Electricity

Electricity provided a way to pipe energy around. They are one key factor that allowed the modern city to thrive.
The real cost of electricity (for cities) comes in generating it from other sources of electricity (coal, hydropower, etc…)
- In principle, all forms of electricity generation rely on Induction — move a wire through a magnet.
We need transformers to control the amount of electricity each area in the city receives. Transformers manage the supply of electricity.
- The transformers form a part of the Electricity Grid.
  - At the local level, transformers are connected via substations via distribution lines
  - At a larger level, distribution lines are connected to energy sources via transmission lines, usually characterized with thicker electric cables.

Heat

The alternative to electricity is natural gas which are pumped to buildings to be used in heating systems.
- An alternative is district energy which relies on pumping water from heavily insulated pipes. The water is independent from the city’s water supply and can use wasted heat energy from generators.

Wind turbines are tall because they capture the highest speed wind possible.
The amount of energy captured from the wind is proportional to the speed of the wind that turns the turbine.
Wind turbines have aerofoil-shaped blades to cut through the wind easily, allowing it to spin more easily and to spin the loops of wire in the generator.
Longer blades = more wind that can be harvested.
Something to consider is the composition of the blade since they can bend after repeated use.
Another thing is the weather — they are dependent on the presence of wind.

Getting energy from the sun via solar panels which consist of photovoltaic cells.
We tend to use a sandwich of silicon
- A bottom layer that is positive (p-type)
- A filling that is negative (n-type)
- A layer of anti-reflective glass to prevent light from being reflected (and hence not harvested).
Solar panels work effectively by a chain of electrons — photons excite the filling which pushes an electron to the bottom layer and so on.
We need to consider the angle the solar panel faces the sun.

Cities are the dominant force behind economic growth. Electricity improves productivity.
We are looking more towards renewable energy.
More population means more demand for electricity.
Better grid design.
Use of a smart grid system to monitor varying energy supply and demand.
Distributed generation — households having storage systems or generators on site.
Use of mini-grids.
Combined Heat, Power, and Cooling System — using hot water from the generator for the building.
Electric vehicles and how to account for them.
Use of trees and greenery to make cities cooler and mitigate the urban heat island effect.
Improving existing renewable energy methods.
Energy storage methods
Better and longer-lasting batteries.