Industrial Ecology is the study of the natural resource flow through an industrial system used to create a product and carry it through its life cycle. The objective is to incorporate principles of natural ecosystems where byproducts of processes including resource allocation, production, operation, maintenance, and end-of-life are used as feedstocks for other processes to where they function harmoniously with ecological systems.
Many early industrial systems effectively used process byproducts and residuals for power and operated within the short carbon cycle. The short carbon cycle is the carbon moving around between the atmosphere, oceans, soils, plants, and animals. As the 20th Century progressed, fossil fuels and utility energy systems, which offered the user greater convenience and lower capital cost, displaced many on-site combined cycle systems. Fossil fuels are made of carbon that comes from the gradual deposition of short carbon cycle material into subterranean carbon vaults and comes back into interaction with the short carbon cycle naturally via volcanoes and erosion. The extraction and utilization of fossil fuels bypasses the natural way carbon is reintroduced at a rate that exceeds the capability of ecological systems to sequester it.
Some remote industrial systems built in the late 20th Century continued to follow earlier practices due to fossil energy scarcity, unreliable infrastructure, utilization of a renewable fuel if harvested on a sustained yield basis, and cogeneration to increase the overall efficiency and economic viability of the system.
An example of a late 20th Century combined-cycle coconut oil production system in Fiji which uses coconut husks as boiler fuel.Vapor Motive Company specializes in utilizing biomass residuals for combined cycle systems:
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There are challenges in the amount of energy we consume. A large portion of this energy has to do with the poor efficiency of industrial and consumer energy systems in their energy use and lack of energy conservation. Mobile and small-scale stationary systems often are the least efficient and yet still require the highest-grade energy sources such as diesel fuel delivered to locations that are often remote. Using the most efficient and practical type of energy for a job and combined cycle and waste heat utilization with highly serviceable components made from low impact raw materials and designed to last decades are primary focuses of Vapor Motive Company’s designs.
Note: Assumes national averages for grid electricity and incorporates electric transmission losses.Source: Tina Kaarsberg and Joseph Roop, “Combined Heat and Power: How Much Carbon and Energy Can It Save for Manufacturers?”
Thermal cogeneration (CHP) remains one of the most efficient forms of energy production. In the above example, a process requires 30 units of electricity and 45 units of thermal energy. Separate energy systems require more energy input to provide these energy units because the generation of electricity from a stand-alone thermal plant is low (example 32%). In a CHP system, the waste heat of generating electricity is recovered and used for a thermal process (example 45 units.) In a steam cogeneration system such as the copra dryer example, the steam generated by the boiler is used twice; once as a high-pressure steam to drive the steam engine and then the latent heat of vaporization of the low-pressure steam is used to dry the product and the fuel. Where a boiler fuel is available as a byproduct from a process, such as the copra dryer example, no external energy to the production process may be required.
The 20th Century also saw the development of effective solar thermal collectors for generating steam and hot water. Though hot water systems can supply a large amount of process requirements, steam or higher temperature thermal fluid is often needed as well as mechanical power or electricity. While fossil-fuel scarcity in remote locations inspired initial development, disruptions in the fossil-fuel supply chain in the U.S. in the early and late 1970’s spurred a variety of projects and political interest.
It should be noted that an environmental awareness has long been associated with solar thermal collectors:
“One thing I feel sure of and that is that the human race must finally utilize direct sun power or revert to barbarism. I would recommend all far-sighted engineers and inventors to work in this direction to their own profit, and the eternal welfare of the human race.” – Frank Schuman, Scientific American, 1914
“In many places, solar heating is as economical today as power from nonrenewable sources. Nobody can embargo sunlight. No cartel controls the sun. Its energy will not run out. It will not pollute our air or poison our waters. It is free from stench and smog. The sun’s power needs only to be collected, stored, and used.” – President Jimmy Carter, May 3, 1978 – Sun Day
Integrated solar thermal and photovoltaic arrays for facility at mid-latitude with a thermal process
VMC’s solar trough design allows rooftop mounting to lower land requirements, reduce transmission losses, and provide some shade below them. There are a lot of opportunities to optimize a building, and those should be studied in the book, “A Golden Thread, 2500 Years of Solar Architecture and Technology” by Ken Butti and John Perlin.
It is possible to implement a CHP system with direct solar energy:
Combined cycle freeze desalination system powered by solar thermal micro troughs with steam engine generator and water as refrigerant
In the diagram to the right, one cylinder bank of the exhaust of the steam engine generator provides the motive steam for an ejector which is pulling a vacuum on an evaporator in a vacuum freezing desalination process as well as feedwater heating and brine effluent evaporation. The other cylinder bank of the steam engine’s cylinders is exhausting to a condenser. A Balance Control Module indicates each cylinder in real-time and controls the independent cut-off control of each cylinder bank.
