Podcast Summary: Making Large Scale Wind and Solar Power a Reality – Kevin Ummel

Podcast: The CGD Podcast
Host: Center for Global Development (Lawrence MacDonald)
Guest: Kevin Ummel, Visiting Senior Associate, Center for Global Development
Date: November 25, 2013
Episode Focus: How to make large-scale wind and solar power work in developing countries, with a deep dive into spatio-temporal modeling for optimal deployment, using South Africa as a case study.

Episode Overview

In this episode, host Lawrence MacDonald interviews Kevin Ummel about his new research paper on large-scale wind and solar power planning in South Africa. They discuss why simple “sunny and windy spots” logic isn't sufficient for power planning, the challenges and costs posed by renewable intermittency, how advanced spatial-temporal modeling can reduce costs and increase reliability, and the broader implications for energy policy in developing and developed countries. The conversation is both technical and accessible, using analogies and real-world examples to unpack a complex subject.

Key Discussion Points & Insights

1. The Central Challenge: Intermittency and Cost

Timestamps: 01:55–07:49

• Main problem: As countries increase wind and solar penetration, the fact that these sources are intermittent (not always generating when needed) creates both reliability and cost challenges.
  • “Wind and solar power have all sorts of advantages, but there's two big drawbacks. The first is cost, which we're all aware of. And the second is this thing called intermittency.” (B, 01:55)
• Low initial renewable penetration: At low levels, these issues are minor, but as penetration hits 20%+, they become major.
• Coal and renewables: Countries like South Africa depend heavily on coal (>90%). Coal is poorly suited as a backup for intermittent renewables due to its slow response time, unlike gas.
  • “Gas plays much better. It's able to fluctuate over time to help smooth out the wind and solar.” (B, 04:00)
• Rising costs: Electricity prices in South Africa are climbing (not solely due to renewables), creating political hurdles.
• Reliability crises: South Africa has suffered from blackouts, and poor renewable integration could worsen these issues.

2. The Real Costs of Renewables

Timestamps: 07:14–09:03

• Dispatchable vs. intermittent: Replacing steady “dispatchable” sources (coal/gas) with intermittent ones always pushes up system costs.
  • “The environmental community has not liked to admit this, but ... you by definition increase the cost of running the power system reliably.” (B, 07:14)
• Storage limitations: Pumped hydro is promising but geographically limited; batteries are still too expensive for grid-scale needs.
  • “Battery technology is really too expensive to use for this Type of thing.” (B, 07:59)
  • “It's just much more cost effective to use natural gas.” (B, 08:50)

3. Modeling an Optimal Renewable Rollout

Timestamps: 10:40–16:24

• South Africa’s targets: 20% renewables by 2030; plans for 40% by 2040.
• Rubik’s Cube analogy: Planning an energy grid with high renewables is like solving a Rubik's cube where many squares change colors—extremely complex.
  • “Solving a traditional Rubik's Cube is a bit like planning a conventional power system ... Now imagine 40 or 50% [of squares] were changing color. That's like planning a high penetration wind and solar power system.” (B, 11:42)
• Data-intensive approach: Used high-resolution NASA, European, and weather model data to simulate how different renewable technologies would perform, hour by hour, across South Africa’s diverse terrain for 10 years.
  • “We can take that massive amount of data and put it into a model that says, okay, how should we arrange these technologies across space to provide electricity reliably at the lowest cost?” (B, 12:53)

4. Other Factors in Planning

Timestamps: 14:23–15:19

• Screening layers: Consideration of biodiversity, human settlements, existing grid locations, and soil—non-energy factors that restrict project siting.
  • “There’s an extensive…terrain screening layer…screens out places like national parks or game reserves, places where the soil is insufficient.” (B, 15:01)

5. Key Results from the Modeling

Timestamps: 15:36–19:07

• Traditional vs. optimal placement: Using a traditional approach, South Africa could achieve 40% renewable capacity by 2040 at ~$26/ton CO₂ abatement cost.
  • “South Africa could hit 40% penetration by 2040 with an abatement cost of about $26.5.” (B, 16:36)
• Optimized placement: By simply redistributing the same capacity spatially, abatement costs could fall by 15%.
  • “We can reduce the abatement cost by almost 15%, not by changing the amount...” (B, 16:49)
• Optimized technology mix: Allowing the model to choose both technology types and locations, costs can drop by 40%—primarily by prioritizing photovoltaics (PV) and using gas for night-time peaks.
  • “We can reduce abatement costs by 40% compared to the traditional way of planning.” (B, 18:18)

