Stirling engine micro-CHP This technology is new to the market, although the principal of the Stirling engine is well established. The electrical output is small relative to the heat output (about 6:1) but this is not necessarily a problem for micro-CHP.
1 Kidney pain and back pain can be difficult to distinguish, but kidney pain is usually deeper and higher in the back located under the ribs while the muscle pain with common back injury tends to be lower in the back.  Causes of kidney pain are mainly urinary tract infections and kidney stones.
Back pain could be a sign of a kidney infection. Lower back pain can be debilitating. Finding the root cause of it can be nearly as frustrating. Part of the reason is the complexity of the human muscular-skeletal system, and the fact that so many stresses from our erect posture can come home to roost in our lower backs.