Sir Benjamin Thompson, also known as Count von Rumford, was one of the founders of the Royal Institution. Throughout his scientific life, Thompson was fascinated with investigations into heat and energy. During his experimental work he made several discoveries around heat retention and energy efficiency that help us, amongst other things, cook more sustainably today. Thompson was able to prove that heat is a form of motion, improved the design of chimneys and fireplaces so that the heat and not the smoke came into a room, invented a double boiler, drip coffee pot and the kitchen range! Furthermore, through an experiment with a lamb shoulder, he accidentally discovered the sous vide method of cooking meat for a long period of time over low heat. This method has evolved, and now food is vacuum-sealed and cooked in water at a low temperature! Even though these findings changed the way we view energy efficiency, our current cooking methods could be a lot more sustainable. A study in the UK found that up to 61% of emissions from producing certain foods can come from home cooking. There are many alternative cooking methods that could reduce this percentage.
First of all, microwaves, slow cookers, pressure cookers and air fryers are all more energy efficient than conventional ovens. Microwaves are particularly energy efficient, although there are certain foods that they are not suitable for heating. Microwaves work through releasing electromagnetic waves, called microwaves, into the food. These waves then cook the food using radiation heating, which means that energy is transferred to the molecules within the food. For thick foods where energy is unable to travel into the insides of the food, the waves heat the outside of the food, which then transfers energy to the inside. Have you ever been told not to put plastic or metal into a microwave? In fact, this is because some plastics can absorb microwaves and melt into the food, while metals reflect and interfere with the movement of microwaves. When cooking foods where it is possible to substitute a conventional oven for the microwave, doing so will help reduce carbon emissions!
Two other cooking methods that are energy efficient include using a slow cooker or pressure cooker. In a pressure cooker, the water that turns into steam is unable to escape from the cooker, which causes the pressure to increase to twice the pressure of the normal atmosphere. This increase in pressure allows the temperature of the liquid to rise higher than the boiling point of water. Since heat cannot escape, this high cooking temperature is maintained, which allows the food to be cooked much faster. Meanwhile, a slow cooker involves cooking food at low temperatures over a longer period of time. This saves energy and also prevents the nutrients in the food from being destroyed by intense heat!
Using materials that conduct and retain heat well can also help conserve energy when cooking. Thermal conductivity measures how well a material conducts heat; this value can be found through measuring the time it takes to transmit energy through a material. A high thermal conductivity value indicates that the material heats fast and would be an efficient material to use in cooking. In fact, Thompson’s work around heat relates to this since he overturned the claim that heat is a liquid form and laid down the concept of heat being a form of motion! Other ways of saving energy include cooking many items at once to maximise the use you are getting out of the energy used, or cooking with a lid on so that the heat cannot escape. Overall, Thompson’s exploration around heat and energy has been extended to find energy efficient methods of cooking, which we must employ to combat climate change.