Why was Britain geographically lucky when it came to a new source of fuel?

Britain has the largest coal reserve in Europe.

Explanation:

During the earlier era of the industrial revolution, Coal was the primary source of energy fuel that people use to power their cities, factories, vehicles, etc.

Having the largest coal reserve means that Britain could make all the production/manufactures in the country become significantly cheaper. When they sell their products to the international market, this will resulted in higher profit for Britain.  As a result, Britain become the most prosperous nation during the earlier era of Industrial Revolution.

equal area projections

equal-area projection. a projection in which regions on the earth's surface that are of equal area are represented as equal.