Let's Talk Energy
In Twitter we can only state things briefly, so, let's dive a little bit deeper concerning the global energy supply.
We won't discuss climate here since it rapidly turns into a quagmire. However, for the sake of argument, let's say reducing the CO2 intensity of our world energy supply is a worthwhile objective.
First, let's see where we stand today.
This is our global primary energy supply:
And then, even though electricity currently represents less than 20% of world final energy consumption, this is how electricity generation by source looks today:
Due to the fact that it is easier to replace fossil fuels in electricity generation than in primary energy overall, most of the energy discussions we listen to focus on electricity to the point that many persons confuse "electricity" with total primary energy. As we can see above, they are very different things. For example, in spite of oil barely being used for generating electricity it is comfortably the number one source of primary energy globally.
We should also underline that "easier" does not mean "easy."
So, once we understand where we stand today we can analyze how we could best move to a lower CO2 intensity in our primary energy.
If we focus on electricity, the IPCC lists these equivalent CO2 emissions per kWh by fuel:
1. Coal: 820 grams.
2. Natural gas: 490.
3. Hydro: 24.
4. Nuclear: 12.
5. Wind: 11.
6. Solar: 45.
Note: As we can see in the table above, no energy is "zero carbon." What is more, coal and natural gas emissions mostly happen throughout the life of those power plants, while nuclear, wind and solar emissions are mostly preemptive. This is an important difference.
Another thing we have to consider is the reliability of power plants. In general, coal, natural gas and nuclear power plants are reliable. Hydro, depending on geography, may be reliable, or partially reliable (in other words, it may have seasonal variations).
Solar and wind, on the other hand are intermittent sources of power that may produce little or nothing when energy is needed the most. Thus, solar and wind MUST be paired with reliable power plants. The best suited for this function are natural gas and hydro power plants. It would make no sense to pair "renewables" with nuclear as emissions would increase. Nuclear is better suited for 24/7/365 operations and stopping just for refueling.
Thus the effective, real life emissions of solar / wind farms are higher than indicated in the table above.
As an example, let's make some numbers for solar paired with natural gas. Let's say the solar annual capacity factor in a certain location is 15%. Thus, simplifying, natural gas will produce electricity 85% of the time. Thus, the weighted emissions per kWh would be: (45 grams x 15%) + (490 grams x 85%) = 423 grams per kWh. Sure, the capacity factors of solar and wind vary from location to location but they are always relatively low on an annual basis.
So yes, there is a reduction in emissions going from pure natural gas to solar + natural gas: 67 grams per kWh but this requires a double investment.
A better example is replacing coal with natural gas. Here the reduction amounts to 330 grams per kWh. Almost five times more than the example above.
And, sure, the best of all would be to replace coal with nuclear: a reduction of 808 grams per kWh. Twelve times better than the solar / gas example.
However, in real life, natural gas can replace coal much faster, and with less investment, than nuclear.
Here we can see what the USA has already achieved in this respect (the graph below is primary energy, not only electricity, but we get the picture):
China is consuming such gargantuan amounts of coal that it skews global statistics, however, if we remove China, this is how the world looks like (including the USA):
We can clearly see that the transition toward natural gas is gaining momentum globally.
Sure, ultimately nuclear will need to produce most world electricity if we truly strive for significantly lower CO2 intensity in our electrical power. But in real life, this transition will be slow.
Without a single exception all top 10 electricity generating nations currently produce nuclear electricity. Yes, Germany is included here.
According to the iea, these are the CO2 emissions that have already been prevented by nuclear energy:
Sure, there will be a place for more dams (although hydro has nearly maxed out globally), solar panels, wind turbines and other niche technologies but if we truly want to move to a lower CO2 world economy, natural gas and nuclear will have to shoulder most of our energy weight.
This article has mostly focused on electricity (~20% of our final energy consumption) because, as mentioned, replacing fossil fuels in electricity generation is easier (but not easy) vs. replacing them in the rest of our final energy consumption (~80%).
The "80%" will be the subject of a future post.
Thank you very much and please feel free to add to the conversation in Twitter and not here in Blogger.
My handle is @luisbaram