Bjorn Lomborg on German solar subsidies

February 18, 2012

Bjorn Lomborg (The Skeptical Environmentalist and Cool It) has an interesting article (Goodnight Sunshine) describing the late realization in Germany that their massive investment in solar energy is “a massive money pit” and “a threat to the economy.”   They have subsidized 1.1 million solar photovoltaic installations to the tune of $130 billion, which provide a whopping 0.3% of the nation’s energy.

If you are worried about anthropogenic CO2 induced global warming (a.k.a. climate change, a.k.a. climate disruption), he points out

“This sizeable investment does remarkably little to counter global warming. Even with unrealistically generous assumptions, the unimpressive net effect is that solar power reduces Germany’s CO2 emissions by roughly 8 million metric tons—or about 1 percent – for the next 20 years. To put it another way: By the end of the century, Germany’s $130 billion solar panel subsidies will have postponed temperature increases by 23 hours.”

And as to “green jobs” boosting the economy of Germany…

“[E]ach job created by green-energy policies costs an average of $175,000… And many ‘green jobs’ are being exported to China, meaning that Europeans subsidize Chinese jobs, with no CO2 reductions.”

I have one large quibble with his Lomborg’s numbers.  He says

“Even with the inefficiency of current PV technology, we could meet the entire globe’s energy demand with solar panels by covering 250,000 square kilometers.”

It would really take closer to a million square kilometers.

Why a million square kilometers?

Because even good solar panels (say, rated for 150 Watts/m2) will yield much less than their name plate power for a variety of reasons.

1. A one square meter solar panel in a huge array actually requires a land area of at least 1/cos(latitude) meters.  This is the land area shaded by the one meter panel by the sun at noon.  It is larger at other times of day.

2. Extra area is required for infrastructure, such as service roads

3. The capacity factor for solar energy is about 20%.  This means that if a solar panel’s name plate says that it is 150 watts,  then on the average it will yield about 30 Watts because sometimes it is night, sometimes it is cloudy, and even during a sunny day the incident angle is optimal for only several hours before and after noon.

In Berlin, for example, where the latitude is 52 degrees, a one square meter panel in a huge array will require closer to 1.7 square meters of land.  A typical good quality one square meter panel with a name plate wattage of  150 Watts at peak averages out to about 30 watts over the course of a year because of the 20% capacity factor.  This translates to an average of about 18 Watts per square meter (30 Watts divided by 1.7 meters).

World energy consumption is about  5×1017  BTUs per year (about 1.5×1017 watt-hours/year).  That is an average power consumption of  about 1.7×1013 watts (1.5×1017 watt-hours/year divided by 8760 hours/year)

Therefore, it would take about a million square kilometers of solar arrays (1.7×1013 watts divided by 18 Watts per square meter).

This all assumes that the energy impoverished of the world are happy to stay that way.  Oh well, we all have our crosses to bear.

You can see Lomborg’s complete article here.


  1. In your 23 hr temperature delay you have neglected the temperature rise due to the extra heat contributed by the land use change — e.g., the photovoltaic collectors are darker than the green or brown earth. Please correct.

    • Philip Lee,

      What do you mean by a “23 hour temperature delay?” I made no reference to such a thing.


  2. Maybe I worded it inartfully, but “To put it another way: By the end of the century, Germany’s $130 billion solar panel subsidies will have postponed temperature increases by 23 hours” is a quote from above. Now, how about responding to the intent — i.e., changing land use for solar energy will raise global temperature, won’t it?

    • Sorry Philip,

      I understand your question and point now.

      “Changing land use for solar energy will raise global temperature, won’t it?” is a good question. I don’t know the answer.

      I think it is fair to say that most of the “usable” energy captured by the PV arrays will ultimately be converted to heat. On the other hand, an equal amount of heat would have been released from the fossil fuels that they replaced.

      A large part of the radiation incident on a solar panel is not converted to “usable” energy, and is reflected away, or converted to heat and radiated away as IR, or convected away by the air. (As and aside, the efficiency of PV solar drops dramatically as the temperature of the panel increases.)

      That seems to support the idea that the solar PV might raise global temperature. But I do not know how it would balance out.

      Do you know of anybody who has done calculations or research about this question?


      • I know of no research, but my flesh touching black asphalt in a Mississippi summer compared to grass suggests a local temperature issue — and maybe a global temperature issue big enough with 1 million square km to make up for the 23 hr lag. Maybe another reader will be able to answer.

  3. I agree, but people need to realise that adding Solar in their house is an purchase that could boost the future valuation of their residence if / when they choose to sell. With the environment the way it is going we simply cannot underestimate any item that presents 100 % free energy at no cost to both the client and more importantly the earth!

    • Nadene,

      Solar is hardly “100 % free energy at no cost to both the client and more importantly the earth!”

      No offense, but that is an extraordinarily naive statement. Of all energy sources, renewable or not, solar PV is the most expensive.

      By the way, suppose you wanted to generate enough energy from solar so that each person on the planet could get 40% of what the average American uses. That would take roughly a million square kilometers of land and the cost would be many times the yearly gross economic product of the world.


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