24.01.2011 lecture diary

If the lecture starts with the mention that some of the lecture slides will be skipped due to lack of time, then wouldn’t you think that it means that we have too many slides crammed into too little space? I know I did.

Mentioning that PVs work best in places with lots of radiation and low temperatures made me understand why they are so popular in the space applications. Also, I’m curious about using water cooling in PVs. If they work better cooled, wouldn’t this be the natural next step? I know that on the lecture it was mentioned that combined PV and heat production was for some reason unpopular, but it wasn’t too well explained why.

In the solar thermal section we had tons of formulas, of which most were skimmed through. I think this would be a good section to go through again and remove much of the chaff in order to make the whole package more compact.

When we were talking about sizing of solar thermal collectors, I’d like to know how much warm water e.g. a warm shower or bath takes. That would really help me understand how much energy we’re using during our daily life without really realizing it.

When talking about wind power, it was mentioned that it should be observed locally for years in order to get some information about how much wind can be expected. Couldn’t this be circumvented at least partially by using data from nearby similiar locations? Or wind data and the geographical data from the surroundings? Would this require too much computation so that this approach isn’t feasible even with the modern supercomputers?

It was also said that a wind power system should be used with another system. Or that as a rule of thumb there shouldn’t be more wind power than 20% of the total power need. There’s actually one way to at least partially circumvent this unless the system is extremely small: not using all the wind power produced to supply the load, but instead dumping some of it, and when the production oscillates, we use that extra power to buffer those changes. Sure, it won’t help us when we have no wind, but it sure does some good to even out those spikes and low points in the wind energy production.

If the wind turbine furls, does its power production drop to zero or does it just reduce its power production by some amount?

The 15 or so pages relating to the hydropower seemed to be mostly repetition of lecture one, so I’d recommend a rewrite here. The pico hydro was interesting, since I hadn’t yet heard about a 200 watt power plant.

Why is the water pumping using the electricity so important? Couldn’t the same be achieved with less uncertainty due to breaking parts using human and/or animal power? Or is it just a good way to dump that extra electricity during the windy or sunny days when nobody needs the lighting during the day, and we have already the wind or solar power system installed?