What are small wind turbines mainly used for?

There are two uses for small wind turbines that account for the vast majority of sales. Either for charging batteries or for connecting into the electrical grid. Smaller markets exist for electrical heat or for water pumping.

Historically the battery charging winf turbines have been smaller, and the term micro wind is loosely applied to turbines of less than about 1 kW – although battery charging units of up to 50 kW are not unusual, and battery charge is therefore not synonymous with micro wind.

The grid connect wind turbines have historically been small wind turbines of 6 kW or more, but over the last few years some manufacturers have pushed grid connection technology downmarket, to machines as low as 250 W.

Perception problems for small wind

Contrary to popular opinion, the small wind industry is not an amateurish cottage industry. A listing of the key small wind turbine manufacturers and the approximate numbers of turbines they have made is instructive. The historic leaders are Southwest Windpower (SWWP), which has manufactured over 140,000 wind turbines in a 25-year period; closely followed by Marlec (80,000 wind turbines, 30 years); Ampair (20,000 wind turbines, 35 years); Fortis (6000, 20 years); Bornay (4000 wind turbines, 35 years); Bergey (5800 wind turbines, 30 years); Proven (2500 wind turbines, 25 years); and Eclectic (2000 wind turbines, 5 years).

At the micro wind end of the market the dominant players are SWWP, Marlec, Ampair, and LVM. These four compete globally on a daily basis, selling a boxed product for battery charging that retails in the US$500-1000 range.

A similar situation albeit with lesser volumes exists amongst the leading manufacturers of small wind turbines of 1-15 kW: Proven of the UK, Fortis of the Netherlands, Westwind of Ireland (previously of Australia) and Bergey of the USA. These have been joined in the last five years by well respected turbines from newcomers Eoltec, Kestrel, Endurance, and Evance (previously Iskra) and a resurgent Danish/Scottish company Gaia. Both SWWP and Ampair have also started moving up into this size range.

Larger wind turbines are made by Entegrity and the related AOC design of Canda, and Northern Power Systems with its 100 kW unit.

The highest volume manufacturers amongst these are able to ship thousands of boxed products per year on an unsubsidised commercial basis and support global dealer networks that reach into the farthest corners of almost every country on the planet.

They have been doing this for 25-35 years and have survived whilst dozens – if not hundreds of their competitors – have come and gone. Over the decades the individual product ranges have improved as a result of continuous R&D, respective brand reputations have been built, as have intellectual property portfolios, and manufacturing solutions.

The two leading US companies operate with manufacturing plants in China (either on a wholly-owned or partner basis), and some 20 years ago the World Bank sponsored Marlec to set up a turbine manufacturing facility in Mongolia – which is one of the roots of the indigenous Chinese turbine industry.

While many of these businesses have had to be financially prudent, it would be incorrect to think of these companies as unprofessional amateurs (as is sometimes the perception). In fact, billion dollar industrial conglomerates such as ITT, Eveready, GE and Bombardier have invested in companies involved in this sector.

How easy is it to enter the market?

An extremely common misconception is that barriers to entry are very low. But to put together a professional organisation that can deliver – and continue to deliver (for the 20 year lifetime of a turbine) – an engineered product on a global basis against well-entrenched and motivated opposition is challenging.

• It appears to take a minimum of US$5-10 million over a five year period to gain an adequate foothold in the market. The best evidence for this comes from recent new entrant companies such as Windsave, Renewable Devices, and Quiet Revolution, and further evidence exists from the investment history of Proven and SWWP.
• It is widely believed that British company Windsave spent around US$7m between 2004 and 2009 on introducing a nominal 1 kW grid-connected wind turbine into the UK and other countries. Although many parts of the overall strategy were correct, some weren’t and the venture (by a wealthy serial entrepreneur) ultimately failed. The main Windsave trading company is now in administration after installing around 1200 wind turbines.
• Quiet Revolution (also British) received around £7m in funding commitments from the German utility RWE for its range of elegant spiral-shaped vertical wind axis turbines (VAWTs). In a four year period the company has installed about 100 wind turbines.
• The Scottish turbine manufacturer Proven made approximately 850 wind turbines in a 20 year period, prior to receiving funding from the venture capital fund LCA; LCA has since cumulatively invested £9m (US$13.5m) to take an 81% stake in Proven. LCA’s investments in Proven over a four year period have resulted in Proven’s total sales reaching some 2500 wind turbines, and the company now has around 70 staff.
• On the other side of the Atlantic the equally well known 50 kW turbines manufactured in Canada by Entegrity are no longer available, and the company is in the hands of the banks (owing at least US$11m and having laid off almost 80 staff in Boulder and Prince Edward Island).
• Further south, and Arizona-based SWWP recently received US$10m of investment, which is the latest in a series of investments over the last decade totalling some US$30-50m.

