Wooden Turbines

Norwegian company Hydra Tidal plans to test a tidal turbine next month. While many are pursuing different kinds of tidal energy devices, this one is unique for its turbine blades made of wood. Says company founder and R&D director Svein D. Henriksen:

“Wood is a porous, homogeneous material — so it has better mechanical and hydrological characteristics than today’s conventional materials such as composites and steel. The major challenge is the actual assembly process, but we believe we have found a good solution.” He points out that using wood in turbine blades is also an environmentally sound choice, especially in a lifecycle perspective.

That wood is porous doesn't seem very significant, especially since the pine they plan to use is laminated. Many other materials are "homogeneous" too and the lifecycle advantages are rather minor. At 23 meters long, blade durability may be an issue too, and frequent replacement of weaker blades is no lifecycle or environmental boon. The allegedly better mechanical and hydrological aspects are not further described.

The plan to use floating deployment (as Hydrovolts does) is smart as it is faster, simpler, much cheaper, and doesn't need specialized boats. Still, the technology itself doesn't seem particularly different otherwise, apart from the wooden blades. So, why wood?

80% of the [turbine] can be recycled after its life span, which is more than 30 years. For example, our turbines are made out of glued wood. This material can handle tough ocean environments and they last very long. After the turbines' life end, they can be chopped and used in a bio energy power plant for example.

Hydra Tidal has, in cooperation with Harstad University College and Kunnskapsparken Nord AS(Science/Competence park), made a report about CO2 emissions in connection with the production of a complete Morild power plant. CO2 emissions are 40% lower than that of onshore wind power.

They've done some very clever things in Norway with renewable energy, so it will be worth watching to see how this turns out.

The Hydrovolts Turbine

I've been spending a lot of time on posts about some of my passions--renewable energy, climate change, energy politics, and other things--I haven't spent nearly enough time on Hydrovolts technology. So, let's talk turbines.

First, some terminology:

• A turbine is the complete device, containing all parts that turn moving water into electricity, and especially the rotor, the generator, and the power electronics.
• A rotor is the part that spins in the current. For most turbines this looks like a propeller made of several blades, often similar to those used in modern wind turbines (but smaller and proportionally thicker.)
• The generator converts the mechanical energy (typically of a rotating shaft) into electricity through the use of magnets and wire windings.
• Power electronics take many forms but for turbines are necessary to both transform the electricity produced by the generator into the right form (e.g. AC or DC) and to condition the power by smoothing out voltage spikes, reducing line noise, etc.
• One important kind of power electronics is the inverter, which changes direct current (DC) into alternating current (AC). AC is used in the electrical grid, the wires in our homes and many large appliances. DC is used in cars, consumer electronics and most battery devices.
• A power cable brings generated and conditioned electricity to where it is used or to a point of transmission.
• Deployment hardware provides a way to position the turbine in service. This hardware varies widely with the size of the turbine, its type, and details of the site.

Hydrovolts is building small in-stream hydrokinetic turbines to create clean, renewable energy. The initial prototype is meeting all development objectives.

A key element of the Hydrovolts turbine is its unique rotor design. Most hydrokinetic turbines use a horizontal axis design where the axis of rotation, the shaft, is positioned parallel to the current flow. The moving current presses on two or more blades mounted radially from the shaft, causing it to rotate. Examples include the design from Marine Current Turbines:
Verdant Power has a 3-bladed design they have been testing in New York's East River (actually a tidal flow rather than a true river.) The mounting pylon is designed to rotate, allowing the turbine to capture power both on the incoming and outgoing tides:

The Clean Current turbine has several blades and differs from the previous two by placing the spinning blades in a cowling. This both allows a venturi effect to increase the speed of the water flow and somewhat shields marine life from the fast-moving blade tips:

These three designs all use horizontal axis rotors as part of their hydrokinetic turbine designs, but these companies are pursuing a different business from Hydrovolts. All primarily target utility scale power generation in tidal flows rather than small scale generation in freshwater flows. Hydrovolts business grew out of founder Burt Hamner's successful effort directing a study for Tacoma Power to assess the feasibility of tidal energy in the Tacoma Narrows. The study concluded and Tacoma Power agreed

that tidal generation will not be feasible in the Tacoma Narrows waterway for at least eight to 10 years and that other renewable resources, like wind power, are more economically feasible at this time.

