permaculture

["Lawrence F. London, Jr." <lfl@intrex.net>]

-------- Original Message --------
Subject:        [SANET-MG] wind power
Date:   Tue, 12 Jul 2005 11:44:58 -0400
From:   jcummins <jcummins@UWO.CA>

        

        

http://www.i-sis.org.uk/TTTW.phpISIS Press Release 12/07/05

Taking to the Wind
Peter Bunyard looks at the realities of wind power and answers its 
detractors

Peter Bunyard will be speaking at Sustainable World Conference, 14-15 
July 2005.

References for this article are posted on ISIS members’ website. Details 
here

Wind power working
Ian Fells, professor of Energy Conversion at Newcastle University, told 
BBC’s Radio 4 Today programme back in December 2002 that if we wanted 
electricity on tap, while simultaneously meeting our Kyoto Protocol 
commitments to reduce carbon dioxide emissions, we would fail abysmally 
unless we replaced and even added to our nuclear power capacity (25 per 
cent of UK electricity generation in 2005). Renewable energy sources, 
such as wind-power, he insisted, would be marginal to needs and barely 
worth the cost of developing [1].

Ian Fells’ remarks contrasted with the experience of one of Denmark’s 
energy experts who, during the same December 2002 Radio 4 programme, 
pointed out how successful his country’s strategy had been in developing 
an electricity supply industry (in which wind-power provides nearly 20 
per cent of the total in 2005). It had been good for jobs, good for 
exports and good for Denmark’s energy needs, with the industry employing 
16 000 and annual sales of wind turbines reaching more than 2 GW, equal 
to two large nuclear power plants.

Peter Edwards, ex-chairman of the British Wind Energy Society developed 
the first British wind-farm at Delabole in Cornwall 14 years ago in 
response to the threat of a nuclear power station being built nearby. 
Initially the economics did not look good, at least in the context of 
the UK, and Edwards all but abandoned the idea. But then, in 1991, the 
government simultaneously introduced the fossil fuel levy on fossil fuel 
generating plants and the non-fossil fuel obligation (NFFO) to support 
at least 20 per cent electricity production from non-fossil fuel sources.

At the time, nuclear power was generating 20 per cent of the Central 
Electricity Generating Board’s production, and with privatisation in the 
offing, the NFFO was little more than a straight subsidy to sweeten up 
the City in time for a sale. Nonetheless, the subsidy did open up the 
possibility of investing in the alternatives, such as wind. In 1990, the 
fossil fuel levy amounted to £900 million, much of which went into the 
pockets of the nuclear industry.

As Edwards told me in 2001, ten years on from establishing his 
ten-turbine wind-farm, performance has been better than predicted. “We 
now have 10 years of records carefully analysed by ETSU (Energy 
Technology Study Unit) at Harwell, as well as by the DTI, and have 
discovered benefits from wind generation that we barely suspected. 
People are quick to say that the wind is fickle and that it fails just 
when you most need it, but such critics have also failed to understand 
that when we most need the energy, that’s when the wind blows. In our 
part of the UK, 60 percent of annual generation is between October and 
March. Consequently, wind generation and demand go together; in winter 
when the wind blows, the chill factor goes up and so does the need for 
electricity; in summer just when everyone is returning home for their 
tea in the early evening that’s when the onshore winds obligingly come 
into play.”

It took just a few months to get the Vesta 400 kilowatt turbines up and 
running. Moreover, each of the machines had been sited in hedgerows 
across the farm, with minimal loss of land, and since they were all 
plugged into the local Delabole 11 000 volt substation, they instantly 
provided power to the neighbourhood and hence avoided the substantial 
distribution losses that go with distantly connected power stations.

“Such embedded generation immediately improves the quality of supply,” 
Peter Edwards said, “evening out those fluctuations that have been a 
curse of electricity supply throughout Cornwall, not least because the 
bulk of our electricity comes from the Hinkley Point nuclear power 
station, more than 150 miles away. It’s rather like a blood transfusion 
into an extremity where bleeding is occurring: you balance out the loss 
and consequently the local voltage is now much more stable. Cornwall now 
has six wind-farms, enough to supply some 27 000 households, and whether 
locals know it or not, the quality of their electricity has gone up 
substantially.”