6. Surprising Insights on Technology Choices

Timestamps: 19:07–20:59

• PV vs. CSP: Contrary to some expectations, the model chose heavy use of PV (solar panels) over concentrated solar power (CSP). This results from assumed rapid future PV cost declines and the cost-effectiveness of pairing daytime PV with nighttime natural gas.
  • “It was actually better off to just use a lot of photovoltaics and then introduce more natural gas to provide electricity during those evening periods.” (B, 19:52)

7. Practical Policy Implications & Next Steps

Timestamps: 21:21–26:18

• Replicability: The method, though less sophisticated than giant US studies, could enable developing countries with modest means to get actionable, early guidance for grid planning.
  • “I'd like to see a capability for countries everywhere to do low cost, not as high quality, but do low cost initial modeling of this kind…” (B, 22:24)
• Plan for uncertainty: Ummel stresses that planners should keep as many options open as possible, building robust, flexible systems—similar to prudent retirement planning.
  • “Develop deployment strategies and transmission, build out plans that leave open as many low cost possibilities as we can...” (B, 24:00)
  • “If we make bad choices now...we may effectively close off opportunities 20 or 30 years down the road.” (B, 24:44)
• Infrastructure is long-lived: Decisions made now about where to lay transmission and place generation have consequences for decades.
  • “That infrastructure is going to be there for 60 years...So we should try to build things out in a way that leave open as many options as possible.” (B, 25:37)

8. Closing Thoughts and Looking Regional

Timestamps: 27:44–29:54

• Political and practical barriers: Current decision-makers and utilities may lack incentives or ability to radically change planning processes.
  • “The people who want to do power planning don't have much incentive to do it differently because they don't have the tools…or the political incentives.” (B, 27:44)
• Regional integration: The big opportunity may be creating a southern Africa-wide grid that harnesses the best renewable resources (wind, hydro, solar) across borders.
  • “How can we develop a larger southern Africa grid that effectively shares all the renewable resources…with a built out transmission system?” (B, 28:54)

Notable Quotes

• On the core problem:
  “Anytime you take what we call a dispatchable source of electricity, like coal or gas, and you replace it with an intermittent source like wind or solar, you by definition increase the cost of running the power system reliably.” — Kevin Ummel (07:14)

• On modeling complexity:
  “Now imagine 40 or 50% [of squares] were doing that [changing color]. It's a psychedelic Rubik's cube. That's like planning a high penetration wind and solar power system. Very, very complex.” — Kevin Ummel (11:42)

• On optimal placement savings:
  “We can reduce the abatement cost by almost 15%, not by changing the amount of wind power, the amount of solar power, just by changing where it's located spatially.” — Kevin Ummel (16:49)

• On leaving options open:
  “Try to develop deployment strategies and transmission, build out plans that leave open as many low cost possibilities as we can so that as we move forward and learn more, we have the ability to go down those paths that make the most sense.” — Kevin Ummel (24:05)

• On region-wide solutions:
  “How can we develop a larger southern Africa grid that effectively shares all the renewable resources, hydro, wind, solar, that are fabulous across the region, but shares them with a built out transmission system?” — Kevin Ummel (28:54)

Important Segment Timestamps

• Problem explained: Intermittency and cost – 01:55–07:49
• Storage and grid flexibility limits – 07:49–09:03
• Modeling approach and data – 10:40–14:23
• Terrain and non-energy site considerations – 14:23–15:19
• Abatement cost findings & optimal planning – 15:36–19:07
• Photovoltaics vs CSP result – 19:07–20:59
• Broader implications and flexible planning – 21:21–26:18
• Regional grid vision & political barriers – 27:44–29:54

Conclusion

This episode makes a compelling case for why sophisticated, data-driven spatial and temporal planning is essential as countries set increasingly aggressive renewable energy goals. Ummel demonstrates that how and where renewables are deployed can cut costs dramatically, even without changing the scale of ambition, and that flexibility and careful planning today are crucial for maximizing long-term gains and avoiding dead ends. The conversation offers lessons not only for South Africa but for any region mapping out a path to major decarbonization.