Warm, wet weather leads to excess hydropower


The organization that sells hydro-electric power to Ketchikan, Wrangell and Petersburg finds itself in an unusual situation this year – plenty of electricity to sell and a decreasing demand from customers in the three Southeast communities. A warm, wet winter and lower oil prices are factors.

The Southeast Alaska Power Agency owns the Tyee Lake power plant near Wrangell and the Swan Lake plant near Ketchikan, along with transmission lines that can send electricity from those plants to the three communities.

SEAPA’s director of special projects Eric Wolfe told that agency’s board of directors this month that demand for hydro power this year is well under capacity.

“We have way, way, way more resources than load,” he said. “This morning, we had the lowest load ever, below the range of the existing control system, 4 megawatts. We had less than 25 percent of the capacity of one machine as our total deliveries this morning.”

SEAPA has been spilling water out of its plant at Tyee Lake and even turning off those turbines for periods of time in an attempt to draw down the lake level at Swan Lake.

CEO Trey Acteson explained the warm wet winter has meant a lower demand for power.

“So warmer, loads are lower. Fish processing may be a little bit lower too. We haven’t seen that pick up much this year,” he said.

With lakes full around the region, Petersburg and Ketchikan can rely more on locally owned hydro plants, before buying power from SEAPA.

Board member and Wrangell electrical superintendent Clay Hammer noted another factor.

“Speaking just strictly from Wrangell’s standpoint, I know the cost of fuel dropping has really impacted our sales,” he said. “Our big municipal boilers, all the ones that can, have all jumped ship and all gone back to oil. So I know city wide, that has impacted our revenues.”

It wasn’t that long ago that SEAPA was encouraging conservation and looking into potential new electrical sources to add to its system to keep up with a growing demand. In an effort to increase capacity, the organization this spring started a multi-million dollar project to raise the lake level at Swan Lake.

Acteson reminded the board that the situation can swing back the other way rapidly.

“Three years ago, I think, four years ago, Andy, I think Ketchikan burned almost three million bucks in diesel,” he said. “So things can switch change really fast the other way. So I always have that in the back of my head that we could be sitting here a couple years from now saying we need to build another hydro project. So always something to keep in mind.”

The three communities have backup diesel generators for when the system is down or if there’s not enough hydro power to sell.

That’s not the case this year. In fact, SEAPA is leasing a piece of equipment called a load bank to use some of the output from Swan Lake and keep the lake level low there while construction is underway.

Board members heard that SEAPA is expecting a drop in revenue in the upcoming year because of decreased power sales. Board member Joe Nelson of Petersburg wanted to look into ways to reverse that trend.

“I’m looking for any way to increase our system load whether that means going to existing customers and deal with them with potentially special rates to do certain things so they don’t switch back to oil for instance,” he said. “Go out to the new marijuana growers and maybe get them a special rate, you know, be creative. Because we can’t just continue to spill the kind of water we’re spilling and sit idly by. We gotta be proactive.”

Others on the board urged caution with the surplus. Here’s Clay Hammer of Wrangell.

“If we go out and we find new load that’s all well and good, but then if weather and fuel prices all go back to normal then we may be stuck in the situation where we’re having to raise rates to add more capacity to the system potentially. I don’t know. This situation we’re in may be temporary,” he said.

SEAPA is not raising rates for the upcoming year. The board approved a wholesale power rate of 6.8 cents a kilowatt hour for power sold to the utilities in the three towns. That rate hasn’t changed in 18 years.

The board also approved a rebate totaling $800.000 for this past year’s power sales. That will be divvied up between the three communities based on their power purchases, and essentially lowers last year’s power rate to around 6.3 cents a kilowatt hour.

Variable speed Pumped Storage Hydro Plants offer a new era of smarter energy management


The EU-funded ESTORAGE project has presented a range of options for increasing energy storage capacity across Europe, whilst also building flexibility into grids to better integrate renewables.

The project recently made some of its first results public, identifying an impressive 2291 GWh of energy storage capacity realisable through Pumped Storage Hydro Plants (PSPs) across existing development-ready sites. This is more than seven times the currently installed PSP capacity across Europe.

The sites located are across the EU-15, along with Norway and Switzerland. Southern Norway alone was found to have 54 % of the study’s total feasible pumped storage capacity with 1242 GWh. The Alps were found to have 13 % or 303 GWh across Austria, Italy, France and Switzerland, with 9 GWh in the German Alps. 5 % of the total potential capacity in the study area was found in the Pyrenees in France and Spain with 118 GWh.

Generating electricity by transferring water between reservoirs at different elevations is posited as being the most cost-effective and flexible means for GWh scale storage of electricity. PSPs are ideally suited to respond to frequent changes between electricity shortages and surpluses by generating or absorbing excess as required; with modern systems able to start the pumps or turbines from standstill in just 30 seconds.

Potential locations for new PSPs were identified in the study via a Geographic Information System (GIS) model which utilised high-level non-country/region specific selection and only looked at existing water body pairs, due to the cost advantage of connecting existing water bodies rather than building new reservoirs. These locations were further scrutinised by national experts against specific country/regional criteria, resulting in a list of potential sites ranked with their total theoretical and realisable storage potential.