Burt realized that, although feasible tidal power remained a distant prospect, the same kind of hydrokinetic technology could be shrunk down and deployed in many other places in a way that would have near-term feasibility.

Some other companies have had a similar idea.

Hydro Green Energy intends to place utility-scale devices using a horizontal axis design in permanent installations adjacent to existing hydroelectric dams. They installed their first 100kW unit in Hastings, MN a few months ago:

Free Flow Power has aggressively pursued Federal Regulatory Energy Commission (FERC) permits in the Mississippi River to place arrays of horizontal axis turbines, each with 7 blades:

Unlike these others, Canada's New Energy Corporation (EnCurrent) uses a vertical axis design. The rotating shaft extends from the rotor blades in the current flow up through a deploying raft to the generator and electronics above the surface:

The Hydrovolts rotor design is different from all of these, as it uses a cross-axis design where the rotating shaft is perpendicular to the water flow and parallel to the water surface. The design is similar to a paddlewheel or old-fashioned water wheel with one very significant difference: the Hydrovolts design is fully submerged. It is like a paddlewheel that can spin entirely under water:


The Hydrovolts cross-axis design has several significant advantages over competing designs:

• Simple: The flipwing blades are flat sheets rather than more complicated propeller blade designs. Flat blades can be made in many places and of many materials without expensive machinery or costly tooling.
• Robust: Because the blades are simple the turbine suffers little loss of efficiency if they are damaged, e.g. by denting or warping. Foil designs will be more severely impacted.
• Safe: The Flipwing turns at the speed of the current and has no tips or edges that could slice marine life, e.g. fish.
• Low fouling: Initial tests show that water-borne debris rolls over the top of the Flipwing, unlike with horizontal axis turbines which become easily entrained with material that wraps around the shaft.
• Adaptable: Almost all competing designs have a swept area (the working cross-section of the current) that is circular, so non-circular channel geometries cannot be efficiently harnessed. The Hydrovolts Flipwing is rectangular, and can be built to exactly match water flows of different dimensions, such as those that are wide and shallow.
• Scalable: The Hydrovolts Flipwing design can be manufactured to fit watercourses of almost any size both by scaling the individual device and by ganging together multiple turbines to maximize the swept area of an available channel.
• Easy Deployment: The Hydrovolts turbine is fully submersible and floats in the current. No watercourse modification (dams, penstocks, pilings, poured concrete) is needed. The turbine can literally be tossed in and held in place with deployment hardware as simple as two chains anchoring the turbine to each bank. (Other deployment hardware and options are available.)
• Low Cost: Simple rotor design, easy installation, and a compact design keep manufacturing and deployment costs low, resulting in much faster capital ROI for buyers.

Initial in-water tests like that in the video above demonstrate that the device spins when entirely under water at a speed that matches the flow of the current. Subsequent testing using a custom-designed raft produced RPM, torque, and power numbers in line with theoretical predictions. The rotor was fixed in the water below the raft, and a chain drive was used to bring the rotational characteristics above the waterline to the monitoring and test equipment:

The raft was placed in the water and towed behind a research vessel at carefully calibrated speed, simulating the current flow of a stationary turbine in a flow of the same speed:

The Hydrovolts team used these and other results to improve the prototype design and to attach an initial generator design:

Company founder and Flipwing inventor Burt Hamner has continued to lead the Hydrovolts effort to produce a new generation of improved hydropower devices:

Further in-water tests using the boat-tow method continue to yield good results:

Recent lab test results validate the power output Hydrovolts expects its production units to make. Additional prototyping work is ongoing. While there are various design and optimization issues still to be finalized, we are pleased with the excellent results and the rapidity of our current progress. Based on the prototyping success, Hydrovolts is building the first of several demonstration units:

This unit will be placed in service within the next 3 months, with others to follow based on the needs of our development effort and based on feedback and interest from our customers.

