Re: What has more energy solid ice at 0c or liquid water at 0c?

If you have ice at 0 C, you need to add heat to melt it to water at 0 C. 
Conversely, if you have water at 0 C, you need to remove heat to freeze it. 
So, even though ice and water can both be at 0 C, water contains more 
energy.

If you want to get quantitative about it, water has a "molar heat of 
fusion" of 1.436 kcal/mole. Translated, that mean that it takes about 1 1/2 
Calories (a food Calorie is a chemist’s kcal or kilocalorie) to melt 18 
grams of ice (a bit more than half an ounce).

You can learn more about the relationships between energy and melting/
freezing by consulting any high school or college general chemistry text 
book.