In much of Western Europe, wind-power has really taken off, for instance 
in Germany, Spain, Denmark [2]. In Britain, largely because of the cost 
of planning applications and public resistance, development has been 
slower. However, by the beginning of 2003, the UK had a total of 552 
megawatts of installed capacity in place from 78 different projects and 
another 17 to be constructed over the coming two years. By January 2005, 
another 340 MW of wind farms were up and running, hence the equivalent 
in capacity terms of a small nuclear power plant, all constructed within 
a matter of months of the work commencing. Some of the new wind farms 
involve relatively large machines of 2 and 2.5 MW, and several are 
offshore. Britain intends to have 20 per cent of its electricity 
generated from renewable sources by 2020, Denmark intends to go a good 
step further with 50 per cent being provided from such sources [3].

The detractors
Wind as a source of energy for generating electricity has many 
detractors. The arguments range from “unsightliness and a blot on the 
landscape”, to noisiness and perhaps the most damming of all, to its 
ineffectiveness and inefficiency, particularly the intermittent and 
unpredictable nature of the wind. Here again, some myths need 
dispelling; first, that they are inefficient as measured by the 
percentage of electricity generated compared to the size and capacity of 
the wind turbine. Basically, critics refer to the 30 per cent or so of 
production compared to capacity. They neglect that the capacity of a 
nuclear power station tends to be measured in electricity capacity (MWe) 
rather than in the thermal units required to generate that electricity 
which can be more three times greater.

Godfrey Boyle of the Energy Environment Research Unit at the Open 
University points out in a personal email to me (March 2005) that the 
size of turbines has been increasing spectacularly in recent years and 
the largest machines in operation today can have a capacity as high as 
4.5 MW. Most of the machines now being built in Britain, whether onshore 
or offshore, are rated at about 2 MW.

How much land would be required were such wind-machines to provide 20 
per cent of UK requirements? In 2003, total UK electricity was a little 
short of 400 TWh (terawatt hours=1012 watt-hours) so 20 per cent would 
amount to 80 TWh. Denmark, which manufactures many of the turbines used 
here and has considerable experience of siting such machines, suggests 
that each individual turbine should have a downwind spacing of 7 to 9 
diameters and a crosswind spacing of 3 to 5 diameters, with resultant 
array losses of around 5 per cent.

Therefore, each turbine of 2 MW at best would require a minimal area of 
16.5 hectares, although it must be appreciated that the land is still 
open and can be used for recreational and agricultural purposes right up 
to the turbine tower. Including array losses of 5 per cent, the average 
annual output per turbine would be 5 GWh (gigawatt hours=109 watt-hours) 
and the output per hectare of 300 MWh/ha. To produce 80 TWh would 
therefore require 267 000 hectares, which is just over 1 per cent of the 
total UK land area [4].

In principle, the UK could meet up to 20 per cent of its current 
electricity needs from the use of land-based wind-turbines. Add to that 
offshore wind-turbines and the proportion could go up significantly and 
certainly surpass nuclear power’s current contribution of 25 per cent of 
all electricity generated in the UK.

Critics of wind power in particular and the renewables in general make 
much of their intermittency; the fact that they do not deliver a steady 
source of electricity hour by hour throughout the year. In a 
conventional electricity supply system attached to a central grid, the 
notion is to have base load electricity generated by plants that do best 
as steady work horses, such as coal-fired plants or indeed nuclear 
power. In fact, the economics of nuclear power stations demands that the 
high up-front construction costs are mitigated by constant operation 
with an optimum power output. Spurts in demand, or peak loads, add to 
the generating requirements and need to be met with other power plants, 
such as hydro- or gas turbines, which can be brought on stream rapidly 
and shut down equally rapidly. Response to such spurts in demand, or to 
unexpected breakdowns, is met by keeping some power plants in the 
electricity supply system as ‘spinning’ reserve whereby the turbines are 
kept rotating, even when their power output is not required. To meet 
peak demand is inevitably more expensive in terms of unit costs and 
therefore in relative greenhouse gas emissions, than providing for a 
steady base-load.

The renewables, such as wind, do not fit neatly into the category of 
providing base-load electricity nor can they be brought on at will to 
supply peak demand. As the engineer Andrew Ferguson points out [5]: 
“There is no way that we can order wind turbines to follow demand,”  and 
on the basis that the wind supplies 30 per cent of the ‘block’ of 
electricity determined by the peak demand, and the flexible back-up 
system provides 70 per cent then, according to Ferguson, the 70 per cent 
is likely to be supplied inefficiently at 35 per cent because of 
operating ‘in harness’ instead of 60 per cent as can be obtained in a 
combined cycle gas turbine (CCGT).