Those interested in learning more or hosting a demonstration unit are invited to contact us.

Power from water^TM. The light bulb is on!

Solving the Variability of Renewable Power

An oft-repeated problem with renewable sources such as wind, solar, wave, and tidal is that they are variable. When the wind is not blowing or the sun is not shining then they don't produce power; conversely, there are times where more power could be produced than could be used. This variability, often exacerbated by its unpredictability, has significant implications, especially for utility-scale generation that is connected to the electrical grid.

Current grid management is, in its simplest form, the matching of electrical generation and electrical use, the matching of supply and load. Electrical grid managers are able largely to rely on the load profile, the historical variation of the load over time. There are two basic techniques today to match generation and load: generate additional electricity from various sources when needed (the usual approach) or reduce demand (demand response, much less common.) A detailed explanation can be found here:

The power utilities are able to predict to a reasonable accuracy (generally to within one or two percent) the demand pattern throughout any particular day. This means that the free market in electricity is able to schedule just enough base load in advance. Any remaining imbalance would then be due either to inaccuracies in the prediction, or unscheduled changes in supply (such as a power station fault) and/or demand. Such imbalances are removed by requesting generators to operate in so called frequency response mode (also called frequency control mode), altering their output continuously to keep the frequency near the required value.

The grid frequency is a system-wide indicator of overall power imbalance. For example, it will drop if there is too much demand because generators will start to slow down slightly. A generator in frequency-response mode will, under nominal conditions, run at reduced output in order to maintain a buffer of spare capacity. It will then continually alter its output on a second-to-second basis according to the needs of the grid.

This spinning reserve is a significant expense to the power utilities as often fuel must be burned or potential power sales lost to maintain it. The kind of generation used for fast response is usually fossil fuel powered which produces emissions of between 0.48 and 1.3 tonnes of CO2 equivalent for every megawatt hour (MWh) generated. Thus a significant environmental burden, in the form of increased greenhouse gas emissions, is associated with this imbalance.

Most forms of generation are unsuitable as peaking power plants (peaker plants, spinning reserves) because they cannot be efficiently started/stopped or operated on an intermittent or sudden demand basis. As a practical matter, only natural gas turbine generation can serve as peaker plants. This is the core reason why T. Boone Pickens, Chesapeake Energy and others are so interested in wind power--it will increase demand for natural gas.

Thus the paradox: the desire to add renewable sources of electrical generation is motivated in part by the need to mitigate climate change; however, the addition of variable renewable sources increases the need for spinning reserves, which currently adds to the carbon problem.

What to do? What other than natural gas, with its carbon footprint problems, could serve as a spinning reserve or, more broadly, as a peaking power plant or some kind of load following capability from storage that would enable near-instantaneous supply increases to respond to changes in the electrical demand?

An alternative is grid energy storage. With the growing interest in and development of electric vehicles, especially plug-in hybrid electric vehicles (PHEVs) some have suggested that a growing array of distributed batteries in PHEVs could serve as a source of additional electricity in periods of high demand.

The concept, called vehicle to grid (V2G), is based on the fact that your car is typically not being used 90 percent of the time. "What if it could work for you while it sits there?" said Jeff Stein from the University of Michigan.

The National Science Foundation has granted a research team lead by Stein $2M to explore the possibility of V2G technology using PHEVs. There are many problems to be solved, however. The cars would need to be plugged into a socket not just when being charged, but also so electricity could be drawn back out. How would this be controlled? No PHEV owner will be happy to wake up in the morning and find the battery (half-)drained after being plugged in all night, presumably charging. There are (potentially significant) efficiency losses in charging/discharging batteries, and the life of the batteries would likely be shortened by an arbitrary cycle where complete charge or discharge may not occur. Lastly, there would need to be substantial elements of a future smart grid deployed to even allow this distributed storage to be harnessed in a centralized way. Interestingly, there is already a test of this concept underway at the University of Colorado (Boulder) by Xcel Energy. Other tests are also underway by Southern California Edison, Austin Energy, Duke Energy, Wisconsin Power, Excel Energy, and Pacific Gas & Electric, amongst others.

