If energy in the universe is constant, why is the world yelling out for energy crisis? What does judicious use of energy imply?

Whether the energy in the universe is constant or not is not particularly pertinent. The crisis has to do with how much energy on this planet can be found in a form easily converted to gasoline and other petroleum products upon which we've based our vehicles and energy-delivery infrastructure. Solutions to the crisis abound. For instance, the small fraction of energy from our sun that intersects with our planet is more than enough to power all human society. But it would require a great investment in new infrastructure – as would most alternatives.

This is because not all the energy  in the universe is in a form which can be used by humans. We cannot do anything useful from random molecular motion or radiation directly. We can convert some of the thermal energy into work but there are theoretical limits to how efficiently we can do that and it is much less than 100%. When people talk of energy crisis, they mean they are running out of resources which have sufficient energy stored in their chemical bonds that can be harvested first to produce 'heat', which can then be further utilized to do some useful work like running a turbine  to produce electricity. Much of the energy of the universe is condensed in the form of mass itself, but there are only a few rare minerals from which we can destroy some of its mass to produce equivalent energy in a profitable way (nuclear fission). So yes, energy crisis is a real concern for mankind and not a conspiracy of scientists to dupe the  public.

http://www.multivax.com/last_question.html Energy isn't enough. For the energy to do useful work, you need to increase the entropy of the universe. See the heat death of the universe above. That's not really the problem, though. The problem is that we're addicted to cheap energy. Scarcity and environmental catastrophe are threatening that cheap supply, all while demand continues to surge. The rise of third world standards of living and populations is generating new consumers, and the development of new technologies is finding ever more use for energy. While interest in efficiency is growing, demand is growing much faster. Bad politics and oil conglomerates make finding alternative supplies more difficult. Government subsidies of oil shelter consumers from the true cost of their lifestyles, preventing change. Fear mongerers and yellow press keep nuclear energy from taking off, even though it's the most viable alternative. Everyone refuses to make compromises on the issue, so we keep putting it off with half-measures and empty promises. Eventually things will get so bad that procrastinating will no longer be an option. The energy crisis is first and foremost a social problem. There are solutions now, but they all have tradeoffs.

The energy crisis stems from the fact that we are mostly dependent on non-renewable energy sources, like coal. As worldwide energy consumption rises, and the amount of coal left in the earth decreases, we are looking at a grim future for societies who are near total dependency on technologies like electricity and gas-powered vehicles. The judicious use of energy is basically being smart about how we use our limited resources to stretch them as far as possible, particularly until research produces better ways of harvesting renewable sources of energy, like solar and wind power. Bonus fact: it has been estimated that if we were able to harvest 100% of solar radiation, we could collect in one minute what the entire world is using in an entire year. This is probably simplistic at best, but effectively demonstrates the great potential of solar power.

Judicious use of energy means instead of clapping for that epic dialogue that Tony Stark just made, I should clap for a transducer that charges my phone. So, even if energy is constant, the energy that's available should be converted to those forms of energy that have more priority.

There are two forms, Low grade and High grade energy. High grade energy can be utilized and converted from one form to the other efficiently, whereas, Low grade energy cannot. Any action we perform, we create heat, which is a Low grade energy. So, no doubt, energy remains constant but there's more Low grade available than High grade.

Energy in the universe is constant -True, but remember energy is not always available as energy itself. Remember Einstein's E=mc^2? Energy can be converted to mass and vice versa, and also energy can exist in various other forms in the universe which cannot be tapped and utilised for human needs. The main source of human usable Energy is Fossil fuels(presently) which are running low of late and thats the reason the world is yelling about energy crisis!!!

When we talk of useful energy we talk abt high grade energy, bcoz high grade energy is the one from which we can obtain large amount of work. Electrical energy is a form of high grade energy while heat is low grade energy