image of ourselves as being "green", we actually consume twice as much electricity now as we did back then. The average person was actually more frugal before anyone had LED lighting in their home or solar panels on their roofs.

These books are full of recipes for proper food.
Now, more than ever, we need to address our excessive energy consumption and enormous CO2 emissions. We can start in the kitchen. Switching to a vegan diet is of course enormously beneficial because a plant-based diet produces far lower emissions than does a meat and dairy based diet. But we can go beyond just the savings due to the ingredients we use by changing how we cook.

An online discussion a few days ago revealed how remarkably energy and carbon intensive a pizza can be if it is a frozen pizza, warmed up and delivered to your home. There's no obvious reason why a pizza should be so damaging. It is, after all, basically just tomatoes on toast. However this prompted me to think about one of my favourite dishes when I was a student: microwave quick pizza. This took no time to make and included no exotic ingredients so surely had a low footprint.

Quick low impact inexpensive vegan pizza

I clearly referred to this page quite often
when I was a student.
When I was a student, one of my favourite recipes was a basic microwave pizza. This took less than 15 minutes to cook from scratch, it was very simple, it was tasty and it was nutritious.

The original quick pizza recipe which I used as a student of course used cheese as a topping, but I've been vegan for decades now and so I always substitute something else. There are many commercial cheese substitutes. I've tried most of them in the past, some are better than others and you may well find one that you really like. However we cook from basic ingredients every day so we don't usually have things like "vegan cheese" in our refrigerator. For the pizza which I've made for my lunch today I've used nuts as a substitute for cheese. That may sound a bit, well, nuts, but it's not actually a bad substitute. Nuts contrast with the tomato, they provide protein and oil as does cheese and in any case many commercial vegan "cheeses" are made at least in part of nuts.
Ingredients for the base (makes one pizza)
120 g self rising flour
20 ml olive oil
35-45 ml water
pinch of salt

Ingredients for the topping
100 g tinned tomatoes, drained.
10 g peanuts, crushed.
1/2 small onion.
2 cloves garlic.
Basil, oregano, salt and pepper, nutritional yeast to taste.

Mix all the base ingredients together into a dough. Add the water slowly as you want a nice dough and not something too sticky.

Slightly oil a plate and spread the pizza dough on it. It's not a bad idea to make sure that the sides are slightly high to contain the topping, but the topping shouldn't really be wet so this isn't actually very important.

Microwave on full power for about 3 minutes. The pizza base will become puffy and rise slightly.

While the base is in the microwave you have time to drain the tomatoes (if they're too wet then the entire pizza will be too wet), chop them, crush the peanuts in a mortar and pestle and also finely chop the onion and garlic.

When the pizza base is ready, spread the onion and garlic on top and microwave for two more minutes. This softens the onion a bit, which doesn't happen so readily if you put it in with the tomato already on top.

Now add the tomato, herbs and crushed nuts and microwave for another 3-4 minutes.

Add salt, pepper, nutritional yeast to taste.

Perhaps not the best pizza in the world. Perhaps some people wouldn't even consider it to be a "true" pizza. I don't much care. It's tasty, nutritious, quick to prepare from scratch and it's all I've got for lunch today.
I like cabbage, perhaps more than most people, so I added some of that to the topping as well at the same time as the onions and garlic. I also added capers before the last microwave step and I topped it off at the very end with a few small tomatoes from our garden (it's nearly November but we still have the last of the fresh tomatoes) and a few basil leaves also from the garden. You can add anything you like.

Obviously if you're alergic to peanuts you should substitute something else. Nothing is very critical. It will probably also work with gluten free flour.

Note: This isn't a real bread recipe. It's more like a recipe for a scone (you can make good scones in the microwave). The rising action in this case is the result of a chemical reaction with the sodium bicarbonate in the self rising flour. This chemical is all that distinguishes self rising flour from normal flour and you can just add a tiny quantity yourself (its sold as baking powder) to normal flour if you want. Baking with yeast is different. If I had know about that difference when I was a student I wouldn't have had to eat solid bread for a week (see story above).
0.08 kWh consumed in
the 19 minutes it took to
make the pizza, write
down what I was doing
and take all the photos.

