The State of Hawai‘i and the U.S. are developing greenhouse gas (GHG) emissions reduction regulations in parallel. The State requires that economy-wide GHG emissions be reduced to 1990 levels by the year 2020 and the U.S. Environmental Protection Agency is developing new source performance standards (NSPS) for new electricity generation units. The State Department of Health has proposed rules that would reduce existing large emitting electricity generating units by 16% from 2010 levels. The NSPS proposes GHG concentration limits for new electricity units.
We use a comprehensive model of Hawai‘i’s electricity sector to study the potential cost and GHG impacts of State and Federal GHG regulations. Given uncertainty about the final form and implementation of these regulations, we adopt a series of scenarios that bracket the range of possible outcomes. First we consider the State’s GHG cap (for existing units) and NSPS (for new units) being implemented at the facility level. Next, we consider the implications of allowing for partnering to meet the State GHG cap and the NSPS at a system-wide level. We also consider the case where the State GHG cap is extended to apply to both existing and new units. The current proposed State GHG rules exclude biogenic sources of emissions. We address the impacts of this decision through sensitivity analysis and explore the impact of GHG policy on new coal-fired units.
We find that regulating GHGs at the facility level leads to greater reductions in GHG emissions but at higher cost. Over the 30-year period that we study, when biogenic sources of emissions are ignored, facility level implementation of policy will add $3 billion to the cost of electricity generation at an average cost of $180/ton of GHG abatement. If biogenic sources of emissions are included within the accounting framework, abatement costs rise to $340/ton.
Overall, we find that the high cost of Hawai‘i’s current electricity generation provides a strong incentive to move towards less costly alternatives – in this consideration, primarily wind and rooftop PV. This leads to a reduction in GHG emissions. However, this finding would not hold if fuel prices were substantively lower than current levels, either from falling prices or fuel-switching to lower cost products. Regardless, the qualitative implications about the optimal structure of GHG policy are robust to changing assumptions about fuel prices. Implementing GHG policy at the facility level leads to relatively higher levels of GHG emissions reductions, though at substantially higher cost. If a greater level of GHG emissions reduction is desired, the least cost policy is to lower the level of the GHG cap while still allowing for the greatest flexibility in achieving targets.
