Solar and Wind

I often see articles about renewable energy where "solar and wind" are grouped as the main alternatives. This is misleading as there is a big difference in the underlying economics. Wind is about 5x more cost effective at producing electricity than solar PV. Wind has a real chance of making a meaningful contribution to our energy situation over the next couple of decades, PV does not. It's misleading to mention them together in the same sentence as though they were somehow equivalent.

Large wind cost about $1.8 per watt to install and will produce power (in appropriate locations) for about 9-10 hours a day. Solar PV cost about $5-6/watt to install and will produce power for about 5-6 hours a day.

A modest US home uses an average continuous power of about 2000 watts. Using wind, this will cost about $10,000. Using solar, this will cost around $50,000.


Plus the wind equipment is more reliable since it directly drives a generator, whereas the solar PV produces DC power which must be inverted to tie into our electric grid.

Solar PV has its competitive advantage powering off-grid loads, such as remote cabins or school crossing signs.

The point of this post is to try to prevent the baby from being tossed out with the bath water. Wind is viable and might get a black eye if it is too closely associated with Solar PV which is non-viable.

Solar Humor

How many tax payers does it take to install a solar panel?

Ten, 1 to install it and 9 of us to pay for it.

Sadly, the combined utility rebates, federal and state credits, and net meter subsidies make this about right.

Electric Cars and CO2

Some say that electric cars will produce as much or more CO2 as gas cars, but I doubt this is true.

It is true that much of the electricity used to charge electric cars will come from burning fossil fuels, but not all. Here is how we made electricity in 2009 in the US:

Coal: 46%
Gas: 24%
Nuclear: 20%
Hydro: 7%
Renewable: 3%

It will depend on what part of the country you live. The worst scenario might be it you lived were they burn mostly coal, such as my town, Tucson, Arizona. Here, my electric vehicle batteries would be charged from a coal burning power plant. But there are offsetting factors. First, the efficiency of a car engine is about 25%, were a coal power plant is about 40%. But storing energy in batteries means a storage loss of about 20% thus requiring more coal to be burned. But I think the most dominate effect will be the naturally higher overall efficiency of transportation for electric vehicles. Electric cars should be lighter, smaller, slower, and will probably all have regenerative braking so the effective "MPG" might be quite high. Also, because of the speed and range limits of electric vehicles, I think most drivers will drive smarter by combining trips and simply driving less.

If the electric vehicle drove the same speed and range as a gas auto, the CO2 output would be more level, but I don't think this will be the case.

So at the end of the day, I think electric vehicles in regions were power is from nuclear, hydro, or renewables will result in much less CO2 output, and even in areas were coal is burned, I think total CO2 output will be reduced as well.

Commuter Electric Vehicle

In my post titled "Triage" I explained why I thought we should focus efforts on reducing our dependence on oil. Here is a way to take a big step in that direction.

Create a CEV class of electric vehicle (Commuter Electric Vehicle) which:

1) Has a maximum speed of 45 mph,
2) Can be driven using a restricted driver's license,
3) Does not require mandatory liability insurance, and
4) Has reduced safety feature requirements.

We should consider letting people that have lost their licenses drive these cars, mainly because at the reduced speed and weight, they are not nearly the road hazard as typical heavier and faster US cars.

This would be an ideal car for many young people. I like the idea that my kids are in cars which only go up to 45 mph and have limited range.  Using lead acid batteries, these vehicle should cost less than $10K.

Given this new vehicle class, these vehicles would fly off the sales lots, and this would make measurable progress towards reducing our dependence on oil.  Notice that this policy requires no direct subsidies, but encourages EVs by removing government administrative restrictions which apply to our current cars.

The Energy Opportunity Cost of Non-Energy Inputs

This is a tough concept to grasp, but very important in understanding the economics of renewable energy. Many in the PV industry like to claim that the energy payback of the PV panel is quick, but this is misleading since the value of the energy opportunity costs of the non-energy inputs is ignored. Let me try to explain. I hope you can take the time to understand this concept, I had to hear it a few times before it sank in to my thinking.

The non-energy inputs required to make a solar panel can include; aluminium (frame), glass, copper, labor, and capital. But all of these non-energy inputs could be used to make or save energy in other ways. The aluminum in the frames could be used to make vehicles lighter and save fuel. The labor making the panel could be used to change an air filter in a car or air up its tires, or add insulation to a house. The copper could be used to increase the efficiency of an electric motor or reduce the electrical losses in a transmission line.

When non-energy inputs such as labor, materials, capital, and land are used to make PV panels, they are no longer available to be used to save energy in other ways and their opportunity to make or save energy is lost. This is the energy opportunity cost of non-energy inputs.

The next logical question is "how can all the inputs be used in a more energy optimal way?" Should we use the copper in an electric motor or in wiring? An engineer might be tempted to calculate the marginal efficiency gain in the motor or in the wire and determine which is more optimal, and she might be correct. But maybe the analysis forgot to consider copper's use as a conductor in a heat exchanger to improve the efficiency of a refrigeration system, or even copper's use as a decorative object? How is this trade-off made? The answer is surprisingly simple; who will pay the most for the copper? This determines its optimal use.

So how does this apply to solar panels? If the sum of the costs of the inputs to make a solar panel are less than the value of the power it produces, a market should develop for producing solar panels. But what if the return is negative, which is the case with PV panels without any subsidies? Then the numbers tell us the labor, copper, aluminum, glass, energy, capital, and other resources used to make the panel could have/should have been used to save or make more energy had they been allocated to other activities, like making compact fluorescent light bulbs, or wind machines.

The other result of this logic can be the most disturbing, that is we will deplete our resources of oil and put more CO2 in the air faster by making panels than if we did not. Or even worse, given the negative net present value of PV systems not including the cost of the panels, we would be better off having made the panels to simply take them directly to a land fill rather than using the additional resources to actually connect them to the grid.

Pricing Policy

Energy Payback

Several studies have be done to calculate the embodied energy in a PV panel and to then demonstrate that the energy investment is paid back in a short period of time; 1-4 years is commonly claimed. But this does not ring true in light of the very poor economic return. As discussed in "PV Economics", the price of installed grid-tied PV systems need to fall almost by a factor of 10 to make them truly competitive with fossil fuels. These papers use a bottoms up analysis which traditionally underestimated total energy inputs, and they are written by people that are strong solar advocates. Such bottoms up analysis are extremely difficult to make complete.

One reliable way to know the real energy content is to observe the change in price of the panel as energy prices change. If energy cost increased 10% and the panels increased 2%, then we could say the embodied energy is 20% of the total cost. This method automatically captures 100% of the embodied energy cost. Of course, asking all other variable to stay constant during the test is a tall order.

Zero Carbon Footprint

The best way to reduce your carbon footprint is to reduce your spending. China is building a lot of coal plants.

Live frugally!