2010-12-30 15:59:18What is the Potential of Wind Power?
perseus

owlsmoor@googlemail...
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NOTE FROM JOHN COOK: This is an invited guest post by Steve Latham (username perseus) who I've just invited to the Authors Forum. He sent me this article on wind power which I thought we could use as a blog post but also adapted into a rebuttal of one (or more) skeptic arguments on wind power (although I'll need to scratch around for examples of skeptic articles on wind power - suggested links welcome). I thought it was a strong article but perhaps might need have a few acronyms or concepts difficult for someone new to wind power and renewable energy. So feedback on this blog post is welcome:


What is the Potential of Wind Power?

by Steve Latham

Could wind make a significant contribution to our energy requirements?

Global wind power has doubled over the last 3 years, which now accounts for 2% of the world’s electricity production, and as much as 20% in some countries. It is estimated that 13% of the worlds land area has wind speeds greater than 6.9 m/s at commercial wind turbine heights, this could theoretically produce 40 times the world's current electricity production.  Although the total quantity of wind energy potentially available is considerable, there remain obstacles to the substantial expansion of this industry.

Critics claim that wind power cannot replace conventional power sources since these still need to be available for when the wind isn’t blowing, and these are expensive to keep in reserve and waiting on part load, reducing overall energy efficiency. For low contributions, wind power can be considered largely additional, since reserves are always needed to cater for unexpected unavailability of the largest single power source and having a large number of smaller generating units can sometimes be beneficial.

In addition to providing replacement power, wind plants reduce emissions by forcing the most polluting and inflexible power plants offline with more efficient and flexible types of generation.  However, with increasing use of wind energy in the system the proportion of conventional plant wind replaces reduces, and consistent wind power generation requires high voltage connections to wind farms over a wide area.

Further expansion of the industry may also require energy storage technologies to balance fluctuations of supply and demand; these include hydroelectricity, compressed air storage and electro-chemical batteries. The latter option is particularly interesting in view of the potential use of battery-electric vehicles in the future since their batteries could be charged overnight when power demand is low and used to supply power during peak demand periods. Peak electricity demand could also be reduced through pricing structures and switching off non-essential appliances.  

In addition to to replacing carbon intensive electricity production, wind power can drive heat pumps for space heating or charge vehicle batteries for transport, reducing natural gas and petroleum use. These are more efficient methods of producing heat and work than the traditional methods they replace, so direct comparisons of energy cannot usually be made . For example, one popular book grossly underestimated the potential contribution of wind power, partly because it compared the electricity generated from wind turbines with the primary chemical energy in fossil fuel directly.

This same book also concluded that heat pumps are a more efficient method of supplying energy than combined heat and power systems.  However, I suggest that both systems could be used together to provide even greater benefits, and provide a means of matching wind supply with demand, thereby increasing the proportion of wind power used.

Figure 1 below illustrates a potential combined heat and power scheme where the energy input to a heat pump could be switched between electricity, partly powered from wind if necessary; and a directly coupled natural gas or biogas powered internal combustion engine. The engine can also drive the generator directly, providing backup power if necessary.  I believe that by using energy in a strategic manner like this, wind power and other intermittent renewables can be more fully utilised within the grid system

Figure 1: Strategic local CHP and mains Operated heat pump system  to expand the use of centralised renewable electricity

 Is wind power more expensive than conventional energy sources?

The relative price of wind relative to fossil fuel based power is dependent upon a large number of variables making comparisons difficult and sometimes controversial. However, one of the most important is the price of fossil fuels, particularly oil and gas which could substantially increase in the future as cheap supplies become depleted.

Onshore wind appears relatively competitive with current (late 2010) oil prices at 88 $/barrel (see figure 2 below). To compete at lower oil prices or much higher wind penetration rates, the external costs of fossil fuels need to be included such as the effects of future global climate change, local pollution, and sometimes hidden subsidies and military expenditure to secure supplies.  When the cost of fossil fuel electricity using carbon capture, and nuclear power are compared with wind on these terms, even offshore wind schemes appear competitive. However, there are large uncertainties in the cost of deep-sea wind turbines, modern nuclear and in particular carbon capture technology, which has still to be proven on a large scale.

Figure 2: Oil price at which various generating technologies become competitive   

(Lower bar subsidised, upper bar unsubsidised)

Other Issues with Wind Power

There is sometimes substantial local opposition to the installation of large wind turbines, despite assurances that they are unlikely to adversely affect wildlife or human health. One method of mitigating these problems is by providing communities with a commercial stake in the wind farm, creating local jobs and collecting revenues by exporting electricity to the grid.

