A carbon revolution is underfoot to combat climate change and create a sustainable bioeconomy that integrates food, energy, and water needs for Hawaii. Hawaii is the most fossil fuel dependent state in the United States, with 90% of its energy from petroleum in 2014 and at a cost of $2.76 billion annually (The U.S. Energy Information Administration). To help alleviate this fossil-based energy dependency, the Hawaii Clean Energy Initiative (HCEI) was established in 2008 in conjunction with the U.S. Department of Energy with an aggressive target of achieving 100% renewable electric energy by 2045. Currently the project is exceeding interim targets due to rapid implementation of renewable electricity. However, progress on energy for transportation, which accounts for 66% of petroleum usage, is slower.
The environmental outlook of biofuels improved in recent years with awareness and efforts to maximize the net carbon balance of biofuel production, which includes factors for conversion efficiency, non-renewable emissions incurred within the system, and direct and indirect costs of land use change. Soil carbon loss as a result of land use change during cultivation of biofuel feedstocks negatively impacts the net global warming mitigation potential of a renewable fuel production systems, but losses can be minimized or C accrued with sustainable management practices. We explore the carbon tradeoffs of production associated with potential bioenergy feedstocks, with a recent focus on soil carbon sequestration with the cultivation of perennial grasses in degraded or fallow soil.