Solar vs. Wind Energy

[zach]

I'm curious what the benefits (pros) and costs (cons) of each are.

Also wondering what the payback time is on an investment in solar vs. wind.

Solar
Con: I've heard some of the materials used in solar panels are procured through strip mining and are pretty caustic.
Con: Batteries needed to store energy at night or when it's cloudy.
Pro: Less intrusive than big wind turbines.

Wind
Con: Noise
Con: Bird Hazard
Pro: Generates day or night as long as the wind is blowing.

[Marc2]

In general, batteries are needed for both solar and wind power because neither of these provide constant power.

Advantages of solar:
- Almost maintenance free (once setup)
- Easily scalable (It is easy to add solar panels to an existing system).

Disadvantages of solar:
- higher cost
- The production of solar panels consume more resources

Advantages of wind:
- lower cost
- More power is usually available from wind than from solar
- Higher efficiency for the larger turbines (although friction is significant for the smaller turbines lowering their efficiency).

In general you would have solar power for small amounts of power (like a small number of electronic devices). Even more so, if the location is remote like weather monitoring stations or satelites.

Wind would be the better option if you want to produce a significant amount of power. Wind farms would be better than solar farms if replacing power plants.

If you want to power a home, I believe that wind is probably still the most cost-effective method unless you consume a very small amount of power.

[Karl]

Originally Posted by zach

Wind
Con: Noise
Con: Bird Hazard
Pro: Generates day or night as long as the wind is blowing.

The most frequently cited objections to wind turbines seems to be noise and the potential impacts on birds. But other issues have included aesthetics (their perceived intrusiveness on the landscape) as well as "shadow flicker" which was raised in this video

However, the main issue that restricts the use of wind energy (using existing methods of harvesting) are its relatively low efficiency and more important - the unreliable nature of the resource. Unlike tide energy (which can be predicted accurately) wind is extremely intermittent and shows considerable variability in wind speed, intensity, duration (and even wind direction).

The intermittency of the wind is what rules out many locations from having wind turbines, and even where the (measured) wind patterns demonstrate its feasibility, there will always be "down time" when the wind is insufficient (and these are difficult if not impossible to accurately predict).

As a result of its intermittent poorly predictable nature, wind can make a useful contribution as a supplementary electricity source, but using the current turbine designs, it remains unlikely that it could ever be dominant. These problems of intermittency are less likely for wind farms in offshore locations, since the lower friction associated with the sea surface (in comparison to wind blowing over the land surface) results in less problems with source variability; however, the installation and maintenance costs are higher for the offshore windfarms, and they are likely to be located further away from existing electricity grids.

Notwithstanding these factors, there is ongoing research into alleviating some of the problems of wind power including noise and voltage dips

Further to this, for smaller scale production, there have been some research developments in "non-turbine" wind generation. It remains to be seen how these perform in relation to efficiency / intermittency...

> Non-Turbine Wind Generator | Green Tech Gazette

> Vaneless ion wind generator - Wikipedia, the free encyclopedia

[Karl]

Then again, apart from the problems when the wind is not strong enough, sometimes there are also issues when the wind is too strong...

> YouTube - A Vestas wind system fail and crashes.

[Karl]

Originally Posted by zach

Solar
Con: I've heard some of the materials used in solar panels are procured through strip mining and are pretty caustic.
Con: Batteries needed to store energy at night or when it's cloudy.
Pro: Less intrusive than big wind turbines.

Everything used in human activities has to come from "somewhere" (extracted from the environment).

So it is inevitable that the production and use of solar technology will have an environmental impact. However, that is also true of all other systems used for energy generation, distribution and consumption (whether from renewable or non-renewable sources). The most important issue is a comparison, for each available energy option, of how the technology's performance balances against its various environmental "footprints".

As such, even though there are potential impacts to the environment from using solar energy sources, the most important issue is how this compares to other sources of energy, and how the identified impacts can be reduced, controlled and mitigated.

Even though the production of the technology may affect the environment, and they have limitations for their use (day-time only; sufficient solar intensity, etc.) requiring the use of storage (batteries) -- the main advantage is the lack of pollution or GHG emissions associated with their actual operation.

Another positive of solar is the devices that the actual maintenance should also be simpler. A wind energy conversion system is structurally more complex and is mechanically-based, as compared to, for example, a photovoltaic system which is based on electronics and electrical systems (solar radiation converted to electricity by semi-conductors). Devices using solar energy for direct heating (e.g. water heaters, crop dryers) would have even less maintenance issues.

Related: “Spatial Footprint” Challenges of Solar Energy Use « GEO ENERGY NETWORK

[Karl]

Some more articles on the advantages and disadvantages of both solar power and wind power...

> Advantages of Solar Power Vs Disadvantages of Solar Power

> Wind Energy - Advantage of Wind Power Vs Disadvantages of Wind Power

[zach]

I was listening to someone on NPR yesterday and they were saying that Wind Power is much less efficient for small single home power generation than it is for large scale wind farms because of the friction involved in turning the turbine and getting it moving.

Another thing I didn't really think of when posting this was that solar can also be used to generate heat for home heating and hot water which I would think is more efficient than converting solar or wind energy to electricity then converting it to heat. Still has the limitation of only working when the sun is shining but may reduce the need for electricity and gain some efficiency.

[Karl]

In terms of the feasibility (and thus, payback time) -- that should vary with geographic location, and the differences in average wind speed, solar intensity, altitude etc.

Some energy resource maps for solar and wind...

Wind Speeds

> Global wind power at 80 m

> Wind Energy: NASA Wind Map Shows You Where The Greatest Gusts Blow

> Wind Energy Resource Atlas of the United States

Solar Radiation intensity

> http://cleantechnica.com/files/2008/10/wh_solar.jpg

> Solar Insolation Map - World - AltE

> Solar Insolation Map - USA - AltE

> Solar Insolation Map - South America - AltE

[zach]

Thanks Karl! Your are full or good info!

[william]

Good points, here is a few more that I can think of..

Grid connect systems eliminate the need for batteries if you are in such an area.

Not sure about solar to battery storage, but in PV grid connect you can't just add panels, you would also need to upgrade the inverter. The inverter makes up about 15% the cost of a 1 kW system btw. (wholesale price anyway) I suppose you could trade in/recycle it when you upgrade.

There are vertical wind turbines. The birds don't fly into them as they always look like a solid structure, unlike traditional windmill style ones. There are styles that are shaped to a point and that blend in nicely with a roof line. Also as far as the manufacturers claim, they are whisper quiet. Wind can work 24 hours a day.

Sorry I can't find a link to the vertical pointy turbines, but the one at the end of this video is sort of close to what I mean by vertical. ie. a bird would not fly into that design unless it was crazy. :-O
YouTube - VERTICAL AXIS WIND TURBINE WINDMILL ALTERNATIVE GREEN POWER