PacSci-Doku: “Drought Buster”

By Dennis Schatz – Senior Advisor

Do you Sudoku? It’s one of the hottest number games around! Well, here’s a twist we think you’ll love. We call it PacSci-Doku. Can you guess why? Here’s how it works. Instead of filling in the blanks with numbers, we use letters. Hidden in one of the columns or rows is the answer to a science question. We then provide some information about the answer on the answer page for the PacSci-Doku. The question in this edition is:

What may help solve California’s drought?

To find the answer, complete this PacSci-Doku using the following nine letters:

E e A a _ t S r w

Each row and column in the grid below has to have only one of each of these letters. Each of the 3 x 3 mini-squares in the 9 x 9 square also needs to have only one of each letter.

PacSci-Doku: "Drought Buster"

Puzzle Difficulty=Medium

The question in this edition is:

What may help solve California’s drought?

The answer: Sea Water

PacSci-Doku Drought Buster Answer


Drought in California has put fresh water in limited supply. But being on the Pacific Coast, California has access to a nearly unlimited supply of water – unfortunately it’s salty. San Diego County is now planning to tap into that sea water by building the largest desalination plant in the Western Hemisphere. Desalination is a major way to get fresh water in other parts of the world, especially the Middle East. Israel will soon get half of its fresh water from the sea.

The new plant in San Diego will produce 50 million gallons of drinking water each day, enough to supply about 7 percent of the county’s needs. But this fresh water comes at an expense. It will cost customers about $5.00 more per month, and raise a number of environment issues – where to put the salt extracted from the sea water, and how to deal with the increased CO2 – which increases global warming — caused by the required energy to operate the plant.

The high energy is needed to force the water through a sieve-like membrane that can let the smaller molecules of water through, but not the large salt molecules. In the future, the hope is that the increasing use of wind and solar power will provide much of the energy – thus eliminating any CO2 emission — especially since the production of water can be timed for when there is an excess of solar and wind power.

Read more about California’s plan to use desalination to combat its drought.