Hydro is another mostly green approach. Here in Washington state we get about 70% of our electricity from conventional (big dam) hydroelectric power, which has the ability to serve as a peaker plant by letting more or less water flow out of the reservoirs and through the turbines. There is competition for the water, however, especially from irrigation, but also from navigation and fisheries concerns, so the degree to which these dams can serve as peaker plants is somewhat limited.

Pumped storage hydroelectricity is another storage mechanism that might be explored, and may be very well-suited in coastal settings with large amounts of ocean energy generation (offshore wind, wave, etc.) Some of the drawbacks of this form of energy storage would be mitigated by a reservoir built for the purpose, rather than the use of a pre-existing (freshwater) lake.

Storage could also be achieved via flywheel arrays, hydrogen generation, compressed air, or other techniques.

Longer term, an updated, expanded, and smarter electrical grid is necessary. Wind generation is more variable the more local the scale and geographic reach of the turbine array. As more wind generation comes on line in greater density and over a more diverse, interconnected geographic area, local variations even out and become less significant. Offshore wind, despite its higher cost has several significant advantages over onshore wind; a large one is greater wind (power) on a steadier basis. Large coastal arrays (example) would take out some of the variability.

1GW of Ocean Power by 2015

A Greentech Media report announced today predicts installed wave/tidal power capacity will grow from less than 10MW today to 1GW by 2015. The report also states that about $500M has been invested thus far in ocean energy technology research and development, but projects this to quadruple over the same time period to $2B. An additional $2B will be invested on deploying ocean energy farms.

(There's apparently lots more good stuff in the report, including time lines, supply chains, technology comparisons, policy drivers, utility influences, etc.; but since it costs $2,995 I can't afford to read it. Anyone want to lend it to me?)

Renewable Energy incentives enacted

The house comfortably passed the Splurge and the President has signed it into law. That's the good news. The bad news of course is that we taxpayers are now on the hook for another $700B of good money after bad with little indication that there won't be another "emergency" next month or next week.

The bill also includes provisions for disaster relief, mental health, and random other.

The renewable energy portions are basically good, although lacking some provisions that might have been adjusted or added if there had been more time and deliberation. But then, maybe we would have got less too.

Energy provisions of note:

Sec. 101 extends the renewable energy credit for wind for one year. AWEA and others make a compelling argument that a one-year extension is too short. Bizarrely, "refined coal" also gets this "renewable" energy credit. (I suppose coal could be renewable if enough life dies out and we just wait long enough.)

Sec. 102 provides the PTC for "marine renewables" which include the obvious wave and tidal, but also ocean currents and energy produced from the "free flow" of rivers, canals, etc., which is excellent news for Hydrovolts. The provision applies to equipment placed in service before 1/1/2012.

Sec. 103 extends the credit for solar out to 12/31/16.

Sec. 104 provides for a credit for small wind (less than 100kW) and increases it from $2000 to $4000.

Sec. 105 provides credits for geothermal heat pump systems.

Sec. 106 "clarifies" (as only the Government can!) residential rules for credits for small wind and geothermal.

Sec. 107 provides $800M of new Clean Renewable Energy Bonds (CREBs).

Sec. 117 requires a "carbon audit of the tax code" by the National Academy of Sciences who is tasked with issuing a report in 2 years.

Sec. 304 extends the new energy efficient home credit by one year, and Sec. 305 provides credits for energy efficient appliances.

Sec. 306 allows accelerated depreciation for "smart grid" hardware.

Sec. 404 extends the federal unemployment tax another year. No doubt some would call this a "tax increase" but it's more accurately termed a decision to not provide a tax cut.

There's a lot more stuff to help the steel industry, the coal industry, the oil and gas industry, the Black Lung Fund, for carbon sequestration, biofuels, plug-in electric vehicles, to encourage bicycle commuting, to dicker some more with the Alternative Minimum Tax (AMT), and clauses (whether intentionally so-designed or not) to further complicate everyone's tax return.

