Final answer:
The main energy source during the first phase of industrialization was coal, used to power steam engines, which significantly boosted the efficiency and location flexibility of factories.
Step-by-step explanation:
The main energy source during the first phase of industrialization was coal.
Initially, factories utilized water power through the use of water wheels and turbines to operate spinning and weaving machines. However, with the advancement of technology, the steam engine, developed by James Watt, became predominant.
Coal-powered steam engines revolutionized the industry by enabling factories to be located closer to urban centers and not just by waterways. This shift increased the efficiency of production and transportation, making coal an essential element for the growth of the Industrial Revolution.