In response to the question, “how to generate more power under low wind speed conditions”, here are some basic points to keep in focus. This is a good question, which is far-reaching and includes a discussion of how to produce and sell electrons at an economically viable price.
A study of constraints in the wind industry was conducted to guide the development process of the Uprise machine. The list is long, but here are the ones that effect energy capture are:
- Rotor RPM constraints
- Generator RPM constraints
- Power factor
- Parasitic losses
- Pitch stall impact on blade shape
- Blade area
Uprise innovations have eliminated all of these constraints
- The rotor is allowed to change RPM as the wind speed changes. This maintains the optimum tip speed ratio, which is known to optimize energy capture.
- The Uprise generator is driven at a constant RPM, which allows the use of a synchronous vs induction generator. The Uprise drive system eliminates the need for a fixed ratio gearbox. Voltage and frequency from a synchronous generator are maintained, eliminating the need for a transformer and an inverter.
- Conventional wind machines utilize induction generators, which produce lagging power factors, and require KVARS from the grid to excite the field coils. This decreases net output of the machine by 20-30%. As wind speed and rotor load drops, voltage drops, and excitation amperage increases, causing a lug on the rotor, which reduces low wind energy capture efficiency.
- Parasitic losses, namely line losses due to inefficiencies caused by the gearbox, transformer, inverter, and KVARS, amount to an additional 25-30% loss as compared to the Uprise drive system.
- Overloading of the blades, gearbox, and tower from wind gusts and high wind speed is a serious constraint. Conventional wind machines limit blade count and blade area to prevent overloading. As a result, low wind speed energy capture suffers. The Uprise machine incorporates 5 blades to improve low wind speed energy capture, as well as other benefits, such as low blade loading, lower noise levels, less toggling, and smoother operation. Unlike a conventional machine, an increase in rotor RPM on the Uprise machine is actually sought after. This is only one of the ways the Uprise machine increases energy capture. Ultimately, wind strength can overload the Uprise machine. In such a circumstance, the Uprise machine will automatically shut down and lay down to mitigate damage.
- Conventional blades are designed to prevent overloading and over speeding thru pitch stall. This is a constraint. Pitch stall is designed into the blade shape so that the blade can quickly rotate to “null” the load of a high-speed gust, and to prevent an increase in RPM. The downward slope of a conventional power output curve is the result of pitch stall. The Uprise machine is designed to manage wind gust energy capture, rather than blunt the power. The blades on the Uprise machine are not compromised by a pitch stall shape.
- Torque on a conventional wind machine increases dramatically at high wind speeds. This is due to the fact that load increases without an increase in RPM. The RPM of the Uprise machine increases with load, and as a result, torque and drive train loads are significantly lower, resulting in a lighter machine and longer life.
When reviewing electrical power options for remote (often times off-grid) regions, there are three primary options one would likely consider: Solar Power, a Diesel Powered Generator or a Wind Turbine.
Comparing these three is interesting, but not always equivalent.
For this example, we’ll use a typical scenario for the Uprise Energy 50kW portable wind turbine as the basis for comparison. In an average wind speed of 12mph, the Uprise Energy Portable Power Center (PPC) will produce 12kW of electrical power. When factoring the cost of the machine, along with operation and maintenance expenses over a 20 year lifecycle, an average windspeed of 12mph will equate to an energy cost of 10 cents per kilowatt-hour. Stronger wind conditions will reduce energy costs, with potential to be as low as 3 cents per kWhr. Maximum power of the Uprise Energy portable wind generator is 50kW.
In contrast, if a 50kW diesel generator were used to produce 12kW, it would have very poor efficiency (BSFC), so a 15kW generator should be chosen. To produce 12kW/hr, the diesel generator will burn a minimum of 1 gallon of diesel fuel per hour, depending on efficiency or a minimum of 175,200 gallons over 20 years IF it is properly loaded.
Diesel fuel is the most power dense, relatively portable and reliable.
Diesel fuel is also the most expensive, non-renewable and produces greenhouse
gasses. A best-case diesel power scenario would be an initial generator cost of $20,000 plus
$1,000,000 in fuel costs. Shipping, operation and maintenance expenses would
also need to be added. Depending on load factor (BSFC) and cost of fuel, a
diesel generator will make power in the range of $1 to $40 per kWhr.
