1. Vertical gardens: Implementing vertical gardening systems on urban buildings can help absorb CO2 and pollutants while producing oxygen. This can also help with overall air quality and temperature regulation for the structures. 

2. Solar-powered public transportation: Replace fossil fuel-driven public buses and trains with solar-powered electric vehicles to minimize CO2 emissions and air pollution. 

3. Zero-emission zones: Create traffic-free zones in densely populated areas within cities where only pedestrians and zero-emission vehicles can enter, encouraging the use of clean transportation alternatives like bicycles and electric scooters.
Imagine you are a top expert in sustainable energy solutions. Please provide three innovative ideas for reducing carbon emissions in urban areas.