“Hence, the gas needed will be 0.70/0.35 = 2 units, whereas were there 
to be no wind turbines, 100 per cent of electricity would be supplied by 
CCGTs operating efficiently (60 per cent), and the gas needed would be 
1/0.60 = 1.67 units.  Thus using wind turbines increases gas consumption 
by (2/1.67) -1 = 20 per cent.”

Ferguson’s pessimistic view is not held by others in the industry. Lewis 
Dale, a member of the DTI/Ofgem Technical Steering Group, together with 
David Milborrow, Richard Slark and Goran Strbac, all professionals in 
the field, have looked at the costs for introducing different 
proportions of wind power into the generating system [6]. They take into 
account the impact of wind on the need to establish and maintain other 
generating capacity; and network costs, which arise through reconciling 
the input from wind with the other inputs into the grid.

They then compare two scenarios for the year 2020 in which electricity 
demand has increased by 17 per cent with total electricity sales of 400 
terawatt-hours and a peak demand of 70 GW. In the first scenario 
electricity is provided through using coal and gas, with progressive 
improvements in efficiency, and ever-greater incursions of combined heat 
and power. In the second scenario wind power has increased to the extent 
of providing 20 per cent of electricity sales derived from 26 GW of 
capacity with an average 35 percent load factor (a measure of efficiency 
given by the ratio of energy produced during a given period of time over 
the energy that would have been produced had the wind farm been running 
continually at maximum output) and a typical wind speed of 8.3 metres 
per second. For the sake of the analysis 60 per cent of the wind 
capacity is located offshore, connected directly to the central grid and 
the remainder is located onshore, connected to the 132 kV distribution 
network or even lower.

In effect, if 26 GW of wind power with a 35 per cent load factor were 
installed, some 5 GW of conventional capacity would no longer be needed, 
given that replacement electricity has to be generated to make for 
shortfalls as a result of intermittency. The authors do not deny that, 
“technical costs arise as reserve plant is part-loaded and, in 
consequence operates at lower efficiency...”

Most importantly for 20 per cent of the generating mix coming from wind 
energy, some 19 per cent of fossil fuel combustion is avoided. That 
includes a 1 per cent reduction in the savings because of using less 
efficient generators as part of the reserve. That conclusion presents a 
markedly different picture from the pessimistic one of Andrew Ferguson.

           In general, the economics of wind power are based on the 
amount of fuel saved plus the amount of generating capacity not required 
minus the costs associated with intermittency. As the Carbon Trust and 
the Department of Trade and Industry conclude in a recent report: “10 
per cent wind penetration would displace about 3 300 MW of capacity and 
20 per cent about 5 000 MW. As far as generating costs the additional 
balancing costs would add between 1.6 and 2.4p per kilowatt-hour for 10 
percent penetration and between 1.9 and 2.8p for 20 percent.”

Timur Gül and Till Stenzel, reporting for the International Energy 
Agency, conclude that windpower as well as other renewable energy 
sources, including photovoltaics, backed up by electricity generation 
from biomass, will make a good contribution to overall electricity 
supply. [9]

Ferguson, like the Carbon Trust/DTI, is hooked into a conventional way 
to supply and distribute electricity that entails a central grid system 
supplied by large thermal power plants, whether fossil-fuel fired or 
nuclear. But, what about an innovative look at an electricity supply 
system that does rely considerably on renewable sources, whether 
intermittent or not, and yet is energy-conserving and therefore efficient?

Embedded local power supply for maximum efficiency
To start let us look back to what is happening in France where the bulk 
of electricity comes from nuclear power plants (“Deconstructing nuclear 
power myths”, this series). The French consumer prefers to use natural 
gas for central heating, cooking and heating water, thus making heavy 
inroads into the supply of electricity from nuclear power, in much the 
same way that Ferguson has indicated happens with the intermittent 
supply from wind turbines. The difference is that the gas heating system 
switches on with demand rather than being prey to the wind, as is the 
case with wind turbines, while simultaneously being an efficient 
producer of end-use energy.

