The interwoven nature of water and energy in California will undoubtedly grow more complex -- and strained -- in the years to come.

We've been following some of the issues related to the drought in California. In response to water shortages, a "water bank" has been implemented to allow users who do not use all of their water to sell it to other users. In theory, such a system allows water to be used in an efficient manner, with higher priority users gaining the ability to purchase water when there are shortages.

In looking at the reality of implementing such a system, however, it becomes clear that there are challenges on many levels. This is evidenced by the fact that despite the state's efforts, it will likely only promote the trade of 82,000 acre feet of water this year -- less than 15% of what it had been hoping for.

One major challenge is related to the price of food crops, which have risen drastically in the last year, making the sale of water less appealing to farmers. Additionally, there is the fundamental challenge of getting the water where it needs to be once it has been purchased, a task that requires vast amounts of energy.