There are some very widespread and incorrect conceptions about renewable energy sources. I mention and discuss some of the most common ones below.
1. Solar panels and wind turbines are not efficient enough to be viable sources of electricity. Their efficiency needs to amount to at least that of conventional power plants.
I am not denying that there are problems associated with both types of generators, but their problems are not primarily efficiency related. The worst problem with wind right now is the fact that it requires cheap energy storage to store power generated intermittently by wind turbines, especially at night, for future use. Especially to meet peak electricity demand. Wind turbine efficiency varies from 30%-50%. This range is considerably more than traditional fossil fueled generators which are in the 25%-38% range. Solar panels, on the other hand have an average efficiency range of 10%-22%. Solar thermal power plants exceed 30%.
A power plant’s efficiency could exceed 70% and it could still be an expensive source of electricity. It is one of many important factors that determine cost.
2. Not much energy can be harvested from the sun nor wind.
The percentage of energy in the United States, for example, which can come from traditional wind and solar power plants is limited by their intermittency, not the amount of electricity they can produce, nor a lack of wind or sunlight. This is because you cannot rely on electricity directly from solar panels or wind turbines alone without some form of buffer or energy storage because when the wind stops blowing, there is no power. Therefore, the wind turbine needs to charge an energy storage system which would then supply electricity to consumers all the time, and without fluctuations and interruptions. When it becomes cloudy, solar panel power output drops. My point is that they can be used to help power homes, but if residents rely on them directly for more than a certain percentage of their electricity, they could end up with shortages and/or blackouts.
Another important point is that solar cells can be integrated into everything now due to thin film technology. Many devices can and in the future will generate their own electricity, reducing the number of solar and wind power plants as well as residential solar setups required.
3. Fossil fuels will continue to dominate for decades to come because renewable sources of energy are far too costly.
First of all, you should not generalize fossil fuels nor renewable sources of energy like that, their costs vary significantly. Hydroelectric power is renewable, and it is affordable (2-5 cents/kWh), the case is the same for geothermal (5-8 cents/kWh) and waste to energy. There are also different types of solar power plants and their costs vary, such as solar thermal steam, solar stirling, and photovoltaic (which consists of the solar panels that you are most familiar with, 16 cents/kWh). Coal is cheap (6.2 cents/kWh in 2009) but another common fossil fuel which is cheaper than gasoline, is actually very costly as a source of electricity, far more costly. Natural gas is also a fossil fuel.
Problem Two: The cost of all of the fossil fuels normally follows an upward trend, and the cost of solar power normally follows a downward trend. All of the major fossil fuels are on the road to a dead end because they are finite resources, and they will arrive very quickly.
4. Solar and wind power plants take up too much space and would have to cover the earth just to meet electricity demand.
Dwindling fossil fuel reserves widen the gap in total long term generation capacity of renewable generators and fossil fuels in general:
Due to the fact that the sun and wind are renewable sources of energy, this means that you cannot run out of them. There will always be sunlight and wind available as long as mankind exists. Wind and solar energy resources do not dwindle as people use them like fossil fuels do.
Farm land sharing for wind:
Wind farms occupy plenty of space per watt of electricity that they can generate, but that is because wind turbines have to be spaced. Most of the space on a wind farm is available for farm use, and sometimes wind turbines are used on farms. The amount of ground space physically occupied by the turbines themselves is very little.
Generators which are powered by fuels, particularly coal, uranium, and other solid fuels require continuous mining in order for a continuous supply of fuel to the generators to be possible. Continuous mining of solid fuels, equals the eventual expansion of mining operations to other mines to meet demand if the first mine does not have enough left, and mines occupy land which cannot be used for other purposes like wind farms can. Furthermore, when a solar or wind power plant reaches the end of its life, the panels and turbines are removed and the land is still usable for everything, so it is not wasted/destroyed like mined land.
Solar panel integration into items:
When solar panels are integrated into items (and they will be more in the future), they occupy no land. No other type of generator has this quality. This was made possible with the advent of thin film solar cells.
5. You have to purchase a lot of extra solar panels and extra batteries due to the variability of weather:
No, you can use a transfer switch.
The transfer switch I am referring to is a device which switches appliances over to the electricity grid when there is a shortage of electricity so that you will not have to purchase any extra batteries nor solar panels. I should also add that you can use very few batteries as a buffer for solar power with a transfer switch and use them to power the house or whichever appliances you choose during the day only. The size and cost of such a setup is nowhere near that of a traditional setup, but the drawback is that you would have to pay for night time electricity which is cheaper in some areas due to off-peak pricing. At least you could curtail your daytime power consumption using solar panels and few batteries. Many businesses whose opening hours are almost all during the day could benefit from such a setup tremendously.
6. The real cost of wind power is actually high because wind turbines generate far less than their rated power on average, which means that their capacity factor is low.
The cost of wind power is 4.6 cents/kWh. If you were to assume that this cost was without factoring in the capacity factor, which is the percentage of the rated power that the turbines generate over a given period of time, and that the capacity factor was a low 30%. This would mean that the turbine would generate only 30% of the specified power rating, and the cost of electricity from such a turbine would be an average of only 7.8 cents/kWh. In other words, you could conservatively assume that the $0.046/kWh cost does not include the capacity factor and multiply it by 1.7 which is 170% of the 4.6 cents, and wind power would still only cost 7.8 cents/kWh, or $0.078/kWh.
Photo via MrsMinifig