Terrajoule systems are based on technologies with proven high reliability. They are modular, with few or no single points of failure.
Here are the key elements of Terrajoule systems and their reliability profiles:
- Steam Engines. Steam engines powered the Industrial Revolution and were highly evolved for reliable operation. Long-term US Navy data showed that marine steam engines had a useful life of as much as 30 years under continuous operation. As an ongoing example, the SS Badger has been plying Lake Michigan daily for 60 years. It is powered by 7,000 horsepower of Skinner Unaflow steam engines, the same core engine technology on which Terrajoule systems are based. Steam engines are simpler than internal combustion engines, and generate no combustion products to cause corrosion and wear. The majority of bearing surfaces are fluid film. Note that unlike most internal combustion engines, in a Terrajoule steam engine there is no contact between the pistons and the cylinder walls, due to its double-acting configuration. Terrajoule steam engines are designed for a minimum of 25 years continuous operation.
- Energy Storage System. The energy storage system is based on steel pressure vessels containing water. The water is in a closed system and is maintained to a fully non-corrosive chemistry. The energy storage system has the same physical structure and similar operating conditions as a “steam accumulator”. Steam accumulators have been used for many decades to reduce the costs of industrial steam plants, so their longevity is well known. There are no cyclic fatigue or corrosion issues for a well-managed system. A useful life in excess of 25 years is assured.
- Solar Concentrator System. Solar concentrator systems have been in continuous operation for over 30 years, with a steadily increasing reliability.
Operations & Maintenance (O&M)
Terrajoule systems are fully automated for unattended operation. Further, a constant monitoring system can diagnose possible failures before they become a problem. This diagnostic technology allows for planning of repairs and a reduction of unscheduled down time. These modern computer and sensor technologies place Terrajoule distributed steam plants in a different category than the steam plants of decades past, which required skilled operational labor on site.
Mirror cleaning must be done to maintain maximum operational efficiency. The frequency and cost of such cleaning varies with the location. Terrajoule forecasts total annual O&M cost less than 1% of system capital cost in most applications.