Climate change is one of the pressing issues of our time. However, there has been far too little down in order to combat it. But building a low-carbon society is possible, and we already have the technology to do it.
A lot goes into a low carbon society, but today I'm going to focus on how we can produce electricity from clean sources.
What Are The Options?
According to the IPCC, electricity sources have the following emissions by source:
| Source | Emissions (cCO2eq/kWh) |
|---|---|
| Coal | 820 |
| Natural Gas | 490 |
| Biomass | 230 |
| Coal With CCS* | 210 |
| Gas With CCS* | 170 |
| Solar PV | 48 |
| Geothermal | 38 |
| Concentrated Solar Plant (CSP) | 28 |
| Hydropower | 24 |
| Nuclear | 12 |
| Wind | 11 |
*CCS is Carbon Capture and Sequestrian
Every source out there, even technically "emission free" sources, produces emissions of some degree due to the creation, construction, and transportation of materials. However, we have to draw a line in the sand somewhere.
The most logical place to me seems to be the large gap between Solar PV and Gas With CCS - meaning Solar PV is the highest emission source we will accept.
Factors To Consider
Since we've already considered emissions, what else are we going to have to look at in order to build our grid? There is a couple key factors to consider:
- Cost
- Availability of resources
- Flexibility/feasability
Together, we have to safely account for all of these factors to construct a successful low-carbon grid. Let's simply apply these factors to determine where our advantages and disadvantages lie. Cost data comes from a Lazard analysis here.
Solar PV
Pros
- Low cost
- High availability
Cons
- Very low flexibility and reliability
Geothermal
Pros
- Relatively cost-effective
- Very high reliability and flexibility
Cons
- Limited geographic availability
CSP
Pros
- Decent availability
- Somewhat flexible
Cons
- Above average cost
Hydropower
Pros
- Reasonably cost-effective
- Highly flexible
Cons
- Some potential, but also limited
Nuclear
Pros
- Very reliable
- Mostly available, little geographic restrictions
Cons
- Very high cost
Wind
Pros
- Low cost
- Good availability
Cons
- Low flexibility and reliability
Building Our Grid
How typical electricity demand is structured
Now, the most important thing to accomplish is to have a stable, balanced grid that can always match supply with demand. We need to be able to create a grid that can do that at the lowest cost possible.
Let's start with wind and solar energy. In terms of cost, these two sources are the low hanging fruit. Experts disagree on how much power these two sources can provide, and credible estimates range from 25% to 80%. Since these are our lowest cost options, we typically want them to contribute as much as they can. With that being said, the more electricity they contribute, the higher the costs to "integrate" them are (meaning they place a cost burden on the rest of the electricity system in order to accommodate their variability).
Taking a middle of the range, possibly a little bit conservative, estimate we'll guess they are able to meet 40% of electricity demand combined. This should provide a cost-effective source of power that can still be accounted for with the remaining sources.
We now have 60% of the electricity demand to meet with the remaining sources, so what do we turn to next? While our grid has some low cost variable sources, what it desperately needs is flexibility to help accommodate these variable resources.
The two logical sources are hydropower and geothermal. Both sources are reliable, they can produce at a consistent level for long periods of time. And both sources are dispatchable, they can easily alter their output in order to match demand changes or supply changes from variable sources. Both of these sources are also relatively cost effective.
However, both of these sources are constrained by geography. Some countries derive the majority of their power from them, others get almost none. The availability of these sources varies wildly by location. However, we will assume our theoretical grid can get 25% of its power from them. With the introduction of small hydro, greater hydropower resources for now available for utilization.
Next, we have Concentrated Solar Power, or CSP. CSP is notable for having built-in storage of up to 24 hours. This makes it fully dispatchable, but it's not as reliable as hydropower or geothermal since it still relies on heat from the sun, which varies through-out the year and even on a day-to-day basis. CSP is kind of a wildcard, but we'll assume it is able to meet 5% of demand. That leaves us with 70% of electricity demand covered thus far.
Lastly, that leaves us with nuclear energy to cover the remaining 30%. Nuclear energy can be deployed at scale almost anywhere, which makes it viable to complete our grid. However, it is expensive. We can mitigate that, however, by allowing our nuclear energy to cover baseload power needs (demand that always exists). The consistent power output and high capacity factor allows nuclear energy to function in the environment it's best in, and makes the electricity much more affordable. In short, here is what our grid looks like:
| Source | Percentage |
|---|---|
| Wind | 20 |
| Solar | 20 |
| Hydropower | 20 |
| Geothermal | 5 |
| CSP | 5 |
| Nuclear | 30 |
And there we have a 100% clean grid. This grid would emit only about 10% of the emissions of a typical grid today.