Applying the first law of thermodynamics - What do you think about dark energy as a new energy source?

Suppose we understand the nature of dark energy at some point in the near future. Wouldn’t this offer a new, smart and clean source of energy to tap into? Why bother with solar energy or cold fusion? Dark energy seems to be the reason for the accelerated expansion of the universe. And there’s plenty of it out there. Couldn’t we apply the first law of thermodynamics? Slowing down the expansion just a tiny, tiny little bit and power a generator for electricity supply? A bit like gravitational slingshots or gravity assists when using space probes (which is proven technology today). We have successfully slowed down the rotation of Jupiter to accelerate space probes on their way to Saturn.

From Wikipedia: In physical cosmology, astronomy and celestial mechanics, dark energy is a hypothetical form of energy that permeates all of space and tends to increase the rate of expansion of the universe. Dark energy is the most popular way to explain recent observations that the universe appears to be expanding at an accelerating rate. In the standard model of cosmology, dark energy currently accounts for 74% of the total mass-energy of the universe.

Two proposed forms for dark energy are the cosmological constant, a constant energy density filling space homogeneously, and scalar fields such as quintessence or moduli, dynamic quantities whose energy density can vary in time and space. Contributions from scalar fields that are constant in space are usually also included in the cosmological constant. The cosmological constant is physically equivalent to vacuum energy.

http://en.wikipedia.org/wiki/Dark_energy