Scientifically, energy implies the inherent property in a substance that can be used for constructive purposes by mankind. For instance, when we talk about thermal energy of the petroleum products, it means the heat energy it unleashes during combustion. Automobiles, aircrafts, locomotives are some of the examples where the thermal energy produced by fuel is brought to mechanical use. Energy can be harnessed from many sources such as fossil fuel, sun, wind, flowing water, fissile material, etc.
Although nature has endowed us with vast amount of fossil fuel, we will have exhausted almost all sources if the present rate of consumption is to continue. To prolong the availability of fuels, we should adopt measures to minimise energy consumption. For instance, pressure cookers cut cooking time as well as gas consumption considerably. Most people hold an erroneous view that the bigger the flame, the shorter is the cooking time. No matter how much heat is applied, once the liquid starts boiling, excess heat is simply wasted. The law of thermodynamics states that once a liquid attains boiling temperature, no matter how much heat is applied, the temperature cannot be increased.
Secondly, food should not be cooked for any longer than is necessary. By doing so, not only is the nutritional value of food retained but a good amount of fuel is saved as well. Even if the gas is turned off earlier, say by five minutes, the super-heated steam enclosed inside the container continues to cook food for some time.
Most of us have a habit of transferring cooking items straight from the refrigerator to the cooking stove. This is another area where we waste fuel. The temperature inside the freezer is around 5 degree Celsius while the room temperature is around 25 degree during summer time. If the food item is retrieved from the freezer well ahead of the cooking time, its temperature will automatically rise by absorbing heat from the surrounding atmosphere without the application of more artificial heat.
Gas stove should be turned on only when fire-producing objects like matchbox, lighter or electronic sparking device are handy; and only appropriately sized utensils should be used. Unnecessarily big utensils consume more fuel without any attendant benefit. When using utensils other than a pressure cooker, they should be covered with lid to prevent entry of foreign particles. Without contamination, the steam generated inside the container helps cook food faster.
According to crude estimates, one household saves an average of 15gms of gas a day by following these simple recommendations. With 100 million households using cooking gas across the globe, daily savings in consumption of this precious resource or its equivalent amount of other fuel would come to a staggering 1,500 metric tons. Apart from conserving natural resources, this also leads to lower emission of carbon dioxide, a gas responsible for greenhouse effect and global warming.