Redfield Tidal Report

Redfield Consulting is pleased to announce that its updated Tidal Energy Report is now available.  Covering more than 150 tidal energy devices, and reviewing the top 20 in more detail, the report provides an authoritiative and objective overview of the current state of the tidal stream energy sector.

For device developers, it provides a review of the competitive landscape; for potential investors, it permits identification and high-grading of potential investment opportunities.

It is available as a pdf for £295+VAT, or in hardcopy for £350+VAT.  More details are available in the flyer available at http:www.redfieldconsulting.co.uk/Redfield Tidal Report flyer.pdf

If you’d like to order, would like further information or have any questions, please contact Redfield Consulting, at reports@redfieldconsulting.co.uk

Tidal devices - performance review

Following the Scottish Renewables Marine Energy conference in Inverness, a couple of interesting performance metrics emerged.

Atlantis recently announced that the MeyGen project had generated 700 MWhr during August, apparently from 2 AndritzHydroHammerfest (AHH) turbines.  We thought it might be interesting to extract an average capacity factor from these figures.

2 turbines at 1.5 MW - 3 MW installed capacity.

Number of hours in August: 31 * 24 = 744

Total potential output = 744 hours * 3 MW = 2.232 GWhr

Actual output: 700 MWhr

Capacity factor: 0.7/2.232 = 31.4%

This may be a slight over-estimate, as the third AHH turbine may have made a minor contribution late in the month following its re-installation, but even with that proviso, these are not bad figures for a full month (i.e. neaps and springs).

ScotRenewables made a similar claim - that its 2.0 MW SR2000 had generated 116 MWh over week.  This equates to a capacity factor of 116/(24*2*7) = 34.5%, and we understand that this period was intermediate between spring and neap tide.

As runtimes extend and reliability improves, we hope to see these numbers go up too.

Hours on the clock

Marine Current Turbines have now racked up 1000 hours of export to the National Grid, as reported here.

MCT claims an average capacity factor of 66% for the period of operation. We have calculated a capacity factor, based on ROC register figures, which shows a steady(ish) increase to around 25% in November 2009. This calculated CF does not make any allowance for downtime, availability of marine mammal onservers, or (crucially for MCT) the limitations imposed by daylight-only working.

Since daylight in November is less than 50% of the time, and the trend is upwards, we can see that a claimed 66% capacity factor in December could be realistic.

If true, it's excellent news for the company and the technology, as it's always all about cost per MWhr, and more MWhrs means a better metric.

MCT power curve - analysis

MCT has just published a power curve for its Seagen device in Strangford Narrows (see figure above and link here). The curve shows a period of output at the design capacity of 1.2 MW, in what is described as a “medium tide”. This tide appears to have peaked at 3.1 m/s, which may be medium for Strangford, but is pretty impressive for most sites.

We realised that it’s possible to drill into this curve to come up with some (very) theoretical ideas of the capacity factor which might be achieved by the technology. First we constructed a velocity lookup table by taking a ruler to the graph, which shows the power output (kW) at various stream speeds (m/s).

m/s - Power
0 - 0
1 - 20
1.25 - 100
1.5 - 180
1.75 - 400
2 - 600
2.25 - 900
2.4 - 1200

We then constructed a model which characterises a simplified tidal environment, with stream speed varying according to a diurnal cycle (sinusoidal variation over 24 hours, in 2 flood, 2 ebb tides) and a 28 day lunar cycle (again simple sinusoidal variation).

We entered a maximum stream speed (peak rate achieved at spring tide) and a minimum stream speed (peak rate achieved at neap tide) and constructed a lookup on an hour by hour basis to estimate the power output over a month.

Based on a maximum stream speed of 3.2 m/s and a minimum stream speed of 1.6 m/s (ie neap maximum is half as fast as spring maximum), we find that the average theoretical power output (assuming no outages) to be 450 kW, making the capacity factor 38%.

The model shows that output is sensitive to both maximum stream speed and the ratio between spring and neap peak rates. The table below shows the relationship between capacity factor and the maximum stream speed) assuming that neaps are limited to 50% of the maximum stream speed in springs. The month-average capacity factor for various maximum spring stream speeds is:

m/s - CF (%)
2.8 - 28%
3 - 34%
3.2 - 38%
3.5 - 45%
4 - 53%
The table below shows how the capacity factor is influenced by the ratio between the maximum neap speed and the maximum spring speed based on a maximum spring stream speed of 3.2 m/s. The table shows maximum neap speed and month-average capacity factor.

m/s - CF (%)
0.8 - 31%
1.2 - 33%
1.6 - 38%
2.1 - 45%
2.4 - 48%

All of these power output estimates are wildly theoretical – and should be treated with extreme caution. Next we’re going to combine this power curve with some actual tidal data from tidal diamonds on charts to see how that looks.

42 bids!

The Crown Estate has announced that it has received 42 bids from 20 organisations for Pentland Firth leases.  Apparently lease applications for sites from 10 MW to 300 MW have been received, across a range of technologies and technology types (wave and tidal), and from small developers all the way up to large multi-national energy companies (I wonder if they mean oil companies, utilities or both?)

