**Suggested Citation:**"Appendix C Description of NREL Model." National Academies of Sciences, Engineering, and Medicine. 2017.

*Utilizing the Energy Resource Potential of DOE Lands*. Washington, DC: The National Academies Press. doi: 10.17226/24825.

# C

Description of NREL Model

## OVERVIEW

The National Renewable Energy Laboratory (NREL) examined a number of technologies for generation of renewable electricity for export off-site. The analysis used the NREL REopt (Renewable Energy Planning and Optimization) model to calculate a levelized cost of electricity (LCOE) for photovoltaic (PV), wind, biomass, landfill gas (LFG), and waste-to-energy (WTE). For concentrating solar power, the System Advisory Model (SAM) was employed, and for geothermal, no analysis of LCOE was undertaken. NREL in addition conducted a sensitivity analysis to show the effect on LCOE of varying key parameters (Table C-1).

REopt was developed at NREL and efficiently screens a large number of sites by leveraging automated geographic information system (GIS) resource data, technology cost curves, and technology performance equations. According to NREL, “REopt is an energy planning platform offering multiple technology integration and optimization capabilities to help clients meet their cost savings and energy performance goals.”^{1} As inputs, REOpt uses location of sites, land availability, and utility usage. Inputs to the cost calculation portion of the model are based on market data and NREL research. The model uses energy performance models to estimate generation. The model uses site-specific information on incentives, export rates, and interconnection and net-metering limits. Energy escalation rates are based on projections made by the Energy Information Administration. The load profile is taken from the output of energy models based on building stock and climate zone.^{2}

SAM, according to NREL, “makes performance predictions and cost of energy estimates for grid-connected power projects based on installation and operating costs and system design parameters that you specify as inputs to the model.”^{3} SAM makes estimates of energy performance and costs based on user-input values, including, for example, the project’s location, the type of equipment in the system, the cost of installing and operating the system, and financial and incentives assumptions.

## INPUTS AND ASSUMPTIONS

The inputs to and assumptions on each technology, embedded within the respective models, are summarized in Table C-2. Interested readers who require further details are invited to consult Kandt et al. (2016).

___________________

^{1} National Renewable Energy Laboratory (NREL), 2014, *Renewable Energy Optimization (REOpt)*, NREL/FS-7A40-62320, Golden, Colo., June.

^{2} Adapted from NREL, 2014, *Renewable Energy Optimization (REOpt)*, NREL/FS-7A40-62320, Golden, Colo., June.

^{3} NREL, Welcome to SAM,” https://sam.nrel.gov/, accessed September 10, 2016.

**Suggested Citation:**"Appendix C Description of NREL Model." National Academies of Sciences, Engineering, and Medicine. 2017.

*Utilizing the Energy Resource Potential of DOE Lands*. Washington, DC: The National Academies Press. doi: 10.17226/24825.

TABLE C-1 Sensitivity Analysis on Renewable Energy

Input Varied | Lower LCOE | Central Scenario | Higher LCOE |
---|---|---|---|

1. Discount rate | 8% | 10% | 12% |

2. Technology costs | âˆ’20% | Varies, see Appendix C | +20% |

3. Energy output | +20% | Varies, see Appendix C | âˆ’20% |

4. Other | |||

Photovoltaics: ITC, SREC | 30% ITC | 10% ITC | No ITC |

Wind: PTC | 2014 PTC | No PTC | No PTC |

Biomass: Feedstock cost | âˆ’20% | Varies, see Appendix C | +20% |

Waste to energy: Tipping fee | âˆ’20% | Varies, see Appendix C | +20% |

Landfill gas: Fuel cost | âˆ’20% | Varies, see Appendix C | +20% |

NOTE: ITC, investment tax credit; LCOE, levelized cost of electricity; PTC, production tax credit; SREC, solar renewable energy credit.

## REFERENCE

Kandt, A., E. Elgqvist, D. Gagne, M. Hillesheim, and A. Walker, J. King, J. Boak, J. Washington, and C. Sharp. 2016. *Large-Scale Power Production Potential on U.S. Department of Energy Lands.* Technical Report NREL/TP-7A40-64355. Golden, Colo.: National Renewable Energy Laboratory. June.

**Suggested Citation:**"Appendix C Description of NREL Model." National Academies of Sciences, Engineering, and Medicine. 2017.

*Utilizing the Energy Resource Potential of DOE Lands*. Washington, DC: The National Academies Press. doi: 10.17226/24825.

