Demand response is a way to balance the electric grid by changing when people and machines use power. It matters because solar panels and wind turbines do not always produce the same amount of electricity at the same time people want to use it. Instead of only building more power plants, the grid can ask flexible devices to run earlier, later, or at lower power.
This helps keep electricity reliable while using more renewable energy.
Key Facts
- Power demand is the rate at which electricity is used, measured in watts: P = E/t.
- Electrical energy used by a device is E = Pt, where E is energy, P is power, and t is time.
- Demand response shifts flexible loads away from peak demand times and toward times with abundant renewable generation.
- Peak load is the maximum total power demanded from the grid during a time period.
- Reducing peak demand can lower stress on transmission lines, transformers, and backup power plants.
- Smart devices can respond to grid signals such as price, frequency, or renewable energy availability.
Vocabulary
- Demand response
- Demand response is the adjustment of electricity use in response to grid needs, prices, or renewable energy supply.
- Load
- A load is any device or system that uses electrical power, such as an air conditioner, charger, pump, or factory motor.
- Peak demand
- Peak demand is the highest amount of electrical power used by customers during a certain period.
- Smart grid
- A smart grid is an electric grid that uses sensors, communication, and control systems to manage electricity more efficiently.
- Flexible load
- A flexible load is an electrical use that can be delayed, reduced, or scheduled without greatly affecting the user.
Common Mistakes to Avoid
- Confusing demand response with using less energy overall is wrong because demand response often shifts energy use to a better time instead of eliminating it.
- Assuming every device is flexible is wrong because some loads, such as medical equipment or lighting needed for safety, must operate immediately.
- Ignoring units in E = Pt is wrong because power in kilowatts multiplied by time in hours gives energy in kilowatt-hours, not watts.
- Thinking demand response only helps during shortages is wrong because it can also absorb extra solar or wind power when renewable generation is high.
Practice Questions
- 1 A water heater uses 4.5 kW and runs for 2 hours. How much electrical energy does it use in kWh?
- 2 A factory delays a 30 kW motor from 5:00 p.m. to 11:00 p.m. and runs it for 3 hours. How much demand is removed from the 5:00 p.m. peak, and how much energy is still used?
- 3 Explain why charging electric vehicles at midday can help a grid with many solar panels, even if the total daily energy used by the vehicles stays the same.