It seems to us that there is some risk here that bidders may be tempted to "land-bank", tying up sites without serious near-term development plans.  I hope the Crown Estate is sensible enough to try to make sure that only really credible companies are awarded leases in the most energetic areas.  We worry that putting today's devices into the Pentland Firth is like racing a Model T Ford around Brands Hatch - pushing early stage technology too far.

So while we're pleased at the level of interest, we hope that lessees are conservative in rolling out their technologies to less energetic sites first.

Thirty Eight!

The Crown Estate has just announced that 38 companies and consortia have been invited to tender for leases in the Pentland Firth lease round.

Obviously there's no public information on who the 38 are, but it would be interesting to know.

OpenHydro's got themselves a boat

Irish tidal stream energy company OpenHydro have commissioned their new dedicated barge (at a cost of €5 million) to enhance their capacity to install and maintain their equipment.

This is the first specialist bit of equipment I've heard of, and it's a strong statement of intent by OpenHydro. And better than that, it works!

Nothing new under the sun (or waves)

Interesting article in the Guardian today about a horizontal axis transverse tidal turbine: a cylindrical rotor is placed across the tidal stream, and rotates in the tidal stream. I've borrowed the Guardian's illustration here, and their article is here.

The article quotes all sorts of Dons claiming fantastic unit generation costs (£1.7 million/MW installed - better than offshore wind), and a typical THAWT (Transverse Horizontal Axis Water Turbine) comprising two units with a total capacity of 12 MW.

Apparently the technology has been tank tested, and plans are afoot for a half scale device to be sea-tested in 2009 but there's not a peep about where the money will come from.

And why have entitled this blog entry as I have? Because we know of at least one other horizontal transverse axis device out there, among the more than 60 companies we follow on the main Redfield website.

It's all go in Strangford Lough

Oceanflow Energy has just deployed a 1:10 scale "Evopod" device in Strangford Narrows, presumably a hop and skip away from MCT's SeaGen device. The Evopod is a semi-submersible, moored energy converter which floats and yaws to optimise turbine alignment with tidal flow.

This company's been below the radar a bit, but seems to be making good technical progress. It's leading light is Graham Mackie, last seen as Technical Director at Wavegen, and founder of renewable energy consultancy Overberg (which has now morphed into Oceanflow.

Looking at Oceanflow's website, it appears that the plan is to develop a 1.5 MW evopod design.

MCT exports power to the Grid

MCT has now joined the exclusive club of marine renewables developers who have exported power to the Grid. See their press release here.

The exciting and different thing about MCT's news, relative to earlier announcements from OpenHydro, WaveGen's Limpet, Ponte de Archimedes and a few others, is that the Sea Gen is a commercially sized device, with 1.2 MW installed capacity. Its competitors at this stage are in the hundreds of kW range, so this is a different level of achievement.

Well done MCT!

River power - time for some sums

Just back from Budapest, where the Danube transects the city in a stately curve. It seems to run at a reasonable walking pace (this in June - faster in March/April, I'll bet), and must contain a fair slug of energy available for capture. Of course, this is exactly what Verdant are doing in New York at the moment.

The difference here is that Budapest has lots of lovely bridges, which could potentially act as foundations for tidal turbines (as Southampton University demonstrated at a small scale on Yarmouth Pier).

What the world needs now is some calculations on the possible power available from the Danube in Budapest. And once you've covered the Danube, there's the Rhine, the Rhone, the Volga, the Thames....

Tidal power into the Grid

Congratulations to OpenHydro, who have achieved the first power export into the National Grid from a tidal turbine (at least that Redfield is aware of). The Telegraph's coverage of the story is here.

They've narrowly beaten Marine Current Turbines, who are installing and commissioning their device in Strangford Lough at the moment.

Verdant Power - virtual tour of the RITE project

It's not every day that the Pope has any impact on the marine renewables industry. But he did yesterday, as the security arrangements for his talk to the United Nations in New York made it logistically difficult for the delegates at the Global Marine Renewable Energy Conference to get from the conference hotel (Broadway and 44th St) to Roosevelt Island (aerial tram from 59th Street and 2nd Avenue).

So Verdant brought a virtual tour of the facility to the hotel, and very impressive it was too.

For me, the key points were

• Verdant has generated nearly 50 MWh over 7,000 turbine-hours


• The technology is on version 5 - this isn't an easy or quick process


• The units are currently rated at 35 kW, and achieve a capacity factor in a tidal setting of c. 30%, but maybe 70%in run-of-river


• Verdant was extremely coy about costings


• Verdant has spent "as much" on environmental studies (lots of money on fish monitoring) as on the technology

I'm very impressed with the step-wise Verdant approach (reminiscent of the Pelamis staged development approach) and by the progress achieved.

Pulse Generation - pulls the rabbit out of the hat

John Hutton, the BERR Minister today announced that it has granted planning permission for a £2 million 150 kW (yes, kW) device in the Humber.