There are also some of the clauses quickly becoming infamous, such as Sec. 502 for Hollywood producers and Sec. 503 providing an exemption from tax for makers of wooden arrows for children. I can see the entertainment industry having the clout to stuff this in, but the childrens' archery lobby?

Glad to get at least enough on the renewable energy front to tide the industry over into the next Administration which will have the opportunity to do a thorough top-to-bottom restructuring of our energy economy and perhaps both simplify the rules and better align tax policy to a a sensible and realistic energy policy that addresses climate change, energy security, and the creation of jobs. The renewable energy industry is still in its infancy; our government has the opportunity to make the US a leader as it grows into the next global industry.

UK-Pacific NW Marine Energy Mission

I spent all day on Monday at the Bell Harbor Conference Center with maybe 75 people involved in or interested in the renewable ocean energy industry. There were many excellent presentations and ample time to network and discuss areas of mutual interest. Sadly I couldn't talk to everyone and I missed bits of some presentations because I got engrossed in conversation... I forced myself to take some notes to try to capture some of the good bits.

This was the first stop on a week-long trade mission by a dozen or so entrepreneurs and other business people from England and Scotland. I'm a bit slow getting this post up; by now they've been and gone from Portland, OR (Wednesday) and are now down in Coos Bay for the Oregon Wave Energy Trust (OWET) Ocean Renewable Energy Conference. (Sorry I couldn't go to that one myself, but I have to do some "real work" at least part of the week ;-)

The event was organized by UK Trade and Investment and promoted by PNWER. Local organizing assistance came from the British American Business Council of the Pacific Northwest, Port of Seattle, WA Clean Tech Alliance, Washington Technology Center, Washington State CTED, OWET, and Oregon ECD. Sponsors included The North of England Inward Investment Agency, Ricardo, Scottish Development International (SDI) and Stoel Rives.

LA vice-consul Michael Rosenfeld of the UK consulate and Graham Evans of the WA Clean Tech Alliance traded off as masters of ceremonies; both did a splendid job keeping the sessions on track and on time, making introductions and injecting sufficient levity to keep all engaged.

Steve Klein, CEO of Snohomish PUD gave the morning keynote and talked quite a bit about SnoPUD's renewables plans. Of greatest interest to me was his flat assertion that "no fossil fuel generation will be added to our portfolio." Given their load growth of 10-12 thousand new connections and 15-20 aMW per year--amongst the fastest in the state--this is a remarkable statement. A lot of people are assuming Washington's future electricity demand will be met with liquid natural gas (LNG) thermal plants and/or Canadian imports (probably also LNG) but, as Steve stated, this is not a part of their Integrated Resource Plan (IRP). Instead, they intend to meet demand through conservation, wood waste/landfill/biomass, "cows" (is he serious?), and geothermal, taking advantage of their position on the Pacific "rim of fire". Interestingly, they plan on geothermal being the largest source of new energy (after conservation) with wind next. Small hydro and tidal are expected to be only small contributors at only 5 aMW each by 2020. They are also pursuing tidal energy in Puget Sound; he said that there "could be 100 aMW of tidal [energy] in Puget Sound ... [but] nobody really knows." I'll write more on this later.

Steve spent some time talking about wind energy; he has several "worries":

• they've added 10GW in the last 2 years, and problems are starting to show
• the wind doesn't blow much when it is very hot or very cold--when energy demand is greatest
• it is not predictable
• cost of wind is going up (not down)--as much as doubled
• the devices have mechanical issues (especially the gearboxes)
• SnoPUD isn't "putting all the eggs in the wind basket" (I think it's clear they're going to hard-boil them with geothermal!)

Scott Amsden of Tacoma Power talked about the results of their assessing tidal power in the Tacoma Narrows. This was a project done by my business partner Burt Hamner and Puget Sound Tidal Power. You can read all about it here.

