40 years to pay for itself? that doesn’t seem very impressive. Am I wrong?
I doubt the payback is 40 years. While the article is unclear, it notes that the city is pay 3.2M versus 7M, the difference of which appears to have been used to calculate the 37.9 year number in post 1.
That would be only the city's savings.
The article also notes that the city and surrounding county (population ~80k) are involved. That indicates other revenue sources are likely involved and that the cost effectiveness and payback period is not limited to the financial aspects the city has noted.
I'm not sure how this system works specifically, but it appears to be a district energy system. Such systems can be highly efficient. Generate high pressure / temperature steam, use some of it's energy to generate electricity and distribute the lower energy steam for district heating purposes. Chillers can use that steam during times when cooling is needed through steam driven chillers.
Actually, this kind of set up is not new and is used by multiple cities, frequently on large campuses, and in various industrial settings. Buzz words include cogeneration, etc.
Problem is - in the US - if you want to burn, use, incinerate, anything that might be considered trash you'll have massive regulatory requirements that will push that $144M much higher...