More and more companies have begun to consume less energy by making

Main conclusion is a call for action or statement of opinion. It can also be a hypothesis.
Whether a statement is the main conclusion of an argument depends on what else is given in the argument.


Argument 1: More and more companies have begun to consume less energy by making themselves more efficient. They have started using energy efficient machines and installing solar panels in their premises. Over time, these efforts could place the United States at the forefront of an emerging global market for cleaner technologies.

Main Conclusion: Over time, these efforts could place the United States at the forefront of an emerging global market for cleaner technologies.
This is the author's opinion.


Argument 2: More and more companies have begun to consume less energy by making themselves more efficient. Over time, these efforts could place the United States at the forefront of an emerging global market for cleaner technologies. Such efforts are also essential to tackling the two big energy-related issues of the age: global warming and the dependence on precarious supplies of oil. The federal government should encourage these efforts by providing the necessary incentives, whether as loans, direct grants or targeted tax breaks.

The first 3 sentences tell us that these efforts are important.
Main Conclusion: The federal government should encourage these efforts by providing the necessary incentives, whether as loans, direct grants or targeted tax breaks.

The first 3 statements explain WHY the federal govt should encourage these efforts. Not the other way around.

Hence 'federal govt ...' is the main conclusion.