Low carbon footprint hummus (super fast and economical to make)

Ingredients: Chick peas, garlic, tahini,
lemon juice, salt

Hummus is one of the tastiest things to eat for lunch on bread. It's also super easy to make yourself, even from a store cupboard if you're trying not to go outdoors (the COVID-19 pandemic is a very big problem at the moment in the Netherlands).

So if you're stuck for something tasty to put on bread for lunch, consider making hummus. It takes far less time than going to the shops, it's cheaper than commercial hummus and the result is tastier.

The ingredients required as all easily stored except for the garlic. The only fresh ingredient needed is garlic, though you can use garlic from jars if required.

In this example I used a 400 g tin of chick peas, one table-spoon of olive oil, a couple of tablespoons of tahini and small squirt of lemon juice, four cloves of garlic and a tea-spoon of salt.

Drain the chick peas, but keep the liquid. You'll find you need to add some liquid while liquidizing and this is the best thing to use. Keep any which is left over for use as liquid in other recipes (it'll go off if left too long - I put seal on the tin and use within a day or so).

The exact proportions of ingredients are not important. You can vary them to suit your taste buds and also to suit what you have in stock. Even the main ingredient, chick peas, isn't really necessary. OK, so real hummus may be a chick pea dish, but exactly the same procedure can be followed with any kind of tinned or pre-cooked bean and it you get a similar tasty result. So if you need something to spread on your bread and don't have any chick peas, try some other bean. For instance, black-eyed beans make a great spread as well.

Super simple - just put everything in a liquidizer. No cooking is required. Note that everything is shown "dry" here. It's always necessary to add some of the liquid from the chick pea tin to make it liquidize properly. You can also vary that according to taste - some like their hummus to be more liquid than others. If you don't have a liquidizer you can simply mash all the ingredients together. 

After 30 seconds or so it'll look like this. Stop when you like the consistency. It's immediately ready to serve.

One 400 g tin of chickpeas and the other ingredients together make about enough hummus to fill two average commercial retail hummus containers. We buy these only occasionally and when we do that we keep the containers which can be re-used many times. The red specks are due to an optional extra ingredient - I included a red chilli this time around. Other spices or herbs can be added in the liquidizer at the start.

Lunch. This recipe always makes delicious hummus.

Carbon footprint

As before when I made a pizza, I wanted to calculate the carbon footprint of this meal. It won't be very high for the calories because vegan food never is. And in this case it'll last for a few days of lunches so the cost per day will be low anyway. Unfortunately, I couldn't find accurate figures for the chick peas or tahini, so I warn you in advance that the following figures are to a large extent guess work. Perhaps you can help with this.

The first part is easy. The liquidizer consumes 1000 W but it's required for only a very short time. Less than 30 seconds in total. Therefore the total amount of energy consumed is very small. This works out as about about 8.3 Wh, or 0.0083 kWh. Due to the full sun today the only effect that it really had was to make our electricity meter run backward less quickly but I've calculated here as if we were using the average carbon footprint for electricity across Europe. Even so, the liquidizer doesn't do much harm:

Ingredient	Quantity (g)	CO2 equivalent (kg/kg)	Total CO2 (g)	kcal
Electricity	0.0083 kW	500 g/W	4.2
Chick peas	400	0.7	280	468
Tahini	30	2.3	69	170
Olive oil	10	1.5	15	80
Lemon juice	10	0.5	5
Salt	1	0	0
Total carbon footprint / calories			373.2 g	718 kcal

As explained before, I cannot claim this time that the figures above are in any way accurate. The carbon intensity of tinned chickpeas and of tahini are both based on figures that I found (here) for similar ingredients. I picked "ready to eat meals" for the chick peas and "Nuts and almonds" for tahini (which is ground up sesame seed). As those two items dominate the total this makes the entire result questionable. However I have picked replacement values which are on the high side so I would be surprised if the carbon footprint of hummus made this way is greater than what is shown above.

I hope that readers can contribute better sources for those ingredients.

How much did it cost to make ?

These cheap chickpeas cost about 60 cents a tin, the small amount of Tahini is worth about 20 cents. The other ingredients perhaps 10 cents at most between them. That makes for a total cost of probably less than 90 cents for an equivalent amount of hummus as is found in two commercially made pre-prepared packs which cost about €2 each.

What about dried chickpeas ?

Dried chickpeas have a lower carbon footprint when sitting on your shelf than does an equivalent quantity of tinned chickpeas. However a lot of energy is required to boil them at home. I therefore would expect a higher carbon footprint for chickpeas that I boil myself than is the case for those bought in a tin where economies of scale will make the process more efficient, almost certainly more energy than is consumed in making the small amount of steel in a can. This seems to be confirmed by various sources.

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.

Instructions
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
Salt	0	0	0
Tinned tomatoes	100	0.3 (vegetable juice)	30	19
Peanuts	10	2.3 (nuts and almonds)	23	61
Onion	30	0.2	6	12
Garlic	10	0.2	2	3
Cabbage	30	0.3	9	7
Capers	5	0.1	0.5
Herbs, salt, pepper	5	0	0
Total carbon footprint / calories			256.5 g	662

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.

Conclusion
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.