Solar Stirling Generators

Clean and renewable energy for Glenforest

Bringing Tomorrow's Technology Today

Renewable energy is the future. Fossil fuels are limited, and sooner or later they're going to run out. Moreover, they are terrible for the environment because they emit greenhouse gases such as carbon dioxide, among other pollutants. Although we are still a ways off from being able to meet our energy needs through renewable sources alone, every little bit helps and everyone should do their part to become part of the solution.
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Benefits of Renewable Energy

  • Clean, no pollution apart from manufacturing the materials
  • Decreases dependence on fossil fuels
  • Provides free energy
  • Governments offer tax rebates
  • Leaves a sustainable land for future generations


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Why Stirling Generators at Glenforest?

Hydroelectricity


  • Glenforest is not located near a source of water
  • The project would require government approval
  • It may disrupt the local ecosystem


Wind Energy


  • Glenforest is not located in a particularly windy area
  • The land surrounding Glenforest is not flat and open
  • Glenforest does not have the land area to support such a project


Photoelectric Solar Panels


  • The initial setup cost is far too expensive for a public school ($20-30K for a residential house)
  • The technology is relatively inefficient compared to other options
  • Electricity is expensive to store in large quantities when the sun doesn't shine



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Solar Stirling Generators


  • Glenforest has a flat roof with a large surface area that would be perfect for a solar stirling generator
  • Stirling engines operate on heat, not light, which is much cheaper to store
  • They are more efficient than solar panels
  • Stirling engines operate on a temperature difference, so they will actually be more efficient during winter
  • The initial setup cost is cheaper than photoelectric solar panels
  • They're very reliable and require little maintenance
  • A single dish can produce 25kW, which is enough to power about 10 homes
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How Everything Works

What is a Solar Stirling Generator?

A solar stirling generator is a type of electric generator that converts solar energy into electricity.


It's essentially made up of three basic components:

  • A parabolic reflector to concentrate the heat
  • A stirling engine to convert heat into motion
  • A generator to convert motion into usable electricity


It utilizes a parabolic reflector to focus the Sun's rays onto a stirling engine, which transforms the heat energy into mechanical energy, and a generator coverts the mechanical energy into electrical energy.


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How a Parabolic Reflector Works

Parabolic reflectors reflect all of the incoming sun's rays towards a single point. By doing this, parabolic reflectors can generate extremely high temperatures over a tiny area, which is perfect for powering a stirling engine.


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How a Stirling Engine Works

A stirling engine is hot air engine that drives a flywheel by converting heat energy into kinetic energy. It consists of a sealed cylinder with two pistons, heated at one end and cooled at the other. One of the pistons is a displacer piston that moves the air from the hot to the cool end, and the other is a power piston that drives the flywheel.
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Step 1

A heat source (in this case sunlight) heats one end of the cylinder


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How Electricity Is Generated

  1. The flywheel of the stirling engine is connected to the driving axle of the generator
  2. The rotor, which has several magnets on it, spins
  3. Electric current is induced in the solenoids according to the Faraday-Lenz laws
  4. The alternating north and south poles of the spinning magnet produces AC current
  5. Load can be added or taken off the circuit to adjust the resistance
  6. The resistance is changed to keep the rotor spinning at a constant rpm to maintain the electricity at 60 hertz
  7. The electricity is converted to 120 volts via a transformer
  8. Now the Solar Stirling Generator can be used to power anything that runs off of a wall outlet!


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Making Dreams a Reality

Implementing the Solar Stirling Generator

Solar stirling generators are great, but to actually put them to use requires a lot of careful planning, and costs a lot of money. Many things must be carefully considered, for example:


  • The size of the dish used - is it better to use a single large dish or an array of smaller ones?
  • The location - would the roof be able to support the dish or will it need to be placed in the field?
  • Funding - how will the school pay for this project? Will it come from the school board or the city?
  • The amount of electricity needed - how much electricity will need to be produced? Will this take into account future needs as well? Will the generator supply all of the school's needs or simply supplement them?


These are all important and practical questions that would need to be solved in order for this project to be feasible. Despite the difficulties, the rewards of a solar stirling generator, if successfully implemented, should repay the costs several times over.

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Companies

While solar stirling dishes have traditionally been undertakings by large companies or even cities, there are some innovative companies who are offering solar stirling solutions on a smaller scale. One of these is Infinia, which produces single dishes as small as 3.5kW.


Solar Stirling Generators In Action

Stirling Dish 500MW solar power plant
Here's a great example of how solar stirling generators are being used by the city of San Diego to replace fossil fuels as their primary source of energy.