Naval architect Charlie Nordstrom of the Glosten Associates gave a very interesting presentation on the growing interest in offshore wind and some details of the Trillium project that he and his firm are pursuing in Lake Ontario. Offshore wind has challenging logistics, foremost of which are the size and weight of the components and the enormous deamnds that these place on the equipment used to transport and install the turbines. For example, the 5MW turbines used in the Beatrice project in the UK require an approximately 800 ton "pick" or lift by a marine crane, and there are not very many such cranes. Also, since the weather conditions have to be right to do the picks, progress can be slow--Charlie noted that it took most of the summer to do just 2 installations. Not only are the demand on the equipment great, but there isn't very much of the right equipment available. On the west coast there are only a handful of cranes that can pick more than 500 tons. Glosten Associates are designing a 1000-ton crane for Manson Construction, which, when built, will be the largest crane available. At Trillium they are planning to use the Jumping Jack to do the installation. An additional constraint on offshore wind (or other energy projects) is the Jones Act, which basically prevents ships from other countries being used in US waters. (Of course, there aren't really any such ships available--in Europe they are all booked years out.)

Charlie identified the following best practices for offshore wind construction:

• minimize at-sea work
• design for installation
• keep expensive assets busy
• rely on operators' experience
• use existing equipment
• know your site conditions
• plan for equipment availability

Later in the afternoon Paul McKeever of NaREC added two more to this list:

• have equipment redundancy
• strategically purchase spare parts

After a break, we heard from the UK companies; I'll write about that in a later entry.

At lunch (great food!), Roget Garratt, Director of Resource Acquisition & Emerging Technology for Puget Sound Energy (PSE) gave the keynote, talking about PSE's customer base, growth, and generation plans. Afterwards he took some questions; the best was asked by Burt Hamner: in its IRP what does PSE anticipate will be the cost of energy in 2020? A quick glance around the room confirmed that this was The Question that many in the renewable energy industry really want to know. After all, if you are a project developer in renewable energy or part of the supply chain for the technology, you really need to know the price at which the customer will buy. Of course it gets a lot more complicated when once considers the (on-again/off-again) credits, potential penalties for not meeting the RPS, etc. but it all starts with the core COE. Although Roger answered the question he never gave a number. Does PSE consider this information proprietary, not wanting to let the other utility officials in the room know their planning numbers?

In the afternoon there were several panel discussions and they were pretty interesting--so much so I find that I neglected to take very many notes. Charlie Brandt of PNNL, Tim Stearns of CTED, Sheila Hosner of the Washington Department of Ecology and Mary Jane Parks of Principle Power discussed permitting and regulatory issues. Short story--there are a lot of agencies and permits needed to do any kind of offshore project, but the authorities are not awful to work with as long as you follow the process. Sheila recommended proactively keeping them informed, beginning long before you even file something. In that repsect it's rather like applying for an SBIR or other government grant--spending quality time with the program manager and building trust through constant communication really pays off. Sheila also represents the Governor's Office of Regulatory Assistance which has been established specifically to help companies wend permits through regulatory offices. Later, in wrapping up the day Graham Evans noted that many of the speakers (not just in this panel) agreed that "embracing" the regulatory process--not fearing, but cooperating--was the best practice for getting regulatory and permitting approval.

Burt Hamner gave a lucid overview of the Grays Harbor Ocean Energy project he and I are pursuing off the Washington Coast--the only proposed offshore wind project on the US west coast, and the only one with a FERC permit.

Brian Polagye of the University of Washington, Bob McClure of BioSonics and Paul McKeever of NaREC discussed R&D directions and emerging technologies in their panel. Bob's presentation was particulalry interesting, detailing his firm's state-of-the-art hydroacoustic technology to assess fish and aquamarine populations to astonishing levels of detail. Verdant Power and many others are clients using their equipment and know-how to assure that their marine energy equipment is compatible with the local species.

There was a lot more going on than I can write here, and lots of excellent information, ideas, and exchanges. Graham stated, to broad agreement, that this was just the beginning of such collaborative meetings, and that there is much more information, expertise, and lessons learned that are still to be shared. I know I speak for many participants in saying that I am keenly looking forward to the first quarter of 2009, when the reciprocal trip of NW ocean energy companies and people will journey to the UK to see what they have there and talk to those involved in more detail. Sign me up for that trip--it's going to be too cool!