Judiciously sited in a housing complex or block of flats, the overall 
efficiencies of gas-fired combined heat and power systems, which provide 
useful heat and electricity, can amount to nearly 90 per cent. If biogas 
is used then the net carbon emissions are extremely low (and much better 
than using current nuclear power), moreover the system can be powered 
down when the wind is blowing strong and brought up to full power when 
needed.

With such a system, the wind would make a substantial difference to the 
amount of fuel required, simply because of the embedded nature of the 
flexible power supply system. That is not to say that the central grid 
should be dismantled but, acting in the manner of a back-up system for 
local embedded power production.

If so, at one stroke, the UK could reduce demand for electricity by 25 
per cent or more, simply by balancing out the difference between base 
load and peak load requirements. Systems that do just that have been in 
operation for at least 30 years and were part and parcel of small-scale 
generating systems used in isolated dwellings and communities. The 
inspiration for such a system came from a West-country based engineer, 
Rupert Armstrong-Evans, who wanted to extract as much power from a 
system, such as mini-hydro plant, that it could possibly deliver [7].

Even though the electricity fluctuated on a daily or hourly basis, it 
could be manipulated electronically to provide superb quality power for 
delicate appliances such as computers, TVs, and the like. A black box 
between the end-use consumer and the supply took any excess power, over 
and above that being used for lights and appliances, and dumped it in a 
buffer heating circuit. Hence storage heaters, immersion coils in 
boilers and even storage heater cooking stoves benefited whenever excess 
electricity was available, such as during the night when the household 
was asleep, or indeed during the day if the occupants were out working.

Clearly, in such a localised embedded system, there are limits to the 
amount of electricity that can be provided at any one moment. 
Armstrong-Evans therefore devised his black box to warn the household 
that it was approaching the limits when demand for quality electricity 
was near to exceeding supply. Then all that the consumer had to do was 
to switch off some appliance that could be dispensed with, at least at 
that moment. In effect, the consumer was made responsible for judicious 
and constrained use of electricity without losing the comforts and 
conveniences of the modern home.

Imagine the use of such black boxes throughout the UK: they could be set 
to allow in a fixed amount of electrical capacity. When the household 
was asleep and using minimal appliance power, the electricity entering 
the building would pass automatically through to heating circuits, 
possibly including heat-storage cookers. In effect each household would 
have its base-load requirements that could be regulated from month to 
month, season to season. Were the demand to go above the set amount, 
then the consumer would pay heavily for the marginal costs of bringing 
in more electricity. It would then be up to the consumer to limit the 
intake into the household by switching items on and off as required, 
rather than leaving them on without regard for the impact on the total 
generating capacity required.

Once the levels of electricity supplied by an intermittent source, such 
as from wind turbines, fell below a critical point, then the back up 
Combined Heat & Power system would automatically come on stream, 
levelling off the power produced as the wind came back and then 
switching off were the wind to be back in full strength. The management 
of such a system could be left to electronic controls combined with 
self-responsibility.

Just by leaving appliances on stand-by in the home, gadgets such as TVs, 
washing machines, dish-washers, DVD players as well lights, we in the UK 
are responsible for emitting an extra one million tonnes of carbon-based 
greenhouse gas into the atmosphere  [8]. That is enough energy, says 
DEFRA, the Department for Environment, Food and Rural Affairs, which 
commissioned the report, to power the needs of 400 000 homes; and 
turning the appliances off could reduce electricity requirements by the 
equivalent to at least one large-sized generation plant [9].

The UK government is now suggesting that manufacturers should sell 
appliances that automatically switch themselves off when not in use. In 
essence, energy conservation in the home, at work, in factories and in 
transport, is by far the cheapest and most effective way of reducing 
greenhouse gas emissions — certainly an order of magnitude cheaper than 
building a new nuclear power station per kilowatt saved and immeasurably 
safer.

Whatever we do, we must avoid falling into the trap that Tony Blair and 
others are setting for us in making us believe that we have no options 
available to us other than resorting to nuclear power. And we must 
certainly give the lie to the notion that nuclear power is greenhouse 
gas emission free or indeed can provide us with bounteous energy for as 
long as we can see into the future. Renewable energy sources are there 
for the taking and we must learn to use them efficiently and wisely. It 
is time to take the wind out of nuclear power.



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