Power and Energy

People often get confused about power and energy. To understand what you need from an independent power plant, or what you can get from your independent power plant, you need to be clear on the relationship between these two concepts. When we use energy, we use it to do work, whether that work is heating or cooling our home, cooking on the stove, being lifted up a building in a lift, or moving around in our car.

Energy is all about being able to do work when we need to. Energy can be stored so that it can be used  to do work as we require it. Energy can be stored in many ways: as a wound-up spring, as compressed air, as pressurized steam, or as a suspended weight in an old clock. One of the common ways that we store energy is as chemical energy. The fuel that we use in our cars is chemical energy: it contains large molecules that are broken down into small molecules to release energy when they are burned in the engine.

The large molecules (hydrocarbons of petrol or diesel fuel) are the stored energy. The fuel in a car’s fuel tank is its energy – it represents the amount of work that the car can do; in this example of a car, that’s  the distance that it can be driven.  A certain amount of fuel means that the car can travel a certain distance. If, as we drive, we push the accelerator down harder the engine will produce more power and the car will go faster.

To produce more power the engine will use fuel (energy) faster.  However, we will also get to where we are going sooner; so even though the engine is producing more power, we will use the same amount of fuel (energy) to do the same amount of work. (Although, travelling at higher speed is less efficient, so we will use a little more fuel in practice.) Simply: energy is the capacity to do work power is the rate at which work is done (the rate at which energy is used.) 

For an independent power plant the energy is stored in the storage battery bank as chemical energy (lead oxide and Sulfuric acid.) The charge in the storage battery bank represents the work that can be done for you by the power plant if no charging occurs from the generator set or solar panels. Different items of equipment that you run from your independent power plant use the energy from the storage battery bank at different rates, that is, they draw different amounts of power.