Kō: Hawaiʻi’s Legacy; Hawaiʻi’s Future
The histories of kō (sugarcane) and Hawaiʻi are inseparable. Introduced by Polynesian wayfinders between 700 and 1,700 years ago as a canoe crop, sugarcane was grown by Native Hawaiians for food and medicine. Post-contact it has—for better or worse—played a central role in Hawaiʻi’s agriculture, economy, labor importation, cultural development, environment, and political evolution. About two centuries later, Hawaiʻi’s sugarcane plantation industry ended in 2016 with the closure of the last sugar mill facility, Hawaiian Commercial & Sugar Company, on Maui.
Can we say that sugarcane’s impact on Hawaiʻi is finished?
Traditional Hawaiian sugarcane varieties.
The answer, surprisingly, is that sugarcane may be on the verge of a rebirth. This, however, will not be the plantation-style sugarcane experience of years past. Paths forward are based on entirely different approaches to agronomics (how we grow it), and how we use cane.
New agronomics will focus on environmentally friendly practices to get the most sugarcane yields (sucrose and plant organic material) with low inputs (fertilizer, water), minimum tillage after planting, long ratoons (new shoots), reduced costs, and maximum CO2 captured from the atmosphere and carbon storage in roots to increase soil organic matter and improve soil health. Marginal, poor-fertility soils that are underutilized and need replenishment will be targeted, to reverse prior degradation and avoid land use competition with food crops. Recent research in Brazil and Florida has demonstrated that well-managed sugarcane provides substantial sustainability and ecosystem improvements--including reduced greenhouse gas emissions and increased soil carbon storage --over low-input pasturelands of natively regenerated and poor quality tropical grasses typically used for forage.
Dr. Bruce Mathews, Dean of UH Hilo’s College of Agriculture, Forestry and Natural Resource Management (CAFNRM) has identified specific varieties that show promise for this new approach to sugarcane cultivation, and will initiate field trials in 2021 to test these conditions with support from the USDA PBARC facility in Hilo. He expects future partnerships with Lawrence Berkeley National Laboratory and cutting-edge companies to bring “SmartFarm” technologies developed for other crops (corn, rice) to sugarcane here in Hawaiʻi. These approaches will advance scientific understanding and demonstrate new ways to grow sugarcane economically and sustainably, providing direct benefit to farmers and laying the foundation for new “bioeconomy” applications that capture carbon from our biosphere, create a circular economy, and replace the further use of fossil fuels. One exciting project involves the conversion of sugarcane to a high-performance aviation fuel that would allow every trans-Pacific flight to fly more miles, passengers and freight per gallon of fuel with reduced emissions!
An example of a biofuel made from waste woody biomass.
Sugarcane matters for the bioeconomy because it produces the highest amount of biomass (harvested plant organic material, typically stalks and leaves) of any global crop, and traditional sugar extraction also produces the highest-volume co-product (bagasse). Bagasse has generally been burned for power but is a promising biomass source to make valuable bio-products (renewable fuels, chemicals, and materials made from biomass or other sources of recycled carbon). This makes sugarcane the leading biomass candidate for the bioeconomy. Since Hawaiʻi Island’s many climate zones and soil types have been shown to correlate agronomically with most of the world’s tropics, demonstrations of new ways to grow sugarcane here can be readily exported for global benefit.
Sugarcane sugars, plant material and bagasse can be used directly or with further treatment as input to fermentation systems that use biocatalysts (metabolically manipulated host organisms, such as yeast) to make specific target bio-products such as fuels, chemicals, and plastics. It’s a process akin to beer brewing, except that useful molecules other than ethanol are obtained.
The California company Amyris is already using Brazilian sugarcane as feedstock to ferment a fifteen-carbon molecule called farnesene. Originally developed and certified as an aviation fuel, its consistent and large volume supply opened new and sometimes unexpected markets. For example, a superior synthetic rubber based on farnesene is now the basis for Dunlop’s “best tire to date” in low-temperature conditions for durability and on-ice and snow-braking performance!
Additionally, when chemically coupling two farnesene molecules together, the thirty-carbon structure squalene is created. Squalene is used extensively in cosmetics and sunscreens for its preferred properties as an emollient and moisturizer. Squalene is currently sourced primarily from shark livers, with roughly 90% of shark-derived squalene used for cosmetics.
Squalene recently appeared in the news due to its use as an adjuvant (immune response-enhancing co-ingredient) in an estimated five COVID-19 vaccines under development. Shark Allies, a non-governmental organization dedicated to conserving sharks and rays, warned that sole use of these vaccines globally could lead to an additional 500,000 sharks being killed to harvest squalene. Although competition among the many COVID-19 vaccines under development indicates vaccines will likely have a much reduced impact on shark hunting, cosmetic use alone leads to an estimated kill of 2 – 3 million sharks per year. Sugarcane-based squalene is a critical non-lethal alternative that could help in protecting sharks.
As exciting as it is that sugarcane can provide better vaccines, smoother skin creams, safer tires, and fuel for cars and jets, it’s equally gratifying to see the current use of kō for local Hawaiʻi production and global consumption. Specialty rum producers across the State make delicious spirits from Hawaiʻi-grown sugarcane. On the Big Island, Kuleana Rum Works makes prized rum agricole out of fresh-pressed sugarcane juice from 40 heirloom Hawaiian sugarcane varieties grown on their Kohala farm! These heirloom varieties that serve as the basis for their unique rums were selected with the help and guidance of Dr. Noa Lincoln who compiled years of sugarcane research into a recently published book entitled Kō: An Ethnobotanical Guide to Hawaiian Sugarcane Varieties. Kuleana has expanded on its success with local and export sales, a Rum Shack restaurant, and agri-tourism tours—all creating growth opportunities here on Hawaiʻi Island.
During the pandemic, Kuleana Rum shifted their rum production to create hand sanitizers and was recently awarded a $500,000 PPE (personal protective equipment) supply-chain grant from the State of Hawaii to produce sanitizer from their kō supply. The company was able to greatly lower their cost of goods on the production of the main ingredient (ethanol) by using the kō grown locally at their farm, making it available to Hawaiʻi and foregoing the need to import from out of state. We at ʻImiloa are one of the many organizations that benefit from Kuleana Rum’s hand sanitizers - and we’ve been using them for our Hālau Lamakū program sanitization.
Kuleana Rum sanitizer at ʻImiloa’s Hālau Lamakū Enrichment Program.
Hawaiʻi sugarcane has a long legacy, current revival with specialty rums, and exciting future prospects for bioeconomy! Kō is definitely a driver of agricultural growth, new career opportunities for Hawaiʻi’s people, and climate change solutions with highly leveraged global impact, and we look forward to the research and potential that will stem from this Hawaiian rooted plant in 2021.