Clearly, if these well-established players need such large amounts of investment, and competent clean sheet start ups also routinely fail, it is curious that the industry is still generally perceived as one that is easy – and low cost – to break into.

On the face of it a small wind turbine has a similar level of technological complexity to a motorbike, and while there is realism on the part of bike hobbyists that becoming a mainstream manufacturer of motorbikes might not be trivial, this doesn’t seem wholly the case in the small wind turbine market.

This is not to say that new entrants should all give up and go home, but companies need to at least think very carefully before setting out to become commercial manufacturers. Even the availability of “off-the-shelf” wind turbine plans, and training courses from experienced sources such as Scoraig Wind (Hugh Piggott) and Otherpower (Dan Bartmann and Dan Fink), should not remove a dose of healthy caution from those wishing to enter the market – especially as these plans are not well suited to high volume commercial manufacture. In fact companies such as African Wind Power and Abundant Renewable Energy (now absorbed by Helix Wind) which tried to bring similar designs to market have struggled.

Another cautionary tale comes from Peru. At the 2009 European Wind Energy Conference (EWEC) it was revealed that an international aid-funded project spent US$400,000 to install almost 70 small wind turbines (of 1 kW or less) in the Peruvian highlands. This is very expensive for an off the shelf turbine, and there has been some confusion as to where some of the money went – project administration; reinventing technology; or are the real barriers to market entry elsewhere?

What about the subsidy question for small wind turbines?

In the battery charge market there is no need for subsidies, as the competition is solar power or diesel generators. Such technologies are relatively expensive after users take costs into account, and in an unsubsidised location clients tend to select an appropriate mix of the three complementary technologies after considering their own local resources (being sunlight, wind, or cost of diesel & maintenance).

But where there is a subsidy, the market is immediately distorted. For example, if, say US$400,000 of aid enters a market it can wipe out accumulated experience gained within a distributor network which was slowly but surely building up the knowledge required to begin producing wind turbines themselves without subsidies.

So such aid money perennially “resets the clock” on a dependency culture, rather than allowing the local economy to progressively move up the value chain. An example of such a well-timed move is the Japanese company Zephyr, which for many years imported SWWP products, and which now manufactures its own 1 kW turbine the AirDolphin (with about 2000 units built in the last five years). It is now backed by some major Japanese manufacturing companies, and they studied the industry very carefully before commencing production.

In the grid connected market things are slightly different and sometimes a subsidy is useful in levelling the playing field. But not always so. Most grid-connected electricity users are able to purchase electrical power at between US$0.10-0.15 /kWh, and in order for a small wind turbine to compete it needs support.

The advocates for support argue that such support levels the playing field with large-scale generation, which ordinarily gets support via a variety of mechanisms like the tax system. But the detractors for financial support argue that encouraging lower-scale proliferation of microgeneration technologies at point of use, is a diversion of funds in the subsidy pot away from large-scale renewable technologies that have a capacity to scale power generation rapidly – such as hydro, large wind farms, or even nuclear power in time.

Successful small wind turbine manufacturers have tended to be global in nature, as this insulates them from capricious changes in the subsidy environment in any one market. Successful new entrants into the small wind turbine industry have tended to come in at the 5-6 kW point with grid connected machines – examples being Iskra (now called Evance; 200; 5 years), Eoltec (200; 5 years) and most recently Kestrel of South Africa, and Endurance of USA.

There’s gold in VAWTS and urban wind

In the last few years a large number of vertical axis wind turbine (VAWT) manufacturers have advocated VAWTs as being the best way to harvest the chaotic urban wind resource, and some horizontal axis wind turbine (HAWT) manufacturers have been enticed by the vision of “a turbine on every home” – and the gold rush of riches that might flow from that dream.

