Friday, January 18, 2013

Is Hydrogen a Viable Alternative?

Feelings, feelings and more feelings are what we see in many energy discussions. If we are talking about religion or maybe even about politics, it is OK to mix as much feelings as we want, but not when we are talking about energy. In this subject we should stay cozy to the facts, the laws of physics and yes, economics. 

Can renewable energy provide 100% of our energy? Yes but at a prohibitive cost. Consequently renewables are not really a total solution (yes, they have their place in our energy mix but their penetration is and will continue to be quite modest in a global scale).

For example, some renewable enthusiasts mention that excess electricity produced by the sun can be converted into hydrogen and then burned when we need the power. 

Technically this is 100% feasible, but economically... 

1. A say, one megawatt solar installation in a nice and sunny place produces on an annual basis only close to 200 kW average power (five times less than the "plate" rating).
2. The efficiency of electrolysis (to produce the hydrogen) is around 70%.
3. The efficiency of the hydrogen turbine (to move the generator) is probably less than 50%.
4. The efficiency of the generator should be in the order of 90%.
So, just the last three steps above result in a combined efficiency of 31.5%. In other words, 68.5% of the energy produced by the solar panels is lost in this hydrogen conversion process! And you still have to add the capital expenditures of the electrolysis plant, turbines, generators, storage tanks, etc. It makes absolutely no sense. 

Besides we wouldn't have to beat so much around the bush, there is something called rechargeable batteries with much better conversion efficiencies than the above. We could use them to store the excess electricity, but again it requires considerable investment that will impact the cost of the electricity produced: the batteries themselves, the inverters, warehouses, replacement of the batteries every so often, etc., etc. And sure, it is not particularly "green" to produce and then dispose of so many batteries. Even then if the sky were cloudy for several days the batteries would be completely depleted and conventional energy will have to come to the rescue. In other words, solar (or wind) cannot really replace conventional power plants.

Let's face it, the reason renewables require subsidies to survive is because they are more expensive than conventional energy and, specially, that they fully depend on the conventional electrical grid. 

So, let's not talk about wishes, let's talk about facts: when Japan shut down its nuclear plants after the tsunami almost 100% of the replacement energy came from fossil fuels. That's right: not solar, not wind but fossil fuels. They imported more coal, more natural gas and more oil. Their emissions went up and their balance of trade suffered. These are the FACTS. Not the wishes.

Now Germany is embarking in a very expensive renewable experiment and the only reason Germany will not go exactly the way of Japan (that is in substituting all nuclear with fossil fuels) is that France and other neighboring countries will gladly sell them nuclear electricity. Sure, German carbon emissions will go up (because they will increase their coal and natural gas use in generating electricity) but not as much as could be expected if France were not there to help.

As we all know the country at the center of the nuclear hurricane, Japan, is already re-starting its nuclear plants. It is time for all of us to also stop running away scared from nuclear power.

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