Compare two transmission lines: one at twice the voltage of the second. Which of the two lines is most advantageous to a utility company? How much is the advantage?

Advantage has multi facets.

With twice the voltage, the joule heating will be 1/4 less if the same amount of power is transmitted (Power=V^2/load), or, four times more power can be transmitted with the same loss. Or, the area of the transmission lines can be 1/4 the original size (smaller, lighter wires) for the same power transmitted and losses.

Where can I find more information about the equation (Power=V^2/load)?

This is Ohm's Law. Search Google on that.

To compare two transmission lines, one at twice the voltage of the second, we need to consider various factors such as power losses, efficiency, and cost.

Advantage in terms of power losses: Higher voltage transmission lines experience lower power losses compared to lower voltage lines. This is due to lower current flowing through higher voltage lines, reducing resistive losses. Therefore, the line with twice the voltage will have lower power losses and be more advantageous to the utility company.

Advantage in terms of efficiency: Higher voltage transmission lines generally offer higher overall system efficiency. This is because they require less current to transmit the same amount of power, resulting in reduced I2R losses. Thus, the line with twice the voltage will have higher efficiency and be more advantageous to the utility company.

Advantage in terms of cost: Higher voltage transmission lines often require larger conductors and insulation, which can contribute to higher installation and maintenance costs. However, these costs are balanced out by the advantages of higher voltage lines, such as reduced power losses and increased efficiency. Therefore, the cost advantage of the line with twice the voltage would depend on specific factors such as the length of the transmission lines and other system requirements.

In conclusion, the line with twice the voltage would be more advantageous to a utility company due to lower power losses and higher efficiency. However, the exact quantitative advantage in terms of cost would depend on various factors and would require a detailed cost analysis considering the specific circumstances of the utility company.