This session is part of the Clean Energy Regulators Initiative Webinar Programme.
Theme 9 - Energy Access
Module 2: Rural Electrification Models and Costs
The economics of rural electrification has dramatically changed in the last few years. Fuel prices remain volatile and the technology has improved. In the past, the only economically viable options were grid extension and diesel generators. Now there is a wide range of renewable and hybrid options that are not only technically mature and reliable, but also cost-effective.
This webinar will use results from NREL’s HOMER® modeling software to illustrate the conditions under which different electrification models are most appropriate. In addition to diesel generators and grid extension, the webinar will discuss business models distributing individual systems, such as solar home systems and solar lanterns. The main focus will be on hybrid renewable mini-grids that can range from a few kWs to tens of MWs. It will compare the economics of solar and wind and the impact of different penetrations rates.
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Rural Electrification Models and Costs
1. Optimizing Clean Power Everywhere
1790 30th St, Suite 100, Boulder, Colorado 80301, USA
http://www.homerenergy.com ● +1-720-565-4046
Rural Electrification
Models and Costs
Dr. Peter Lilienthal
peter@homerenergy.com
3. What is best?
• Depends on the application
–Resources
–Loads
–Equipment prices
–Equipment performance
• A confused mind says “No!”
• HOMER fits the pieces together
http://www.homerenergy.com
4. Modeling Challenge
• Solar and wind are variable
– Chronology is important
– Needs integration with dispatchable resources
• Smaller projects need simpler tools
http://www.homerenergy.com
5. HOMER
• Industry standard for hybrid micro-grids
– Conventional resources
– Renewable resources
– Storage
– Load Management
http://www.homerenergy.com
6. HOMER
• NREL: 1992-2009
• Original developers now at HOMER Energy
• 122,000+ users in 193 countries
0
200
400
600
800
1,000
1,200
20102009200820072006200520042003200220012000
New users per month
http://www.homerenergy.com
7. HOMER Analysis Layers
• Simulation
– Accurate analysis of time varying
loads and resources require an hour-
by-hour analysis for entire year
• Optimization
– Find the least cost solution
• Sensitivity Analysis
– The data is never “good enough”.
– What if….?
Simulation
Optimization
Sensitivity Analysis
Energy Balance
http://www.homerenergy.com
8. HOMER bridges different worlds
Renewable Advocates
Utility Operators
HOMER
Model
Power
Engineers
Financiers
HOMER as a communication tool
http://www.homerenergy.com
9. Flexible Data Requirements
• Rough estimated inputs for general
analysis
– Annual averages for resources and loads
– Cost per kW or unit for equipment
• Detailed inputs for system design
– Measured hourly data
– Detailed cost curves
– Create your own wind turbine, battery, fuels
http://www.homerenergy.com
10. Answers from HOMER
• Optimal System Design
• Cost Breakdowns and Comparisons
• Resource Analysis
• Technology Development Targets
• Policy Analysis
• Operational Analysis
http://www.homerenergy.com
11. Policy Analysis
• Cost of emission constraints
0 5,000 10,000 15,000
0.0
0.2
0.4
0.6
0.8
1.0
1.2
LevelizedCostofEnergy($/kWh)
Levelized Cost of Energy vs. Max. CO2 Emissions
Max. CO2 Emissions (kg/yr)
http://www.homerenergy.com
12. Operational Analysis
• When is backup power needed?
Jul 10 Jul 11
-5
0
5
Power(kW)
AC Primary Load
PV Pow er
Diesel Pow er
Battery Pow er
http://www.homerenergy.com
13. Rural Electrification Models and Costs
• Individual Systems
– Solar Lanterns
– Solar Home Systems
– Renewable Power for Micro-enterprise
• Microgrids
– Part-time diesels
– Small 100% renewable systems
– Fully integrated hybrid systems
http://www.homerenergy.com
14. Paths to Full Electrification
http://www.homerenergy.com
Kerosene & Batteries
Individual solar
systems
Part-time diesels
Fully integrated
hybrids
15. Part-time Diesels
• Low capital cost
– Popular with funders
• High fuel costs
– Questionable sustainability
• Poor part-load efficiency
– Without batteries, only supply evening power
– Little economic development potential
• Little incentive for energy efficiency
http://www.homerenergy.com
16. Individual Solar Systems
• Simple, typically DC
• Have become inexpensive
• Can provide 24 hour power
• Without backup genset
– Only supply limited quantities
– Battery management is the challenge
• Temptation to over-discharge
• Difficult to equalize battery cells
http://www.homerenergy.com
17. Fully integrated Hybrids
• 24 hour AC power
– Often better than the central grid
• Batteries for off-peak loads
• Diesel for peak loads
• Solar to minimize diesel usage
• Basically a mini-utility
– Metering, tariff collection, admin. challenges
– Pre-pay meters
http://www.homerenergy.com
18. When is grid extension better?
http://www.homerenergy.com
19. Hybrid Design Tradeoff
More Diesel
More Storage
Solar Home
Systems
Multi-megawatt
scale systems
Small Systems Large Systems
High Penetration Low – Med. Penetration
http://www.homerenergy.com
20. Size Makes a Difference
• Battery based systems
– < 1 kW, no backup genset
– 1-100 kW, single genset, infrequently used
• Diesel based systems: > 100 kW
– Multiple gensets should be optimized
– Role of batteries evolving rapidly
• Stabilization
• Spinning reserve
• Diesel off during off-peak hours
http://www.homerenergy.com
21. For small systems, PV is cost-effective, almost everywhere.
http://www.homerenergy.com
PV is cost-effective
Not cost-effective
22. Community Systems with Optimized Diesel
http://www.homerenergy.com
PV is cost-effective
Not cost-effective
25. Different Definitions of Penetration
• Instantaneous
Penetration
– High winds in the middle
of the night
– Most useful measure for
integration analysis
• Factor of five difference
from energy metric
From: High Penetrations of Renewable Energy for Island Grids in Lilienthal, Power Engineering, November, 2007
http://www.homerenergy.com
26. Levels of renewable regimes
• More renewables requires:
• More intelligent controls
• Storage, electric or thermal
• Load management
Low No Special Controls
Medium Control excess renewables
High Re-dispatch diesels
Very high Operate diesel off
St. Paul, Alaska
http://www.homerenergy.com
28. Lessons from the Remote Market
• What to do when the wind blows too strongly
– Secondary loads
• What to do when it stops too abruptly
– Load management as “spinning” reserve
• What to do with storage
– Not just for load shifting
– Small grids need stabilization
– Technology is changing rapidly
http://www.homerenergy.com
29. Clean Power Evolution
• Large utilities
– Security obstacles
– Regulatory obstacles
• Smaller systems
– Liquid fuels from oil
– High renewable penetrations
Micro-grids with distributed controls for reliability and efficiency
http://www.homerenergy.com
31. Conclusions
• Too many choices
• Doing nothing is the worst choice
• Fully integrated hybrids provide high quality power
• Storage technology and costs are improving rapidly
– Still requires careful analysis
http://www.homerenergy.com