TABLE C-2 Summary Description of Technologies as Used in NREL’s Analysis of Renewable Electricity

Technology | Configurations | Assumptions | Costs | ||
---|---|---|---|---|---|

Solar photovoltaic | Fixed axis | Overall system losses 14%; inverter efficiency 96%; annual performance degradation of 0.5% per year | Marginal installation cost: | 0-200 kW: $2.54/Wdc | |

>200 kW, <5 MW: $2.01/Wdc | |||||

>5 MW: $1.79/Wdc | |||||

O&M cost: | $0.020/W-yr | ||||

Single-axis tracking | Overall system losses 14%; inverter efficiency 96%; annual performance degradation of 0.5% per year | Marginal installation cost: | 0-200 kW: $2.69/Wdc | ||

>200 kW but <5 MW: $2.18/Wdc | |||||

>5 MW: $1.95/Wdc | |||||

O&M cost: | $0.023/W-year | ||||

Wind power | 30 acres of land needed per MW | Marginal installation cost: | 0-50 kW: $2.42 /Wdc | ||

15% loss assumed for wake effects, electrical losses and availability. | >50 kW but <850 MW: $2.38/Wdc | ||||

>850 kW: $1.75/Wdc | |||||

See Table C-3 for further assumptions. | O&M cost: | $0.035/W-year | |||

Biomass (all) |
Heat and/or electricity (see next row) |
Fuel cost: | On site: $0/ton | ||

25 mi. radius: $20.50/ton | |||||

25-50 mi. radius: $32.50/ton | |||||

Biomass (electric) |
Fully condensing turbine that generates electricity only |
Electrical efficiency | 23% | Marginal installation cost: | 0-713 kW: $26.78/W |

Availability | 85% | >713 kW but <6.67 MW: $8.04 | |||

Assumed efficiency of existing heating system |
80% | >6.67 MW: $1.83/W | |||

0-713 kW: $2.47/W-yr | |||||

Min. turndown ratio | 40% | >713 kW, <6.67 MW: $0.82/W-yr | |||

Fuel heat content | 9.2 mmBtu/ton | O&M cost: | >6.67 MW: $0.15/W-yr | ||

Landfill gas |
Internal combustion engine that generates electricity only |
Electrical efficiency | 33% | Gas cost: | $1/mmBtu |

Availability | 85% | Piping cost: | $346 200 | ||

Assumed efficiency of existin heatin s stem | 80% | Marginal installation cost: | 0-110 kW: $5.65/W | ||

Min turndown ratio | 30% | >110 kW but <3 MW: $2.56 | |||

Fuel heat content | 10.6 mmBtu/ton | >3 MW: $2.41/W | |||

Max. distance to landfill | 15 miles | O&M cost: | $0.25/W-yr |

**Suggested Citation:**"Appendix C Description of NREL Model." National Academies of Sciences, Engineering, and Medicine. 2017.

*Utilizing the Energy Resource Potential of DOE Lands*. Washington, DC: The National Academies Press. doi: 10.17226/24825.

Technology | Configurations | Assumptions | Costs | ||
---|---|---|---|---|---|

Waste-to-energy |
Fully condensing turbine that generates electricity only |
Electrical efficiency | 21% | Marginal installation cost: | 0-2520 kW: $15.60/W |

Availability | 85% | >2520 kW but <21 MW: $5.84 | |||

Assumed efficiency of existing heating system |
80% | >6.67 MW: $3.69/W | |||

Min. turndown ratio | 40% | O&M cost: | 0-2520 kW: $2.44/W-yr | ||

Fuel heat content | 10.4 mmBtu/ton | >2520 kW but <21 MW: $0.36/W-yr >6.67 MW: $0.14/W-yr |
|||

Concentrating solar power tower | Molten salt, BrightSource Heliostat LH-2.2; 539,654 m^{2} total reflective area. |
50 MW net (55-MW power plant with 9% parasitic losses) |
Installation: O&M: $0.065/W-yr |
$6.30/Watt for system size 50 MW | |

96% availability | Variable O&M: | $0.004/kWh | |||

6 hours of thermal energy storage | |||||

15 acres/MW |

NOTES: mmBtu = million British thermal units; kW = kilowatt; kWh = kilowatt-hour; MW = megawatt; O&M = operation and maintenance; W-year = Watt-year; Wdc = Watts direct current. SOURCE: Kandt et al. (2016).

TABLE C-3 Representative Turbines Used in NREL’s Analysis of Wind Power

Size | Small | Medium |
Large |
||
---|---|---|---|---|---|

Nameplate | 10 kW | 100 kW | 3,000 kW | 2,000 kW | 1,800 kW |

IEC class (average wind velocity) | N/A | N/A | Class 1 | Class 2 | Class 3 |

(≥9 m/s) | (7.5 m/s ≤ average wind speed <9 m/s) | (<7.5 m/s) | |||

Power control method | Stall | Stall | Pitch | Pitch | Pitch |

Nacelle height assumed | 30 m | 50 m | 80 m | 80 m | 80 m |