Energy and economic assessment of distributed renewable gas and electricity generation in a small disadvantaged urban community

Abstract

A methodology for assessing the efficiency and economic viability of renewable gas generation and energy conversion to compliment residential PV is proposed and demonstrated for the 10,000 resident example community of Oak View in Huntington Beach, California. Renewable fuel production processes included in this work are (1) processing of community-produced organic fraction of municipal solid waste in an anaerobic digester, and (2) using solar generation paired with water electrolysis. Six pathways – three ending in natural gas pipeline injection and three ending in solid oxide fuel cell electricity production – were evaluated for each PV capacity scenario. The renewable fuel production potential based only upon waste from the studied community was determined to be 2400 MMBtu per year of renewable natural gas (RNG) from anaerobic digestion, and up to 28,500 MMBtu of hydrogen from electrolysis using only excess solar PV electricity. With current costs the levelized cost of energy (LCOE) for renewable fuel production is $40–203/MMBtu, depending upon the energy pathway and scale. The LCOE for renewable electricity production is $0.37–1.28/kWh. A combination of LCFS and tipping fees as low as $20 per ton can yield renewable fuel at $2 per MMBtu. Likewise, a tipping fee of $32 can lead to the production of renewable electricity at $0.18 per kWh. Using future costs, the unsubsidized cost of electricity can drop as low as $0.15 per kWh, and renewable fuel can be produced at $18 per MMBtu. If Low Carbon Fuel Credits exist in 2050, a tipping fee of less than $9 per ton can yield renewable fuel at $2 per MMBtu. On an energy basis, over 80% of the community electrical demand can be met through a combination of local solar PV, anaerobic digestion, and fuel cell operation (80% zero net electricity). In this scenario, solar PV meets 52% of the community electrical load, while excess solar production produces hydrogen that is passed through a fuel cell to meet 26% of the electrical load. The remaining 3% is met using RNG produced through anaerobic digestion using only organic waste from the studied community. This analysis indicates that the production of renewable fuel in the urban environment is currently not economically feasible but will become competitive with conventional energy in the future.