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Directory:SHPEGS - Solar Heat Pump Electrical Generation System
The Solar Heat Pump Electrical Generation System (SHPEGS) utilizes a solar or geothermal powered absorption heat pump to improve the efficiency and location independence of SEGS/CSP solar thermal systems.
- http://www.shpegs.org - Published in Aug. 2006
How it Works
The idea is to leverage an available heat source to transfer much larger amounts of heat between the ambient air and the ground using a heat pump system. This heat source could be solar thermal, geothermal, coal or other waste heat sources. A convection tower (bi-directional chimney) allows the large quantities of air to move across the heat exchangers without expending energy as in a forced air system. A large subterranean heat storage system (water, sand, stone or earth, either natural or man-made) is used to store both the heat from the air and the heat collected from the solar/geothermal source until the air is cooler (either day/night cycle or seasonal). This stored heat is relatively close to the system (as compared to deep geothermal) and the energy to pump the heat is relatively low.
The system uses both a low boiling point fluid steam turbine and wind turbines in the tower to generate electricity.
This is an amalgamation of the SEGS, OTEC, Solar Tower, Water Spray Down Draft Tower, Low Temperature Geothermal and Shallow Thermal Storage ideas and has several fundamental improvements in efficiency, location independence and reliability over these systems when deployed separately. See the background page for more information on existing systems.
- A tower is built to allow large quantities of air to move across heat exchangers by natural convection without expending energy.
- Solar thermal or deep geothermal heat is used to power a heat pump which moves a much larger amount of heat from the air.
- Both the heat from the air and the heat powering the heat pump are stored in shallow heat storage and this is used to exploit the difference in temperature changes due to day time heating between the air and shallow underground, either day/night or seasonally. In effect this creates a local geothermal source and the low media transfer energy allows for an efficient geothermal power generation system. This source is reliable and may be used for base load electrical generation and structure heating.
Quoting from http://www.shpegs.org
- The solar or heat energy collected is used to move a much larger amount of heat from the air.
- The heat pump system can be powered from multiple sources (solar, geothermal or waste heat).
- The water spray evaporative idea can also be incorporated as a pre-cooler and would increase humidity prior to the cooling heat exchanger. This would improve efficiency and distilled water output.
- This system will be available in sub-zero temperatures and can generate as much power when it is really cold as when it is really hot.
- Due to the reversible cycle, the energy stored or removed from the earth is used in the opposing cycle.
- The system should be scalable from the single dwelling or remote equipment power source up to the MW grid project.
- The system is "tuned". The more heat transferred through the heat pump, the more convection occurs. The more convection that occurs, the more heat transferred through the heat pump. The more heat that moves the more mechanical energy that can be "harvested" and converted to electricity.
- The condensation on the cooling coils may be used to provide a clean domestic water source or for irrigation as a by-product during the air cooling cycle.
- The energy required to pump water to the top of the tower as in the water spray tower is eliminated and replaced with a heat pump system, both the heat from the air and the heat used to do the work of collecting it are stored in the ground.
- The system should operate in a wide range of climates with the limitation that there is sufficient solar heat above ground level and sufficient thermal transfer below ground level .
- A rotating or finned air intake/output leveraging prevailing winds would increase performance and it should also improve system startup.
- The system could be integrated with biomass methane production or with algae agriculture.
- Actively "cooling" the pumps, turbines and generators and using the heat will make it very efficient. (contributed by Mark Smith, September 2006).
- In colder climates where the ambient air temperature is below freezing for 6 months of the year, the system is really "renewable" because the amount of heat added and removed from the ground balances on an annual cycle.
- In some locations there are natural geothermal heat sources at deeper levels. The temperature gradient between deep thermal water at +40C and -30C winter air has a large potential power output.
No Patents / Open Source
Rohatensky has published his concept openly on the Internet, rather than pursuing a patent. He supplies the following reasoning.
Although this idea has huge potential and it could be exploited for personal gain, there are several reasons for putting this idea forth on the Internet.
- Economics. We are not running out of coal or uranium in the near future and we probably won't run out of oil prior to a normal patent expiry. A commercial venture into renewable energy is competing against these relatively cheap energy solutions and currently is not a very viable business. An example of this is the Athabasca Oil Sands. This is a scheme to extract oil from petroleum tar sand using large amounts of petroleum to extract, build infrastructure and construct processing plants and processing the sludge into oil takes huge volumes of natural gas. From the environmental point of view, this is insane. In reality the tar sand projects have been able to attract billions of dollars of investment, turned Fort McMurray into a boom town and are going forward very quickly. The reason that this type of mega-project is able to proceed is that it is still much more profitable than most renewable energy ideas. A new idea in renewable energy is priceless to society and worthless to an individual with a normal lifespan at the same time due to these types of projects. In areas without tar sands, renewable energy has a difficult time competing with coal or uranium.
- The construction of massive towers doesn't require petroleum. You can make a lot of pipe by melting down a Hummer. One has to look at pre-oil age construction techniques and materials that built the pyramids and the castles and cathedrals in Europe and not at modern oil based construction. Prior to 1900, everything was built without petroleum and lack of stones didn't end the stone age.
- To create a commodity out of this system as soon as possible. Competing against non-renewable energy takes a large amount of innovation, efficiency and in a very long timeframe renewable systems will not run out of fuel and prevail over non-renewable systems. It is very difficult for a single commercial venture to sustain operation until that time.
- The principles and project management of Linus Torvalds with Linux and the many other contributors to Open Source and Free Software have shown such success with large projects. This actual construction of this type of project is very different than software, but the concept and design of the system can be managed the same way as open source software and show the same rapid development of new ideas.
- There are many people with good ideas and a willingness to help, but Mechanical and Electrical Engineering and Physics are not their field. In this type of project, there are social, economic, environmental, political, information technology and financial tasks and the engineering and construction of the system is actually a small portion of the development and deployment. The project spirit is based on bringing people together to work on something that has benefit for everyone.
- People want to live in a world where there is clean, cheap energy and they will help to bring that about.
- Solving the problem, not getting rich. We don't have a practical alternative to fossil fuels because most people and companies are trying to make a lot of money solving the problem. They concentrate too much on the financial gains and not enough on solving the problem.
- Energy is fundamental to modern society and should be owned by the people not the corporation. People have morals, corporations have responsibilities to their shareholders to show large profits.
- Although the entire project is being managed in a not-for-profit manner, the intent is to work with business. The detailed design, manufacture of the sub-assemblies, construction, system operation and integration with existing operations and waste heat sources can create many economic opportunities.
I learned very early and painfully that you have to decide at the outset whether you are trying to make money or to make sense, as they are mutually exclusive. --- R. Buckminster Fuller GRUNCH of Giants, 1983
Contributed Improvements to Displayed Design
2006-08-28 (Danny Mc Menamin) - Phase Change Material could be used as the secondary media rather than the earth.
In the News
- Open Project to Develop Renewable Energy System - "We have been working on a system that combines some existing indirect solar technologies to build a location independent, renewable, reliable and economically feasible indirect solar electrical power generation system." (Slashdot; Jan. 8, 2007)
See Discussion page
The quotations from Rohatensky's website are with permission. Rohatensky first posted this page here, and has contributed to its development and dialogue.
Robert J. Rohatensky