Maximum power is limited to 15 kW.
A solar system's capacity factor is about 12%; therefore, a 100 kW system must be purchased to produce an average of 12 kW. The average panel size is 18 SF, costs $400 and produces 200 watts when new and then degrades from there. Additional losses occur from inverter and transformer heat, plus extra cost to service, maintain and replace panels as needed.
A 100 kW solar system would extend approximately 10,000 SF and requires a significant installation mounting system. Unlike the Uprise Energy Portable Power Center and diesel generator, a solar system is not portable and requires well over 10X the space. Lifecycle costs for the solar array is approximately $300,000 with a best-case average cost of 19 cents per kilowatt-hour. Maximum power is limited to 100 kW at peak sun angle, which is not realistically achievable. Due to the limited power production throughout the day with a solar system, the need to store power is elevated unless another form of power is available to the consumer.
In summary, when 12kWhr is the goal and a 20-year lifecycle is applied, these are the expected costs per kilowatt-hour:
- Uprise Energy Portable Power Center $0.12/kWhr
- Diesel Generator $1-40/kWhr
- Solar Power $0.19/kWhr (inconsistent power, not portable, largest footprint)
If you have questions about the above or would like to continue the discussion, please use the comments section below. Thanks for reading!
Electrical energy provides great benefits to those who are connected to a grid. For the billions who are not connected to a grid, the solution is local or portable power generators.
Virtually millions of small communities, remote and isolated, need small or medium generators.
Fuel powered generators are high in cost per kWhr, fuel supply is risky and unreliable.
The solution is generating electricity renewably, where it is needed.
While wind turbine technology is proven, small wind turbines are inefficient and unaffordable, and while utility scale wind turbines are affordable on a cost per kwhr, they require large capital commitments and are not suitable for mid-size communities.
The solution is an efficient and affordable mid-size wind turbine that is conveniently delivered, set-up, operated, and maintained.
Introducing the UPRISE Energy Portable Power Center (PPC), an innovative 50kW wind energy electrical generator that is:
- Mid-size, makes meaningful power in light and medium wind speeds
- Portable, ships in a standard container, travels on any road
- Efficient throughout a broad wind speed range
- Affordable, lower in cost per kWhr than utility, solar, diesel
- Set-up by 1 technician in 1 day, no site improvements, no cranes required
- Automatic / Autonomous operation with telemetry
- Maintenance performed at ground level
- Stand alone, connect to grid, operate in multiple units, net meter
- Store energy
- Infinite ratio fluid drive system
- Sweep and twist blade technology
The Uprise Energy Portable Wind Turbine is truly like none other and stands to serve a very large and important niche.
Rated output, also known as Nameplate rating, is determined by the wind turbine manufacturer, based on their chosen wind speed. The rated output can be a high number or a low number, depending on the wind regime chosen for performance calculations. In its current state, there is no unified approach to wind turbine ratings, making the process capricious.
Actual net output is not affected by output rating, but capacity factor is, since capacity factor is a percent of the output rating.
If we say that a machine is rated at 50kW and it delivers 20kW on average, its capacity factor will be 40%. If we rate that same machine at 60kW, the average output remains the same but the capacity factor changes to 33%.
You can start to see how nameplate rating (output rating) and capacity factor are arbitrary.
Most good performing machines average 25% of rated output, a very good machine will deliver 35%, but again, these percentages are based on the wind turbine maker's chosen power rating.
Imagine the scenario where a manufacturer wants to give the illusion of a high output machine; they could use performance figures from unusually high wind speeds, utilize a generator big enough to support these unrealistic wind conditions and presto, they've got virtually whatever size machine they want. Not only is this deceiving to the consumer but utilizing a generator that's too big for the application drives the cost up and hurts efficiency.
So, since there's no industry standard for wind turbine power ratings, what's the best way to compare machines?
Cost per kilowatt hour.
Output per square foot of footprint or swept area is another way to compare apples-to-apples but the one we use most frequently at Uprise Energy is $/kWhr.
If you have another metric that you use or would like to continue the discussion, please use the comments section below. Thanks for reading!