Power systems modelling with HOMER US-Denmark Renewable Energy Workshop 2014

Computer model for the design and evaluation (economic and technical feasibility) of both off-grid and on-grid power system configurations with a

number of technology options

What is it?

Sensitivity Analysis Optimization process can be performed defining ranges for sensitivity

variables to determine the potential impact of uncertain factors over time (costs, resources).

How does it work?

Optimization Sorted list of configurations by LCOE

Simulation Energy balance calculations for each hour

and configuration

• Are configurations feasible?

• What is the cost of installing and operating the system over project

lifetime?

Conventional and renewable energy technologies

• Daily profiles with seasonal variation

• Deferrable (water pumping, refrigeration)

• Thermal (space heating, crop drying)

• Efficiency measures

LOADS

• Solar PV • Wind turbine • Mini Hydro • Biomass power • Generators: diesel, gasoline,

biogas, alternative fuels, cofired. • Electric grid • Microturbine • Fuel Cell

POWER SOURCES

• Battery bank • Hydrogen • flywheels

STORAGE

Some key concepts

• Capacity factor (intermittent resources) • Levelized cost of electricity

• Demand profile

Concepts: Capacity Factor Indicates how often the energy is produced (intermittent resources)

CF = Energy Produced kWh /(Rated Powerkw x 8760hrs/yr )

Wind, Onshore 0.38 Wind, Offshore 0.39 Solar, Photovoltaic 0.16 Concentrating Solar Power 0.43 Geothermal, Hydrothermal 0.95 Hydropower 0.50 Fuel Cell 0.95 Natural Gas Combined Cycle 0.87 Natural Gas Combustion Turbine 0.30 Coal, Pulverized Coal 0.85 Coal, Integrated Gasification Combined Cycle 0.85 Nuclear 0.90

Typical capacity factor values

Source: NREL (http://www.nrel.gov/analysis/tech_cost_data.html)

Concepts: Levelized cost

The minimum price ($/kWh) at which energy must be sold for an energy project to break even over the life of the project. It assesses the cost of the energy-generating system including all the costs over its lifetime: initial investment, operations and maintenance, cost of fuel, cost of capital.

Source: IEA and IER http://instituteforenergyresearch.org/topics/policy/electricity-generation-cost/

Step 1: Problem formulation

• Is it cost-effective to add a wind turbine to the diesel generator in my system?

• How much will the cost of electricity need to increase to make photovoltaics cost effective?

• Will my design meet a growing electric demand? • Is it cost-effective to install a microturbine to produce electricity and

heat for my grid-connected facility?

Example: How do changes in average wind speed and fuel price affect the feasibility of adding wind turbines to a diesel-only system design?

Step 2: Create a new file and build the power system

Step 3: Define the load

Step 4: Equipment details

Step 4a: Generator

Step 4a: Generator Cost

Note: Unless otherwise noted, HOMER assumes linear cost curves. Non-linear curves (to account for economies of scale) can be defined by adding rows to the costs table.

Tip: Hold the pointer over an element for a quick description.

Step 4a: Generator Fuel

Step 4b: Wind Turbine

Step 4c: Battery

Step 5: Resources

Step 5: Resources

Step 6: Economics

Step 7: Correct errors

Step 8: Optimization results

Step 8: Optimization results

Displays all feasible system configurations

Displays only the most cost effective configuration of each system design.

Step 9: Sensitivity analysis results

Solar PV panels

Solar resource

2. Biomass supply is constrained for all or part of the year Choose "Biogas" from the list of fuels for a particular generator

(biomass resource button will appear in the schematic)

Use Biomass Resource Inputs window to specify fuel characteristics

Feedstock availability & price, biogas properties

How to model Biomass generator?

1. Biomass feedstock is abundant throughout the year Define your own fuel on the Generator Inputs window

heating value, density, cost, zero carbon content .

Careful! specify generator's fuel curve inputs properly (Fuel Curve Calculator)

Biomass Generator

1 2

Defining biomass fuel

1

Defining biomass fuel

Defining biomass fuel

2

Check generator efficiency curve!

Option 2. Biogas resource

Questions?

Month Wind Speed (m/s)

Jan 6.6 Feb 4.95 Mar 5.17 Apr 3.85 May 9.13 Jun 9.46 Jul 9.46 Aug 9.57 Sep 8.36 Oct 9.02 Nov 8.47 Dec 7.37

Wind Speed Monthly Averages

Model MADE AE59

Rated Power (kW) 800

Output type AC

Hub Height (m) 50

Wind Turbine specifications

Wind speed (m/s)

Power Output (kW)

0 0 1 0 2 0 3 0 4 21 5 63 6 122 7 209 8 323 9 461

10 605 11 746 12 800 14 800 16 800 18 800 20 800 22 800 25 800 25 0

ASSIGNMENT INPUTS