Both visions have run straight into the problem of wind resource: there is limited wind in the urban landscape to make for cost-effective generation – given the low cost of the alternatives such as centrally generated electricity and the dense urban electrical distribution networks.

The question about whether there is enough wind in the urban landscape appears to have been conclusively answered by both the Warwick Wind Trial (WWT) and the Energy Savings Trust (EST) trials.

Both showed that the 'typical' urban wind resource is in the range of 2-3 m/s, which is insignificant when it comes to generating power from wind.

Both trials also indicated that while there are always localised exceptions to this rule, any densely settled landscape appears to act like the canopy in a forest – effectively resetting the ground level as far as the wind is concerned.

These two trials are also supported by theoretical work using computational fluid dynamics (CFD) models validated against wind tunnel testing. These have been carried out in the UK by Loughborough University and the Building Research Establishment; in France by Meteodyn; and in the USA by CPP consulting.

All these studies showed that as soon as the building density reaches that of a typical suburb or nucleated settlement, cost-effective small scale wind turbines become impossible because of a fundamental lack of wind resource. So irrespective of how cheap one could manufacture and install turbines, making them economically attractive would be a huge challenge.

The studies also showed that some micrositing opportunities may be feasible in certain circumstances, but it is not yet clear that pursuit of these microsites will pay back the high cost of running these relatively expensive CFD models.

Vertical axis wind turbine proponents believe that VAWTs are intrinsically better at dealing with turbulent wind resources – typical of the urban environment. However there has been limited testing to date, and no VAWT manufacturers were included in the WWT and EST trials.

Dutch utility Delta did run a trial in Zeeland which included four vertical axis units (including Ropatec, Turby, and Windwalker) and 7 horizontal axis units (Ampair, SWWP, Fortis, Renewable Devices, Zephyr). The Delta / Zeeland results show that at this site the better VAWTs produced 70-90 kWh/yr per m² of swept area, whilst the better HAWTs produced 120-230 kWh/yr per m². The Delta / Zeeland location has an average windspeed of 3.6m/s which is typical of a site on a European urban fringe.

Another trial of Quiet Revolution and Proven machines by London South Bank University on an 11-storey office block at Elephant & Castle in central London, UK, showed that the VAWT design had a negative capacity factor of -2%, whilst the HAWT design had a positive capacity factor of 4.6% – as measured over a 6-month period.

Although there may one day be a basis for preferring VAWTs over HAWTs in an urban location, it is more likely that neither will be suitable.

NB: Presentations on both these trials were given at the 2009 BWEA International Small Wind Conference & Exhibition (ISWC) which is rapidly becoming a key April event in the small wind calendar.

Another dedicated key event in the small wind calendar is the MREA Small Wind Conference that takes place in Wisconsin in June each year. At the 2009 conference, small wind commentator Mick Sagrillo gave a presentation that gathered together public domain results on some of the newer wind turbine entrants to the marketplace.

His first data set was on a US$100m turnover US-based company called Aerovironment, which ordinarily makes small aircraft and which has started manufacturing small wind turbines for mounting on roof edges. According to Sagrillo, a total of 6 kW of Aerovironment machines were installed on Government buildings in Duluth Minnesota, at a cost of US$51,000 – producing 400 kWh in 10 months (a payback of approximately 890 years).

His second dataset was on a spiral-shaped vertical axis wind turbine manufactured by the Finnish company Windside, installed at a cost of US$40,000 in Fitchburg, WI – which has generated 41 kWh in 7 months, giving a payback of 4761 years.

Sagrillo’s message was that whilst experimentation is good, product performance must be verified and certified so that consumers can buy with confidence.

The next article will discuss certification of small wind turbines and the progress that has been made in predicting wind resource.

About the author:

David Sharman serves on a number of small wind turbine committees including the international IEC and IEA committees; the USA NEC committee; and the UK committees of the MCS and the BWEA.

He is also the managing director of the UK wind turbine manufacturer Ampair.

He is a systems engineer with a BEng (Hons) from RNEC Manadon, and an MSc from MIT. Prior to Ampair he was an officer in the Royal Navy, and an operations and project manager in Shell.

He has lived and worked in many countries around the world including several years in Latin America. This article expresses his personal views.