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.
Renal calculi: Kidney stones. A common cause of blood in the urine and pain in the abdomen, flank, or groin. Occurs in 1 in 20 people at some time in their life. Development of the stones is related to decreased urine volume or increased excretion of stone-forming components such as calcium, oxalate, urate, cystine, xanthine, and phosphate.