A low carbon meal

Having cooked and eaten the pizza we can now calculate the CO2 emissions which resulted from it. The electricity is easy: There are articles online which show the carbon intensity of electricity for different countries. Exact figures vary but for the Netherlands, and across Europe, around 500 g/kWh seems to about average. My plug-in usage meter measured 0.08 kWh used in total by the microwave. Generating that amount of electricity would normally result in about 40 g of CO2 being released. Because I cooked this pizza at lunch-time the microwave oven was actually entirely powered by our own solar panels. The electricity meter span backwards the whole time. But I will stick with the 40 g for this calculation as it's more representative.

Impacts for the ingredients are taken from this link (it refers to Finland, but I can't see most of them would vary much elsewhere).

Ingredient Quantity (g) CO2 equivalent (kg/kg) Total CO2 (g) kcal
Electricity 0.08 kWh 500 g/Wh 40
Flour 120 0.8 96 400
Olive oil 20 1.5 30 160
Water 40 0.5 (for mineral water. I used tap water) 20
Tinned tomatoes1000.3 (vegetable juice)3019
Peanuts102.3 (nuts and almonds)2361
Herbs, salt, pepper500
Total carbon footprint / calories256.5 g662

So I've calculated that my lunch had a total impact calculated of around 260 g CO2. I've been a bit unkind to myself because our electricity has a lower impact, at least in the daytime, and my water definitely has a lower impact as it came from the tap - I never buy mineral water so in this case around 200 g was probably more accurate. Either way, the total is small enough to fit into most carbon budgets.

The total weight of the finished pizza was about 370 g (very little liquid had a chance to evaporate, and the rest of the ingredients stayed in the plate). So the impact of a pizza made in this was is 0.7 kg CO2/kg food. This makes sense because it's somewhere in the middle of the impact of the ingredients themselves. It's a very long way removed from the 19 kg/kg figure given at the link for "pizza", but it's clear that what they're referring to is a ready made or delivered meal of some kind.

Another study suggested that a frozen pizza in Norway could have an impact on the climate equivalent to as much as 290 kg CO2. My recipe has less than 1% of that impact.

Following the recipe above you too can make a pizza which is quick to prepare, tasty, nutritious and has about 1/30th of the environmental impact of a delivered pizza. If it had been cooked in a conventional oven then the energy consumption would have been far higher. The energy saving potential of microwave ovens is largely not appreciated, but it should be. We are killing our planet with over-consumption of many things, including energy.

Addendum: What can we do with 662 calories?
662 calories is more than a quarter of the daily requirement for an average man and very close to a third of the recommended daily for an average woman. We need to eat that amount every day just to be healthy. We also need to exercise for about half an hour every day. So let's work out what can be achieved by using those calories.

We should always bear in mind that we need 30 minutes of exercise every day just to maintain a healthy body. In 30 minute we can cover 15 km on a bicycle, so by cycling we effectively get 15 km of travel for free every day with no impact on the environment over that of the food we have to eat anyway.

Velomobiles are the most efficient vehicles on the planet. But can you get a
subsidy to buy one of these ? Of course not. However the Dutch government
will give you €6000 to buy an electric car which produces far more pollution.
However if we ignore that and simply plug the calories that we have into a calculator and work out the potential then we find that with a standard town bike we can ride an impressive 32 km at just over 20 km/h using nothing more than the energy from the pizza. If we use a more efficient type of bicycle then we can cover 46 kms at 30 km/h using just that pizza as fuel. That works out as about 5.65 grams of CO2 emissions per km for the efficient bicycle and about 8 g CO2 per km for a standard bicycle. By comparison, in the Netherlands, an electric car produces about 60 g CO2 per km and a diesel car anywhere about 120 g per km.

A cyclist can easily travel with a tenth of the emissions of the driver of even one of the most efficient cars, but even that comparison is unfair because actually we get our first 15 km for free.