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This is a nice succinct intro to EROI. I've been thinking more about Hawai'i ever since Dr. Hall took his trip out there.

As you are well aware (but perhaps for the sake of others I'll recap) Hawai’i has no domestic sources of fossil fuels and thus 94% of the energy consumed on the island must be imported. To pay for these imports, island residents generate revenue through agricultural, industrial, and commercial production. In effect, Hawaiians collectively trade agricultural products, (e.g. coffee), light manufacturing (e.g. food processing, clothing) and services, (e.g. access to beaches, tourism and financial services) for imported energy, mainly oil. All of these means of economic production have an energy cost. From this information one can calculate an EROI for imported fuels (EROI-imp) for Hawai’i by measuring the energy imported / amount of energy consumed in the economy to obtain that energy. [Hall, Cleveland, and Kauffmann (1986) and Palcher et al. (2008) undertook similar calculations previously for the U.S. as a whole.]

Method for calculating the EROI for imported fuels:
EROI-imp is a function of the price of fuel and the energy intensity of the economy.
If a state or nation that is mainly dependent on service industries for economic production requires on average 5 MJ on average to generate a dollar’s worth of production, the energy intensity is 5 MJ/$. A barrel of oil contains 6,119 MJ of energy. At $50/barrel, the energy “intensity” of a barrel of oil is 122 MJ/$. Therefore, the EROI for imported oil is calculated as:

EROI= (Energy IN)/(Energy OUT)

EROI(imported oil)=(Energy intensity of oil)/(Energy intensity of the economy)

EROI (imported oil) =(122 MJ/$)/(5 MJ/$)=24:1

This means for every MJ of energy consumed in the service industries, enough money can be generated to purchase 24 MJ of imported oil. Or conversely, 1 out of 24 available units of energy must be consumed to secure continued energy imports. Only the remaining 23 units are surplus energy available “net” to society. More energy intensive economies (with high proportions of agriculture or heavy industry) would have a lower EROI for imported fuels. Likewise, higher oil prices would also serve to lower this ratio.

Therefore it may be more relevant and important to compare alternative energy projects (such as the geothermal electric plants you mention above) to the EROI for imported fuels in Hawai'i (and the projected changes to that ratio over time) than to the EROI for oil production in the US or world as a whole.


I've been developing a research proposal to examine of the current state of Hawaiian energy consumption and to analyze alternative energy recommendations using this metric (and assessment methods developed in the field of industrial ecology). The objectives of the study are to answer the following research questions: (1) What is the current EROI for imported fuels in Hawai’i and how has it changed over time? (2) How will proposed changes in fuel mix and a shift to domestically produced renewable fuels affect Hawaii’s overall EROI (domestic + imported)? (3) Alternatively, how might increases in the price of oil or changes in tourism spending affect the EROI of imported oil? (4) How will the proposed changes to the Hawaiian energy mix affect its material stocks and flows?

If these ideas interest you and you'd like to hear more about it, or you know of any local researchers who might be interested in pursuing such an analysis with me, please contact me via email or through Dr. Hall.

Stephen Balogh

p.s. thanks for the plug for our paper

Aloha Stephen
You hit the nail on the head! We absolutely need answers to the questions you pose. Mahalo for thinking of us! I'll get back to you soon.

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