Clean Eating With A Slow Cooker: Hot 3 Bean Casserole

My co-worker's husband makes this 3 bean casserole every month or so, and it is a favorite "Can I have a taste??" foods for my boss to nab. She sent me a link for the recipe; it comes from an old cookbook her husband has, but she found it on the TLC website as well: Hot 3 Bean Casserole.
It is very good served as a side dish with something like meatloaf, or even as the main protein for your meal.

Hot 3 Bean Casserole

2	tablespoons olive oil
1	cup coarsely chopped onions
1	cup chopped celery
2	cloves garlic, minced
1	can (about 15 ounces) chickpeas, rinsed and drained
1	can (about 15 ounces) kidney beans, rinsed and drained
1	cup coarsely chopped tomato
1	can (8 ounces) tomato sauce
1	cup water
1	to 2 jalapeño peppers, minced
1	tablespoon chili powder
2	teaspoons sugar
1‑1/2	teaspoons ground cumin
1	teaspoon salt
1	teaspoon dried oregano
1/4	teaspoon black pepper
2‑1/2	cups (10 ounces) frozen cut green beans
The night before you wish to make this, heat the olive oil in a skillet and saute the onion, celery and garlic until tender. Put in the fridge for use the next morning. Add all remaining ingredients in the crock pot with the onions/celery/garlic from the night before and cook on low for 6-8 hours.