Load profile is a general term which can refer to some different types of data. Most of the times, load profiles are used to show electrical (or sometimes heat+electrical) energy demand or consumption on a period of time, divided in hours or days or months and so on. The common point about all these forms is that integral of each of these diagrams results in total consumption in that period of time (kWh). So if you have demand (kW) on your vertical axis, then you should have hours on your horizontal axis and if you have consumption (kWh) then you should have number of days on your horizontal axis.
There are two main methods to draw a load profile, Autonomy method and 24 hours method. These two methods use exactly the same data which is “how much power do we need every hour” but the difference is in the way we organize and demonstrate these data. In autonomy method we order amount of demand in descending order rather than chronologically but in 24 hours method this value is ordered chronologically. The main use of autonomy method is to determine size of back up system because it can tell us what is the maximum power and period of time that we need it so we can select an appropriate battery. In 24 hours method we see exactly when we demand how much power so we can try some solutions to cut the peaks in our load profile and have a more even profile.
Now we know what load profile is and what kind of data it is showing us, let’s get in to our main topic, what is the secret concealed in it that we (or our politicians!) should be aware of?
Load profile shape depends on many factors like season or culture of the area of study or price of energy. But a side of all these factors the main difference between load profiles in various countries (forget about the magnitude, we want to discuss the shape of load profile) is because of industry in those communities. For example, Iran is called a developing country (which is polite form of not-Developed!) so it doesn’t have many industrial towns or units, therefore its demand is mostly generated because of domestic segment. Domestic demand makes two peaks in peak hours (two local peaks) which are about 9 AM and 8 PM and there is lower demand from 9 AM to 8 PM with lots of fluctuates but there is almost no demand from 12 PM to 8 AM, Why? Because people are asleep and since there isn’t many industrial units or 3 shift units, they don’t have much demand. So basically, most of demand in developing countries is caused by domestic segment and its peaks are made by consumptions like lighting or electrical kitchen appliances! But if you look at developed country’s load profile, like Japan or USA, we will notice that they have high demand all day! Which means their industry is like an always-hungry baby and it’s consuming lots of power even at nights when domestic users aren’t using any power. This huge consumption at nights, causes even load profile with little fluctuates (in comparison to base load).
Well, which one is better? Rectangle-like load profile of developed countries with their huge base loads or developing countries load profiles with two local peaks and little base load?
As a leader of a country, you should provide your people with enough power which comes from power plants, so you should have as much power plants as they can cover your load profile peaks. If your demand peaks are created by domestic segment, then you have established thousands of Megawatts only to maintain consumption of Lamps or Televisions or coffee makers at dwellings! Which brings you no GDP (Gross Domestic Product) and this is where developed and developing countries are distinguished. In developed countries most of load profile is shaped because of their industry, the part that brings high GDP for them. Thus they have no worries for their high consumption and establishing new power plants because their power is consumed in industry not domestic part. Also, even and soft load profile helps network regulators to control and observe the whole network more easily.
Just to have a rough estimation of consumed energy in industry to consumed energy in domestic segment in Iran and USA we can calculate these ratios by looking at Energy Flow diagrams for both countries. I didn’t find Iran’s energy flow diagram in English, so try to read Persian numbers 😀
As you see we have divided industrial consumption (Red rectangle) to domestic consumption (Blue rectangle) and the ratios are as below:
*The units are different in two diagrams, we just want to check the ratios.
USA industry to domestic ratio = 21.78/11.26 = 1.93
Iran industry to domestic ratio = 301.9/440.7 = 0.685
As you see USA ratio is almost 3 times more than Iran’s ratio which shows huge difference in domestic and industrial consumption in these countries.
So we shouldn’t be happy if our country is consuming lots of energy in domestic segment although our government may provide it for us. Instead, if we have high consumption in industry it’s good sign for us which shows we are spending our power in appropriate part that brings us high GDP.