Tuesday, April 15, 2014

Energy: Let's Do Our Homework

Energy is a complex subject in which many variables intervene and thus we do have to make our homework to choose wisely.

In the energy discourse we still see oversimplifications in which energy is divided into "dirty" and "clean." Discussions at that shallow level are not useful for establishing energy policy or even for educating the world on the difficult decisions we have to make.

With this article we want to motivate a quest for deeper understanding and the application of more reason and less feelings in this all important subject.

Let us first start by stating that there is no such thing as clean energy. When considering their full life-cycle, even the cleanest sources (hydro, wind and nuclear) have greenhouse gas (GHG) emissions and create other types of wastes that impact the environment. So, here are some of the things we should be asking ourselves:

1. What are the carbon emissions per kWh of the specific energy source (including all processes from cradle to grave)?
2. Is the energy reliable?
3. If it is not reliable, how are we going to compensate for its unreliability (other reliable energy will cover the lulls or would storage be used)?
4. If other forms of energy cover the lulls, then these emissions need to be considered in the emissions of the "system."
5. If storage will be used, we also need to consider the GHG emitted in the cradle to grave processes of the storage technology and add it to the emissions of the "system." Also, how many hours / days / weeks of energy do we plan to store? How much storage area would be required for the banks of batteries or other storage technologies? What is the leasing cost of this space?
6. Emissions are obviously not the only variable we need to be concerned about, resources utilization and costs have to also be high in the list.
7. What are the capacity factors of the different technologies in the specific place where we are planning to locate them?
8. Is it advisable to combine several types of renewable energy to somewhat compensate for the peaks and valleys in electricity generation? If so, say, how much solar capacity and how much wind capacity should be installed?
9. Should we go "all out" for a particular technology or only as much as makes financial / environmental sense?
10. Could climate change seriously modify our design assumptions in the short / medium term (e.g. less / more wind in a particular place on Earth)?
11. How much intermittency can the current grid absorb? Are additional investments required in the grid so it will be able to handle high penetrations of intermittent energy?
12. What type of investments would achieve the most bang for the buck (in other words, the best reduction in emissions)?

The above questions are just to get the conversation started.

The next step would be to model the complete system and calculate (among many other things) these two all important parameters:

1. Cost per kWh of the generated electricity.
2. Emissions per kWh of the system.

If either of the above is too high, we may need to go back to the drawing board until an acceptable system is designed.

Again, the purpose of this article is to make people realize that energy is a very complex subject and it is better to leave it to the engineers to design energy systems. Many times well intentioned but naive persons want to lead the energy discourse and this can take us to the wrong results: high cost / high emission systems.

Thank you.

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At 11:15 AM, Blogger Walt Heenan said...

Great summary. Especially the observation that the dirty/clean energy is a false dichotomy. Thanks.


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