Questions for ‘Gravity ‘batteries’ might help a weighty renewable-energy problem’

a huge crane-like structure rises into the sky in the valley of a mountain range

In July 2020, the company Energy Vault built this huge “battery” in the Swiss Alps. It releases power — electricity — or stores it by slowly lowering or raising heavy blocks.

Energy Vault

To accompany ‘Gravity ‘batteries’ might help a weighty renewable-energy problem


Before Reading:

  1. List three sources of energy. For each source, identify one problem associated with it. What source or sources of power do you think will be most important in the future? Explain your answer.
  2. In a phone, what part stores energy for later use? Why must this device be recharged? From where might the power for this recharge originate?

During Reading:

  1. The beginning of the story describes a deep pit in the eastern Czech Republic. What was this pit used for up until 2021? What does Gravitricity hope to use it for?
  2. Describe the objects that Gravitricity plans to suspend from cables over this pit. How will this system generate electricity? 
  3. What does it mean for a gravity storage system to “run in reverse”? Why is it important that this machine be capable of running in reverse? What problem will occur if the machine cannot run in reverse?
  4. What defines an object’s potential energy? What defines an object’s kinetic energy?
  5. Identify one limitation of using solar panels for energy. Identify one limitation of wind power.
  6. Briefly describe a pumped-hydropower system. What part of the system represents the potential energy? What part of the system represents the kinetic energy?
  7. What percentage of energy storage worldwide does hydropower provide?
  8. In what type of terrain does hydropower energy storage work best? 
  9. What is gravity? How does gravity explain why people stay stuck on the planet?
  10. If it works as planned, how many homes would Gravitricity’s Czech Republic machine be able to power for 30 minutes? Based on this time limitation, in what type of situations might gravity-based energy systems be most useful?

After Reading:

  1. Imagine a near-future world in which humans build a colony on Mars. How important would energy storage be for such a colony? Now consider the fact that Mars has lower gravity than Earth. For example, a rock weighing 100 pounds (45 kilograms) on Earth would weigh only 38 pounds (17 kilograms) on Mars. Based on that, how do you expect the performance of a gravity-based energy-storage system on Mars to differ from an identical system on Earth?
  2. Regarding energy storage, what does Robert Piconi mean when he says there’s no “silver bullet”? What are two ways that engineers and scientists in this story have used unique landscapes or environmental features to store energy?