Understanding Sources and Uses of Energy in Urban Areas
Setting priorities for climate action at the local level requires understanding where the biggest sources of emissions are and where you can get the biggest bang for your buck. As a foundation, you need to understand the sources and uses of energy in the local economy to set priorities. This post provides an overview of the tools available to do this analysis and some examples drawn from Northwest communities.
What is an Energy Map?
Energy Maps are a snapshot of energy uses, sources, and greenhouse gas emissions within a jurisdictional geographic boundary at a point of time against a defined base year. Lawrence Livermore National Laboratory (LLNL) produces energy map graphics for the United States and each of the states (see Washington and Oregon's energy flowcharts by using the dropdowns).
Energy Maps are a tool that helps people understand a community’s energy system in one picture and can be used as a starting point for discussion. They represent order-of-magnitude estimates based on best available local data and research assumptions and are intended to depict the broad scale of action needed to reduce carbon emissions.
Data Sources for Energy Mapping
To create energy maps, we use these data as inputs
- Vehicle miles traveled from local metropolitan planning organizations
- Electricity and gas consumption from the local utility
- Population growth to estimate increase in emissions: cities or counties provide this factor
To understand the importance of a clean electricity grid, we will look at two graphics that display the fossil fuel content of the Puget Sound electricity providers, Puget Sound Energy and Seattle City Light.
Puget Sound Energy Mix
As you can see, 59% of Puget Sound Energy's electricity’s fuel mix is fossil fuel-based, 37% coal, and 22% natural gas.
Seattle City Light Electricity Fuel Mix
Here you see that Seattle City Light’s fuel mix is only 2% fossil-fuel based (1% coal and 1% natural gas). The differences between the carbon intensity of the two utilities' fuel mixes will quickly become apparent in the energy maps that follow.
How to Read an Energy Map
Let’s start first by looking at how to read an Energy Map with this 2012 map of the King County-Cities Climate Collaboration:
You read the map from left to right, as the sources of energy on the left flow through to their various uses on the right—residential, commercial, or transportation. You can see that the gray boxes on the far left and right represent total greenhouse gas emissions countywide, in millions of metric tons.
You see that the electricity generation is fueled by hydropower in blue; other renewable in green; as well as the coal in red and some of the natural gas in yellow. Natural gas is also used to heat residential and commercial buildings as indicated by the yellow lines that flow to those gray boxes. The brown petroleum box fuels transportation.
This map accounts only for emissions related to electricity generation and direct natural gas consumption for the building sector, and combustion in on-road transportation for passenger vehicles and light trucks. Other important emissions sources not included here are air travel, heavy duty trucks, and consumption.
King County-Cities Climate Collaboration (K4C)
The King County-Cities Climate Collaboration (K4C) is a voluntary partnership of 13 cities and the county that represents 1.5 million people (75% of the county’s population) and emits nearly 26% of Washington State’s greenhouse gas emissions. The K4C Energy map shows the following:
- Coal is approximately 3 million metric tons of the overall 12.9 million metric tons of greenhouse gas emissions, or one-quarter of the total carbon emissions.
- Next you see that the natural gas also is used directly in residential and commercial buildings and represents 4 million metric tons, or one-third of the overall greenhouse gas emissions.
- Finally, you see the petroleum used to power various forms of transportation, which at approximately 5 million metric tons, represents 42% of the overall GHGs.
- In terms of the carbon emissions, you note that the hydro and the renewables are not included in the carbon emissions, which are created by the coal, natural gas, and petroleum.
On the right side of the flow chart, you see the breakdown of carbon emissions by residential and commercial buildings and transportation; 25% of the emissions are in residential; 33% are in commercial; and 42% are in transportation.
This data include unincorporated King County. For reference, cities account for approximately 90% of King County’s total electricity and natural gas use and the electricity mix represents both Seattle City Light and Puget Sound Energy’s resources.
Olympia Energy Map 2014
Now let’s look at Olympia, whose electricity provider is Puget Sound Energy. You see how the much more fossil fuel impacts Olympia’s carbon footprint.
Residential is 22%; commercial is 32%; industrial is 3%, for a combined total of 56% of non-transport emissions. Transportation is 44% of the overall carbon emissions.
Shoreline Energy Map 2012
Seattle’ City Light's very clean energy is on full display with Shoreline’s Energy Map. (The King County cities of Burien, Tukwila, SeaTac, Shoreline, Lake Forest Park, and Renton are all powered by Seattle City Light.)
Shoreline with a population of 55,333, has a carbon footprint that is nearly three times lower than Olympia’s, which has a population of 51,202.
With so much clean electricity powering buildings and industry, Shoreline’s focus for carbon reduction strategies must be on transportation (55% of the community’s carbon emissions come from transportation and 46% are in buildings). This will be even more apparent in Part Three of this four-part series.
For further information regarding this subject, see the Clean Energy Transition Institute's presentations on City-Led Clean Energy Innovation, Urban Clean Energy Efforts, and City-Led Climate Action. Also see the City Climate Solutions References list.
Part Two of a four-part series examining the role local jurisdictions can play in reducing carbon emissions: