Hint: People burn this
The answer to this puzzle is:
1. ALCOHOL
2. CALORIE
3. LEAVES
4. HYDROGEN
5. FIREWOOD
6. INCENSE
7. GASOLINE
8. PLASTIC
9. BARBECUE
10. FIELD
11. EVIDENCE
12. SAVANNA
2. CALORIE
3. LEAVES
4. HYDROGEN
5. FIREWOOD
6. INCENSE
7. GASOLINE
8. PLASTIC
9. BARBECUE
10. FIELD
11. EVIDENCE
12. SAVANNA