Keeping the Lights on When the Sun Disappears
A spinning solution for green energy
Renewable energy is the future. However, while conventional power plants use turbines to even out any fluctuations in supply and demand, most renewable energy sources lack these. A flywheel can provide the solution. And this operates under vacuum, generated by a vacuum pump from Busch.
Inertia. An important physics concept that allows us to ride a bicycle without falling off when we stop pedaling, and that makes sure the car keeps going even when our foot lifts off the accelerator. The same concept applies in power plants. In a coal power plant, for example, coal is burned to vaporize water. The steam this produces is used to drive turbines at hundreds of rotations a minute, each rotating constantly at exactly the same frequency – the frequency of the power grid they supply. Conventional power plants are designed and sized to generate a constant amount of electrical energy, and these turbines mean that they are capable of levelling out fluctuations in energy demand. This is what ensures that our power grid remains stable and that our lights stay on.
The renewable problem
Every time power is drawn from the grid, even just when a light is switched on, the frequency drops. The grid must be able to compensate for this change in frequency, or risk lights that flicker and devices that don’t operate properly. While simply annoying at home, frequency drops can be life-threatening in other situations, such as in hospitals.
However, renewable energy is, by its nature, variable. The sun disappears behind a cloud, the wind drops, the tide goes in and out, there are periods of low rainfall. And since most methods do not drive turbines that can stabilize their supply, these greener sources can cause problems for the grid.
A frictionless solution
Renewables like solar panels generate direct current. The power grid, on the other hand, operates on an alternating supply. The current the renewable sources supply must therefore first be converted using an alternating current converter. However, the issue of their variability remains. One method of stabilizing the input from renewable energy is by using a large, heavy wheel, called a flywheel. The electricity generated is used to keep this flywheel spinning, in the same way that steam would drive a turbine. To ensure that the flywheel runs smoothly and loses an absolute minimum in kinetic energy due to friction, it is kept under vacuum.
If demand for power increases, or the power generated by the renewable energy sources drops, the grid then draws the energy from the wheel. The inertia of the flywheel allows the energy to be transmitted at the same frequency for a short period of time – just long enough for other power sources to react to the power deficit and pick up the slack, ensuring that the grid remains stable.
The renewable problem
Every time power is drawn from the grid, even just when a light is switched on, the frequency drops. The grid must be able to compensate for this change in frequency, or risk lights that flicker and devices that don’t operate properly. While simply annoying at home, frequency drops can be life-threatening in other situations, such as in hospitals.
However, renewable energy is, by its nature, variable. The sun disappears behind a cloud, the wind drops, the tide goes in and out, there are periods of low rainfall. And since most methods do not drive turbines that can stabilize their supply, these greener sources can cause problems for the grid.
A frictionless solution
Renewables like solar panels generate direct current. The power grid, on the other hand, operates on an alternating supply. The current the renewable sources supply must therefore first be converted using an alternating current converter. However, the issue of their variability remains. One method of stabilizing the input from renewable energy is by using a large, heavy wheel, called a flywheel. The electricity generated is used to keep this flywheel spinning, in the same way that steam would drive a turbine. To ensure that the flywheel runs smoothly and loses an absolute minimum in kinetic energy due to friction, it is kept under vacuum.
If demand for power increases, or the power generated by the renewable energy sources drops, the grid then draws the energy from the wheel. The inertia of the flywheel allows the energy to be transmitted at the same frequency for a short period of time – just long enough for other power sources to react to the power deficit and pick up the slack, ensuring that the grid remains stable.
Lunar panels
Most renewable energy sources are at the mercy of nature. If the wind doesn’t blow, a wind turbine won’t turn. And following a period of low rainfall, less water passes through a hydroelectric power plant. But, in certain cases, a solar panel can keep producing electricity even after night falls.
How? The answer is simple: Thanks to the moon.
Moonlight is just reflected sunlight. As a result, a solar panel can continue to generate electricity when the moon is shining. However, there is a caveat. Even with a full moon and no cloud cover, a solar panel will still only produce approximately 0.3 % of the energy it would in direct sunlight. As this amount is so negligible, most solar power systems will not even convert it to usable electricity. But maybe one day, as solar panel technology develops, we could be powering our homes by moonlight.
Most renewable energy sources are at the mercy of nature. If the wind doesn’t blow, a wind turbine won’t turn. And following a period of low rainfall, less water passes through a hydroelectric power plant. But, in certain cases, a solar panel can keep producing electricity even after night falls.
How? The answer is simple: Thanks to the moon.
Moonlight is just reflected sunlight. As a result, a solar panel can continue to generate electricity when the moon is shining. However, there is a caveat. Even with a full moon and no cloud cover, a solar panel will still only produce approximately 0.3 % of the energy it would in direct sunlight. As this amount is so negligible, most solar power systems will not even convert it to usable electricity. But maybe one day, as solar panel technology develops, we could be powering our homes by moonlight.