In practice, governments often prefer a variety of energy sources to improve security of supply and avoid reliance on any one region.  Therefore, it can be politically and economically beneficial to include indigenous wind sources as part of the overall national energy strategy.

Conclusion

Wind power could economically provide a significant proportion of electric power for many countries and contribute usefully to their transportation and space heating requirements. One example is shown here for the UK. However, different countries will need to use different combinations of renewable and zero/low carbon technologies depending upon the local climate and resources.  To fully exploit this, a strategically managed, widely spaced grid network needs to be developed, which should ideally be linked to offshore wind and other low carbon technologies.

2010-12-30 17:39:56
Rob Painting
Rob
paintingskeri@vodafone.co...
118.93.205.205
Reads very well to me, and it's an area in which I haven't much background knowledge. Figure 2. is very informative, but isn't intuitively that quick to grasp, but maybe that's just me. Great job. 
2010-12-31 05:13:12
MarkR
Mark Richardson
m.t.richardson2@gmail...
78.149.138.98

My concern about some of these articles is that they don't deal with some of the biggest problems with wind...

 

 

Price analyses rarely include grid balancing costs and relevant effects on CO2 emissions. Gas might be cheaper, but spinning reserve and changing output quickly is bad for efficiency for example. I think this should be included more obviously. 

2010-12-31 05:13:59
MarkR
Mark Richardson
m.t.richardson2@gmail...
78.149.138.98
Generally, this reads like a pro-wind propaganda piece like I've read on loads of other sites. It isn't the sort of incisive scientific commentary I associate with most of SkS output...
2010-12-31 21:15:28
perseus

owlsmoor@googlemail...
78.143.201.89

MarkR

It is notoriously difficult to obtain reliable costs, since this depends upon so many factors.  I am fully aware of the issues of balancing etc and have briefly mentioned these.  In fact I have gone into a great deal of detail how this problem could be mitigated by integrating electric generation with space heating via using local CHP generating stations and heat pumps.  

I am also cynical of claims from the wind (and nuclear) industries, since my background Engineering. Whilst researching this I received this reply from someone in the wind industry which I have obviously ignored

OK I've done some maths. Onshore wind costs about 3.5p/kWh and offshore wind costs about 5.8p/kWh.  What I have done is take the capital cost of the wind farm, then take the present value of 20 years of operational costs. Then looked at the expected generation over 20 years and that's the figure I come to above.

My reply:  Thanks ...... That sounds very cheap. However, presumably it doesn't allow for the fraction of conventional plants which need to remain on line but not generating. I thought that was a major portion of the real cost, which is why energy generators think the real cost of wind turbines are much higher?

Any reputable cost calculation should include these factors, but must vary considerably depending upon the situation and extent of the wind network.  After reviewing a number of costs ranging from pro-nuclear to pro-wind sources the one in the article appeared middle of the road in relative terms, but I can't guarantee its applicability to everywhere. 

Perhaps the presentation of the cost in terms of oil needs clarifying?  although the relative cost is more important, but I will look into this and re-check some absolute figures at the same time.

PS  The source of these cost estimates originates from Cambridge Energy Research Associates CERA. 

Cambridge Energy Research Associates, also known as CERA, is a consulting company that specializes in advising governments and private companies on energy markets, geopolitics, industry trends, and strategy. CERA has research and consulting staff across the globe and covers the oil, gas, power, and coal markets worldwide
2011-01-07 02:09:28
perseus

owlsmoor@googlemail...
78.143.200.120

 

I have linked some further notes on wind power costs here including a few recent sources of information.

The IEA & Nuclear OECD nuclear energy agency provide detailed costs for different energy sources and discount rates, but I am unsure how much we can rely on their nuclear estimates.  However, their wind power estimates still appear competitive with coal and gas outside Europe.  Perhaps the most up to date figures are published from Mott McDonald who believe that recent increases in fuel costs have made wind energy more competitive, although these may only be applicable to the UK.  

After converting to Dollars/MWh their cost estimates are

Nuclear = 150   9% more than on-shore wind
Coal = 158
       15% more than on-shore wind
Closed cycle gas turbine = 124
   10% less than on-shore wind
On-shore-wind 137

Off-shore-wind = 231  69% more than on-shore wind

these relative differences are not far off those
 in figure 2 which I will rename for clarity.

There is also a link to a detailed study on intermittency costs which don't appear too severe

I will also try to tone down some of the statements and mention some of the other economic factors affecting competitiveness.