This project has been in the offing for a couple of years. The Pulse Generation website talks about hoping to install a prototype in 2007, and the magical £878,000 BERR grant is mentioned even then. Clearly getting through the planning process has taken longer than Pulse had hoped.

On the upside, the technology is a novel reciprocating hydrofoil device (imagine two of the Engineering Business's Stingrays back to back) but with the generator above the waterline. The site looks interesting too, with a sheltered wave climate and probably quite nicely bi-directional flow.

So the population of devices in the water looks like it's getting larger again.

Islay community steps up for tidal

According to report in the Guardian (not dated 1st April, before you ask), the good folks of Islay are planning to install commercial scale tidal power (to go with the LIMPET wave device).

A look at the consultation document (on the Islay Energy Trust website) shows that the first £750,000 will be spent over the next three years as follows:

• Phase 1 Consultation


• Phase 2 Pre-feasibility


• Phase 3 Feasibility


• Phase 4 Consents

Impressively, the document includes a list as long as your arm of people who the Islay Energy Trust hopes might be convinced to pay for various elements of this work. This document goes on to say that the installed cost of the turbines will be £1.4 million/MW - £3 million/MW and aiming for a target electricity cost of 8.5p/kWh.

These figures would certainly offer a commercial return, but I don't think anyone could achieve these costs yet. So the project is relying on the technology advancing to meet the island's need, and there are plenty of companies seeking to develop their concepts to this point.

The document says that no choices have been made as to the technology to be deployed, so it would seem that the door is open for all developers!

Verdant Power - pluses and minuses

In an earlier post, I promised to write more about my recent visit to Verdant Power...but first, don't let the picture fool you - there's a 19 hour non-slack period in this stretch of water, running at up to 3 m/s.

On the plus side:

• Verdant's got kit in the water (at least I think it was in the water, the East River's a bit murky)


• Verdant has made real progress with the technology, through umpteen refinements


• It's got further development plans, both in the East River and elsewhere


• The design is simple, with relatively few things to go wrong, and may be scalable


• The site is fantastic, with well-behaved bi-directional flow at up to 3 m/s, within a 4-iron of the United Nations building (well, one of Tiger Woods' 4-irons), and better still a short taxi ride from Wall Street


• The company's already raised some significant finance (exploiting that taxi ride from Wall St)

On the "still to do" side:

• Installation is still difficult and expensive


• Labour costs in New York are high


• Reliability is still unproven, despite time in the water (due in part to the fast technology iterations)
  
• Revenue support mechanisms in the US are not as clear as in the UK

On balance, I was very impressed with the company's progress, technology and concept. There's still a fair way to go, but it seems to me that there could well be commercial applications for the technology, particularly in more accessible run-of-river style applications.

In summary, nice one Verdant!

Newsflash - MCT installs in Strangford Lough

Congratulations to MCT for getting into Strangford Lough. It's well known that the installation has been the victim of a number of spanners in the works, so a big hand is due. We'll be keenly interested to see how commissioning goes, and hope that MCT is successfully powering those thousand local homes in short order.

The Guardian has covered the story pretty thoroughly here.

Meanwhile, in the US...

From this unprepossessing container, Verdant Power is running a 6 turbine, 200 kW installation of tidal turbines in the East River of New York.

Verdant has had devices in the water since 2006, and is now on the fourth iteration of its technology.

A simple-looking self-yawing downstream three bladed turbine (see second picture)

operates in this fast flowing branch of the East River (peak stream speed up to 3.1 m/s. I'll be writing more about this interesting technology when I'm back in the office on Monday.

Have a great weekend!

Lunar Energy £500 million project!

Wow! Lunar Energy has announced a £500 million contract in South Korea to build a 300 turbine tidal farm.

The press release, also on Lunar's website, says that the project will involve 300 1MW turbines, implying a cost per MW of £1.67 - better than anything else we've seen by some margin!

It seems amazing that this contract has been landed without the technology being proven in the water at full scale yet, and we're also not clear how Lunar will deliver for this price. You can bet on much of the fabrication taking place in Korean shipyards, though.

I hope it all works out - it would be a fantastic boost for the tidal energy industry, but it's a long time to 2015 when the turbines are expected to be operational.

Lunar's got a fabulous visualisation here...

Turnberry conference

Just back from the Turnberry Infrastructure Journal conference. The photo was taken from my hotel room and shows the snow on Arran's Goat Fell this morning. Lovely.

Lots of interesting presentations and people to meet - developers, manufacturers, funds, but (shockingly) nobody from Government (except the European Commission).

Eddie O'Connor wasn't short of opinions, and when you've just sold a £1 billion business which you've built over seven years, you've got a right to be heard!

Lots of infrastructure funds were there, showing a real interest in renewables of all kinds, although a real warning shot to the UK industry that clarity of incentive was vital to attracting internationally mobile capital.

Lots of reminders, too, about how much additional renewables capacity is going to be required to meet the 15% of all energy from renewables targets. Roughly 40-45% of electricity from renewables would do the trick (cue Eddie on the need for an offshore SuperGrid).

One last thought: Chinese demand growth is equivalent to a new Germany in demand each year. Astonishing, but what a market opportunity.