SpinOffs

There is obviously a huge amount of interest in Supercritical Carbon Dioxide (sCO₂) within the energy industry. One reason is because sCO₂ Brayton power cycles operate in the same way as other Brayton cycles, but with a much higher power density. This has the potential for greatly reducing the size and cost of equipment. Additionally, efficiencies can reach as high as 40% for an sCO₂ system, compared to about 33% for a typical heat recovery system. 

Have you ever been to the beach on a very hot day? Then I am sure you noticed that the sand is very, very hot, uncomfortably so. Congratulations, you have had first-hand experience with ground source energy storage! Now, as you were hopping across the burning sands, seeking out tufts of grass to cool your burning feet, did you ever wonder how to harness the energy stored in the sand? I have, because it’s too hot for me to read on the beach and sand is a great place to draw diagrams and write equations.

Who has not dreamed of living on an island? You’re getting away from it all, walking alone along a secluded beach, as the ocean gently laps at shore…ahhhh. Excuse me – I have to go search for vacation packages!

OK, I’m back. Ironically, the very thing that attracts people to islands is the same thing that makes them a nightmare to live on when disasters strike - being “cut off” from the mainland. A recent example is Puerto Rico, where Hurricane Maria roared through with 190 mph winds that completely wiped out the power across the island. Well over a month later, most of the island is still without power and clean drinking water is in short supply. It will take years for the island to recover.

There are not many people who would argue that if you only received 30% of a commodity that you need to purchase every day to enable you to have your share of “…life, liberty and the pursuit of happiness”, then you should have some recourse to get the rest of your order or some money back. However, each day, everyone in the United States and throughout the world purchases energy. The availability of a ready source of affordable energy is one of the criteria for a country’s industrial economy and the prosperity of its citizens. Every engineer learns very quickly that not all the energy you pay for can be transformed into useful form. The engine in the transport vehicle that brings you to work is likely to have an efficiency as low as 25%. The hot water for the lavatories in your office building has been heated with a much more respectable efficiency of 80-90%, at least according to the First Law of Thermodynamics.  However, if your office building is heating water to only 105-110°F, using a fossil fuel-fired furnace, then the Second Law of Thermodynamics can be used to determine the second law efficiency to be only 15%. In contemporary engineering thermodynamics terms, you’ve increased the entropy of the universe. In contemporary layman’s terms, you’ve been robbed!

While common sense might lead one to conclude otherwise, increasing energy consumption worldwide is a good thing. Higher per capita energy consumption is associated with a higher quality of life: electricity for home appliances, transportation, affordable heating, lighting and so on. On the other hand, there is and should be enormous concern about the type of energy being used to fuel this increased consumption stemming from issues such as environmental impact, national security, etc.  

Expanding design capabilities for advanced high-performance turbines for steam and organic Rankine cycle power generation is a constant area of focus in developing Concepts NREC’s Agile Engineering Design System ® (AEDS) software.

Cycle and operation requirements, as well as a wide range of operating conditions and volumetric flows, are often required for the design of turbines with diverse geometries. Some typical design tasks and available new/existing features within AEDS are described here.

Concepts NREC introduces licensing for its new compact, high-speed, hermetically sealed turbogenerator. Nominally rated for 300 kWe, the CN300 is designed for converting low temperature heat to electric power using an Organic Rankine Cycle (ORC) process.

Historical Perspective
Increasing concerns for protecting the environment and the escalating cost of energy itself have raised interest in energy conservation to an all-time high. This interest extends to waste heat recovery systems. These systems produce electric power by converting thermal energy to electrical energy. And, when site conditions involve temperatures too low for conventional heat recovery systems, ORC processes become the best solution. These are typically defined as any heat source at temperatures below 800oF. In fact, according to one U.S. Department of Energy report, there could be as much as 1.5 to 2.0 quadrillion BTU/year of heat with temperatures below 500^oF available from exhaust gas streams in the industrial sector alone. Naturally occurring heat sources may be just as plentiful.