"I only know that I know nothing", Socrates.
This week I am exploring questions that I have about greentech. Some questions may have a simple answer and some may be just rhetorical questions. Perhaps by next week you (the reader) will provide some answers and shine some light into this darkness. So here it is:
When I heard the debate last week, as well as in previous debates, the subject about alternative energy was present. Both candidates agree that new sources of energy are needed (I don't want to start a political discussion, so let's focus on the big picture) with some differences here and there. Both candidates talk about Nuclear power, but NEITHER CANDIDATE ADDRESSES THE DANGERS of this kind of energy source.
It is my understanding that the biggest problem with Nuclear power is the use and disposal of the radioactive fuel. I have heard (and here is my first question) that nuclear plants use less than 5% of the radioactive material power, is this true? And then, we are left with highly dangerous waste that takes over 10,000 years to become safe? To make things more complicated I have also heard that if we increase the percentage of world power generated by nuclear plants we will have no space left to safely store this radioactive material, could this be?
Why is Belgium, a country that generates 54% of its electricity through Nuclear plants, trying to stop construction of new plants and setting additional tax to existing nuclear power generation. Belgium, as well as Germany, the Netherlands and Sweden have all pledged to phase out existing plants. Why?
I would very much like to know the answers to these questions before we embark on a journey that may lead us into a global disaster!
Let's forget about Nuclear power for a second, let’s focus on a wider subject. How are we going to find a way to generate energy without draining the resources that we have in Planet Earth and without polluting our environment?
I guess most of us agree that the current way we generate energy and dispose our waste is dangerous for our future (please note I said: "most of us". "Why is this so?" is a question I will not ask here, for now).
In order to search for an answer on energy efficiency we need to look at the laws of thermodynamics. The first law states that "Energy can neither be created nor destroyed. It can only change forms". Therefore, we will be better off if we try to use energy that comes from outside our planet: Solar energy. Right?
Well Solar energy is the direct consequence of the power of the sun that enters the earth. But waves, wind and tides (I'm not sure about geothermal) are also partly or wholly a consequence of the sun's effect. So, if we choose wind over solar power, are we selecting an indirect source of power and therefore sacrificing efficiency?
In evaluating an energy source we need to look at two factors: (1) how much energy can we "capture"? And (2) How much energy are we going to waste in the conversion process to its "final destination". And finally compare these numbers to the associated costs in order to find the best solution.
(1) Energy "capture": Solar energy is hard to capture, current solar cells can only attain around 8% efficiency. Other cells are able to convert up to over 40% of the sun’s power, but the cost of the materials used in such cells is prohibitive. Never mind that solar cells depend on the exposure to the sun and therefore are useless at night or with minimum light conditions. Why can’t we have both efficiency and low cost? Is 40% the best we can do?
Wind power has a theoretical limit of 59%. This means that the best wind and the best turbine in the world can only obtain 59% of the energy contained in wind (which already is a factor of the energy coming from the sun!). Can we have wind as our main source of energy with a ceiling of 59% efficiency?
(2) Conversion process: It's not enough that solar cells are inefficient within themselves, the process to convert direct current (DC) obtained with the cells into alternative current (AC) requires inverters which eat up between 5 and 50% of the electricity generated. Wind has a similar problem; the rotation generated by the wind has to be converted into a faster rotation speed to match the frequency on the electricity in the grid. This conversion lowers the efficiency of the turbine. Can we find a system that minimizes the loss of power in the conversion process?
Cost: No alternative energy source up to date has an associated cost that can compete with fossil fuels. Right? These sources depend on government subsidies; the idea is to promote economies of scale until they become competitive. Is there ever going to come a day when alternative, sustainable energy is less expensive than coal?
Wind and sun are variable sources; storage needs to be added to the system to make it work. Supposedly one of the most efficient ways to store energy is by pumping water into a high level storage, and later using the water's falling energy to regain the stored energy (this system achieves about 75% efficiency). Can we use such a system in a large scale alternative power generator?
As for Wave and Tide power generation technologies we have yet a long way to go, those areas are far behind wind and solar. Are we doomed to use fossil fuels until they run out?
In the alternative fuel vehicle arena, the argument of many proponents includes the following statement: "We use less than 25% of the gas in the car to generate forward motion" (the rest of the fuel is spent on noise, electric gadgets, pollution, etc). Can this be?
If the efficiency of current vehicles is so low, how come we have not been able to create a more efficient car in a shorter timeframe?
Finally (I am running out of space), I have trouble understanding the logic behind Hydrogen. Why are some people proposing hydrogen as a fuel? Supposedly hydrogen is a great storage media for electricity. The simplified principle is as follows: add electricity to water and you get hydrogen; turn the system around and release the electricity and obtain water back. Well, using the second law of thermodynamics the amount of electricity released from the hydrogen can only be the as much as the electricity injected in the water. This is power storage not fuel!?
I know that many of you will disagree with some of the ideas explained above, please give me your point of view! I also know that some concepts are explained superfluously, unfortunately I have limited time for this blog, and if I get enough requests I may write a book in the future (just kidding!).
Before leaving, I have to announce this week’s big news: I am father of a baby girl, Dana! (my third child).
Until next week: SHALOM!
