Greenhouse Gas Emissions

By January 2020, reduce annual statewide greenhouse gas emissions to 1990 levels.

Understanding the Goal and Its Data

In June 2014, the Department of Health (DOH) amended the Hawaiʻi Administrative Rules to regulate greenhouse gases (GHG). The rules were developed to implement GHG reduction goals of Hawaiʻi Act 234 (session laws of 2007) to ensure the state returns to 1990 GHG emission levels (14.95 million metric tons per year) by 2020. To track progress, new statewide GHG emission inventories are being compiled for 2017 emissions year; statewide GHG projections are also being developed for 2020 and 2025.
As of December 2019, full emissions inventories for the years 1990, 2007, 2010, 2015 & 2016 have been completed by ICF, the University of Hawaiʻi faculty and the Department of Health, accounting for contributions from everything from motorcycles to solid waste treatment facilities. These emissions are presented as million metric tons of "carbon dioxide equivalent," a standard developed by the IPCC that allows for comparison between gases in terms of their ability to trap heat, and not simply their concentration. Greenhouse gas emission regulations help support existing energy efficiency and renewable energy programs already in place to reduce GHGs. If data from tracking GHGs indicates the statewide emissions limit is met prior to 2020, a GHG emissions cap will not be required. As of 2016, the state was on track to meet the goal. 
The power sector represents a majority of the statewide greenhouse gas emissions. In recalculating 1990 baseline emissions and completing inventories for 2007, 2010, 2015 and 2016 with updated methodologies and data, the December 2019 ICF/UH/DOH inventory report found that energy accounted for 88% of the emissions increase from 1990 to 2007 and 99% of reductions between 2007 and 2016.
Note: One metric ton of CO2e is equivalent to the greenhouse gas emissions generated from driving 2,434 miles in an average car per year.

Complete GHG Emissions by the Energy Sector

Figure 1. The above chart shows a complete inventory of emissions from the energy sectors in million metric tons (MMT) of CO2 equivalent: stationary combustion, transportation (excluding domestic aviation per the statewide goal in Act 234), oil and natural gas systems, and the incineration of waste.  

Figures 2 & 3: The above pie charts show the contributions of various sources within the energy sector (left) and from various economic sectors that participate in stationary combustion (right). Stationary combustion remains the biggest contributor, with 88% of emissions within this category coming from electric power plants and petroleum refineries. 

Figure. The pie chart above (Figure 4, left) shows the contribution of each transportation sector; as of 2015, ground transportation is the heaviest emitter. While the 2020 goal set out in Act 234 excludes domestic aviation, greenhouse gas emissions from air travel within and originating in Hawaiʻi have seen the greatest decrease since 1990 of all transportation sectors.

Source: Hawaii Greenhouse Gas Emissions Report for 2016, December 2019. 

Power Plant Emissions

Figure 6: The above chart shows self-reported CO2e emissions from 15 large sources in the power sector (power plants) from 2010-2017 in comparison to the 1990 power sector baseline GHG emissions level (line in red).

Source: EPA 2017 Greenhouse Gas Emissions for Large Facilities

Note: The 1990 baseline shows emissions from all sources evaluated in the power sector, including large and small emitters. The data from 2010-2017 only shows emission totals from large stationary sources in the power sector emitting 25,000 metric tons of GHG or more per year.

Learn More and Make a Difference

What You Can Do to Reduce Your Carbon Footprint

Carbon footprint is measured as the total greenhouse gas emissions produced by an organization or individual. To calculate your carbon footprint, check out the Environmental Protection Agency (EPA) Carbon Emissions Calculator.
The following actions can reduce your carbon footprint:
  • Use alternative means of transportation, such as carpooling, biking and riding the bus. Leaving your car at home just two days a week will reduce greenhouse gas emissions by an average of 1,600 pounds per year.
  • Under-inflated tires reduce your fuel economy and lead to increased emissions of greenhouse gases and air pollutants.
  • Plant trees and vegetation to serve as carbon sinks (which take CO2 out of the atmosphere).
  • Reduce electricity usage by turning off lights and appliances and unplugging them when not in use. Even equipment that is off, but still plugged in, draws electricity.

More Information

The Clean Air Branch of the State of Hawaiʻi’s Department of Health has established a Greenhouse Gas Program to combat the threat of climate change and sea level rise. Learn more about the program and Hawaiʻi’s GHG rules here.
The EPA provides publicly available data to track Hawaiʻi's large stationary source GHG emissions. To check out specific facility information, use its Greenhouse Gases Tool.
SDG 7 - Affordable and Clean Energy
Ensure access to affordable, reliable, sustainable and modern energy for all
SDG 10 - Reduced Inequalities
Reduce inequality within and among countries
SDG 12 - Responsible Consumption and Production
Ensure sustainable consumption and production patterns
SDG 13 - Climate Action
Take urgent action to combat climate change and its impacts
SDG 17 - Partnerships for the Goals
Revitalize the global partnership for sustainable development