New Era for Renewable Energy in Japan

Finally, Japan approves incentives for renewable energy.  It took more than a year after the Fukoshima nuclear disaster for the renewable energy industry to get clarity about incentives.  The industry is likely to takeoff in the near future.  The following new incentives ( are in place:

  • 42 yen (0.53 USD) per kWh for solar of less than 10kW, and tariff is for 10 years
  • 40 yen (0.50 USD) per kWh for solar of size 10kW or higher, and tariff is for 20 years
  • 57.75 yen (0.73 USD) per kWh for wind for projects below 20KW, and tariff is for 20 years
  • 23.1 yen (0.29 USD) per kWh for wind for projects above 20KW, and tariff is for 20 years


These are very generous feed-in tariff (very very generous for small wind), which are likely to be updated in March 2013. However, the utility is required to provide guaranteed access to grid for 3 years. What happens after 3 years is anybody's guess.

The government expects capacity of wind to increase by 500MW by end of March 2013.  This will happen only if the pipeline of shovel ready (completed WRA and financing lined up) wind projects is at least 500MW.  Since the Japanese wind industry was on ice for so long, pipeline may be dry; for instance on June 2011, the pipeline of wind projects was 175MW.  If the grid access issue is resolved, we may see 5 to 10GW of wind in four years.

As of December 2011, Japan has 2.5GW of wind installations.  



Feed-in Tariff: Computing and Comparing

At the QLW workshop at ADB in Manila, there was lot of discussion about Feed-in tariff and what is a fair level of FiT. While the debate rages on, this blog will focus on two aspects of FiT: analytical aspect and qualitative aspect. In my presentation at the Clean Energy Forum, I spoke about the problems of comparing FiT of two countries. I described as an apples-to-oranges comparison, and what really needs to be compared in the entire fruit basket of tariffs and incentives that make up the total package for financial analysis.

Lets start with definition of Feed-in Tariff. FiT started in late 70s in the US, where renewable energy prices were set based on the cost of generation. Two other key provisions were guaranteed grid access and long-term contract. Let us focus on the pricing mechanism of FiT, which is cost of generation. Cost of generation is computed to ensure that a generator makes a reasonable return on investment, while operating the generation plant efficiently. The FiT computation therefore is based on:

  • Technology (wind, solar, bio-mass)
  • Quality of resource in a geographical area
  • Financing structure: % debt, duration of debt, interest rate, rate of return on equity
  • Capex cost, which depends on: Delivered cost of equipment and balance of plant Opex cost, which depends on cost of O&M
  • Incentives offered: Investment-based, generation-based and others

As one would imagine, this gets complicated and political. Complicated because there are lot of factors involved like quality of resource, certainty of resource, length of transmission line, interest rate, currency, etc. Judgments have to be made, often, without adequate studies. Political because the generation industry wants to get a higher tariff and consumer groups want to ensure that the tariff is low.

Land Use by Wind Energy Projects

I am often asked by prospects interested in wind projects about amount of land required by a wind project.

There are two questions:  

  1. How many MW of wind capacity may be put in 1 SqKm (or 247 acres) of land?
  2. What is area of land that is made unuseable by a wind project?  Meaning how much land is used up by foundation of turbine, roads, substations, storage area, admin offices, etc.?  By implication rest of the land is available for agriculture, grazing or other similar purposes.


The correct answer is, detailed micrositing is required in order to accurately determine the land requirements.  However, there are several rules of thumb that are employed by practioners to compute a reasonable estimate.

Answer to question 1:  About 7.5MW/Sq.Km., or 1/7.5 Sq.Km. per MW or about 33 acres per MW in flat areas.

How is this number computed?  Let us do simple back-of-the-envelop calculations.  Assume, turbines are separated 3Dx9D, where D is the rotor diameter; in the primary direction of wind the separation is 9D and in the perpendicular direction the separation is 3D.  Consider 125MW wind farm consisting of fifty 2.5MW turbines with D=100m, and the 50 turbines arranged in 5 rows.  In this idealistic case, wind farm will take up 0.3*10*0.9*5=13.5 Sq.Km; that is, 9.25MW per Sq.Km. in an ideal case.  This assumed a perfect array of turbines, which may be a good layout for offshore, but land is never perfect.  So, applying a 20% increase in land results in 7.7 MW per Sq.Km.

Important considerations:

  • Terrain:  In hilly terrain, acceptable spots for turbines are limited to ridge lines. Therefore, the land required may jump to 60 acres per MW or higher if considering a square plot of land, because valleys and shadow of mountains are not useable by wind turbines.

  • Wildlife areas and protected forests

  • Residential/industrial neighbors 

  • Public utilities: roads, transmission, microwave, aviation airspace

  • Others: Primary direction of wind, 3Dx9D and capacity of turbine.  Depending on the seasonal wind rose, 3Dx9D may become 5Dx9D.  As the calculation above indicate changes in turbine separation, turbine capacity and other parameters will change the land requirement.

Answer to question 2: About 3/1000 Sq.Km. per MW.  That is, if 0.1334 Sq.Km. of land is required per MW, only 0.003 Sq.Km. per MW  will be used by physical assets of the wind farm.   That is, about 2.5% to 3% of land is directly occupied by the wind farm for foundation, roads, etc.; rest of the 97% of land can be used for its original purpose.

Important considerations: 

  • Size of wind farm; the numbers above are for larger wind farm (>50MW)

Myths about Impact of Wind Turbine Generated Infrasound and Low-frequency Sound on Health

I was at a wind energy workshop speaking about noise issues.  There I was asked several questions about low-frequency and infra- sound and its impact on health.  Because of the questions at the workshop, I decided to write this note.  

In this blog, I will highlight what is known about infrasound and low-frequency sound issues and the conclusions of an expert panel of physicians, otolaryngologist, and physicists with expertise in noise, vibrations and safety.  The panel was organized by the American Wind Energy Association (AWEA) and Canadian Wind Energy Association (CANWEA).  Let us start with the conclusions:
“1. Sound from wind turbines does not pose a risk of hearing loss or any other adverse health effect in humans.
2. Subaudible, low frequency sound and infrasound from wind turbines do not present a risk to human health.
3. Some people may be annoyed at the presence of sound from wind turbines. Annoyance is not a pathological entity.
4. A major cause of concern about wind turbine sound is its fluctuating nature. Some may find this sound annoying, a reaction that depends primarily on personal characteristics as opposed to the intensity of the sound level.”
The conclusions clearly state that the sounds generated by wind turbines are not harmful to human health. Next, let us dig deeper.

What is low frequency and infra sound?

Low frequency is sound with a frequency range of 10Hz to 200Hz.  Infrasound corresponds to frequency below 20 Hz, the lower limit of audible frequency at normal sound amplitude.  Note at sufficiently high volume (amplitude) infrasound is audible; therefore the exact frequency that defines infrasound is not precise.

Why focus on low frequency and infra sound?

The speed of sound in air is about 340 m/s.  The product of frequency and wavelength is equal to the speed of sound.  For example, if frequency is 20 Hz, then the wavelength is 17m, which is large.  As it turns out most of the common noise (due to traffic, airports) inside a house is low frequency because walls and other barriers easily block higher frequency noise.  This low frequency noise can be annoying if the noise level is high, as measured by dBA.  
At 20 Hz, a noise level of 80 dBA is barely audible.  At lower frequencies, the noise level has to be even higher for it to be audible.  As a result, in almost all situations in which the turbine is outside a radius of 150m from a residence, the low frequency sound is barely audible because the noise level in terms of dBA is in the range of 50 to 60 dBA.  At such low noise level, the sound may be annoying, but has no impact on health.