In this diagram, the process requires 45 units of thermal energy and 5 units of electricity. Providing this primarily thermal process would require 383.5 units of aperture with PV, but only 100 units of aperture of VMC parabolic troughs.
“Steam is the alternative electricity.” –
Bill Petitjean, P.E.
VMC steam engine drive cylinders installed on contemporary reciprocating compressor frames for power and process applications provide needed solutions to decarbonize renewable energy production. The contemporary separable process compressor has developed from integral steam engine compressors common until the 1960’s to utilize higher speed internal combustion and electric prime movers which typically derive their energy from fossil fuels. Transitioning to renewable energy resources, which typically are of a lower grade energy and more transient in nature, recalls the steam engine back to duty as a prime mover. Utilizing a contemporary reciprocating compressor frame for an integrally-driven steam-driven compressor or equipping it with a full complement of steam drive cylinders for a steam engine prime mover as well as the knowledge gained by the reciprocating process compressor industry allow the steam engine to be rapidly and effectively deployed in a cost-effective manner to help facilitate energy transition.
The steam engine is a well-established prime mover that was gradually displaced by other technologies that were less capital intensive to the end user and offered them a higher energy convenience standard. These technologies, such as internal combustion and electric motors also provide a lower cost per unit of energy, provided the economic analysis does not account for the typical sourcing of their energy from long carbon cycle (fossil) inputs and dumping this carbon into the short carbon cycle environment (the atmosphere). Modern production methods combined with gains in knowledge of cylinder tribology, fluid dynamics, and mechanical design make the VMC reciprocating steam prime mover competitive when using a renewable resource as it is functioning as a concentrator of relatively low-grade thermal energy to high grade mechanical energy with the potential to be carbon neutral or function within the short carbon cycle.
The steam engine is viable as a prime mover for contemporary applications in distributed power and renewable energy applications including solar thermal, waste heat, geothermal, and biomass. It can play a critical role in the decarbonization of hydrogen compression, natural gas compression, CO2 sequestration, as well as the production and upgrading of feedstocks for hydrogen production by converting low-grade renewable energy inputs into high-grade mechanical power for processes.
The VMC steam drive’s reliability, adaptability to variable loads, variable steam conditions, and variable speeds is unmatched in prime movers.
VMC’s 5” stroke frame design provides the opportunity for a high torque, variable speed direct drive application without the capital cost and losses associated with electric drives and transmissions. The engine features a standard SAE bellhousing for direct connection to many types of power equipment. When thermal energy can be acquired from solar, geothermal, biomass, and waste heat and steam produced, the VMC steam engine offers the opportunity to use this energy directly rather than incur the inherent losses of electric generation, transmission, motors, and speed controls.
Steam Compression
Steam compression is the process of upgrading low-pressure steam to a higher temperature and pressure preserving the latent heat of steam vaporization of the low-pressure steam. The energy required to upgrade this steam may have a coefficient of performance exceeding ten versus generating new high-pressure steam. Mechanical vapor recompression of steam involves a two-phase process. First, liquid is removed from a pressurized process by a steam trap then exhausted to a mechanical separator at a lower pressure and flashes to steam. This steam can then be recompressed to a valuable higher pressure and temperature.
Challenges for steam compression include controlling the quality and temperature of the steam being compressed and utilizing materials suitable for steam and the shock loads typical of a reciprocating compressor handling a two-phase fluid. Opportunities currently exist for both centralized and decentralized steam compression. For instance, steam may be recovered from various processes and pass through a low-pressure piping system to a header for a centralized compressor. VMC is developing small compressors that recompress steam at the process vessel trap and discharge it to a local high-pressure header, thereby avoiding expensive large diameter piping and thermal losses.
Materials
VMC’s machine designs draw on traditional steam materials such as cast iron, bronze, and steel which are not rare and highly recyclable. Special coatings are used to modify cylinder tribology for increased wear resistance and minimize lubricant use. Easy-to-replace wear components allow for multiple overhauls in the field to enable decades of use.
VMC can help you with tools your industrial energy system needs for gathering, concentrating, and recycling thermal energy for mechanical work and heat processes. This contributes to the larger picture of designing flows of materials and energy in industrial and consumer activities so that they achieve a sustainable, renewable, or regenerative mode of operation compatible with the biosphere.