Addressing the challenge of integrating renewables

Whilst renewables, such as wind and solar, represent a growing share of the world’s power output, their unpredictability weakens overall grid stability. The challenge for integrating renewables into the grid is their intermittent nature coupled with the problem of storing surplus which can be used during periods of peak demand.
However, whilst PSPs can allow more cost-effective load balancing flexibility than traditional plants such as nuclear or coal powered, conventional PSPs are also limited by only being able to regulate power in generation mode. The ESTORAGE Project is looking at the technical and economic feasibility of upgrading an existing fixed speed PSP to variable speed technology, bringing flexibility also to the pumping mode.

Here speed is varied through a frequency converter with a change in the discharge/power. With fixed speed there is only one operating point for a given head and so in effect they have limited operational flexibility, with pumps either at full power or switched off. Variable speed technology, already several years in use, particularly in Japan, caters well for the fast growth in renewable sources of power, compensating for fluctuations.

The path to smarter European energy management

The EU electricity grid will have to undergo unprecedented changes in capacity to meet increasing demand; and in ability to integrate renewables to meet climate change targets. Indeed, the EU’s Strategic Energy Technology Plan (SET) outlines the vision of wind power contributing up to 20 %, and solar power up to 15 % of the EU’s total electricity supply by 2020.
The ESTORAGE approach to retro-fitting PSPs avoids the costs associated with constructing new PSPs along with the eight to 10 years’ development time required. This advantage is especially significant due to the project’s ambition to develop solutions that could upgrade 75 % of European pumped hydro storage to variable speed. It has been estimated that up to 10 GW of additional regulation capability can be achieved through significant upgrade and this with no environmental impact.

The project, due to finish next year, is also looking at supplementary systems such as upgrading IT infrastructure for a real-time flexible system management across national systems. Additionally, the project will establish a viable business model that enables EU-wide deployment by investigating current gaps and barriers to flexible energy technologies in the market and regulatory regimes.

Micro-hydropower: Going with the flow


Increasing numbers of Wallowa County landowners are looking in to the potential of micro-hydropower.

“There is a lot of water coming out of the mountains; being able to harvest that energy in a low-impact way offers a real benefit to the community in terms of landowner bottom line, county resilience and sustainable natural resource utilization,” said Kyle Petrocine, renewable energy coordinator at Wallowa Resources.

Even small sources of flowing water — ditches, pipelines and municipal delivery systems — can work for micro-hydropower if they have sufficient flow and head. Flow is a measure of how much water comes through the intake, while head refers to the vertical distance between the water intake and the turbine.

In a micro-hydropower system, water spins turbines attached to generators to produce less than 100 kilowatts of energy. The projects are low-impact, maximize the use of local water for renewable energy, and can substantially offset electricity costs.

Irrigation systems are one good point of entry into micro-hydropower because the water is free of fish. Channeling irrigation water through hydroelectric generators makes double use of it, and mountainous terrain means there are many candidates for project sites thanks to gravity flow.

“It is great to use a renewable resource in a non‐consumptive way,” said Wallowa farmer Vern Spaur, who installed a hydroelectric generator in conjunction with his irrigation system three years ago and is now putting in a second micro-hydro project.

Feasibility studies are underway on four local irrigation systems and several individual project sites throughout the county, while a handful of projects have reached the design and engineering phase.

The irrigation system feasibility studies are being run by Wallowa Resources as part of the Irrigation Modernization Campaign, which aims to achieve optimal irrigation efficiency through partnerships. Increased efficiency means meeting the needs of the farmer with less water loss, while also leaving more water in stream. Additional aims of the project include agricultural resilience, rural economic development and environmental enhancement.

Hydropower is good for ecology and economy


Sitting on a tributary of China’s Yangtze River, Gangkouwan hydropower station does more than generate electricity.

The facility’s reservoir protects 36,600 hectares of farmland, towns, villages and roads from major floods.

Water flow is managed to ensure crops are irrigated and in line with the reproduction cycle of fish downstream.

The power station blends in well with lush plantations nearby, clean running water underneath and the picturesque mountain ridges on both sides.

Hydropower generating facilities along the Yangtze are undergoing majors overhauls to make them as eco-friendly as Gangkouwan. If they cannot reduce their ecological impact, they will be shut down.

The Yangtze winds its way across China from west to east for more than 6,000 kilometers. Its 990 billion cubic meters of water has the potential to generate 1 trillion kilowatt-hours of power, or about half of the power China generates each year.

Gangkouwan hydropower station, in Xuancheng, east China’s Anhui Province, generates 100 million kWh a year. The same amount of power would require 30,000 tons coal to be burned, which would generate 60,000 tons of carbon dioxide.

“The hydropower station should not only contribute to the local economy, it should be something for the environment, too,” said Xiao Yonghui, the power station’s general manager.

It’s a cleaner source of energy compared with fossil fuel as it helps mitigate green house effects and acid rain. But environmentalists have voiced concern over the ecological impact hydropower stations have on their locality. Large hydropower projects in the upper stream of the Yangtze River have been blamed for causing droughts as they disrupt water flow. But such alternative energy will be an inevitable choice for a country facing mounting challenges to stop air pollution turning from bad to worse after decades of over-reliance on fossil fuel.

Fossil fuels

As well as helping the country wean itself off fossil fuels, these power facilities are being approved and constructed amid an ongoing infrastructure boom used by the government as a backstop for slowing economic growth.

Officials are well aware of the problems with hydropower development in the past. Some facilities have sucked downstream rivers dry and displaced residents.

The State Council said last year that hydropower projects should be designed, constructed and operated with the local environment and communities in mind.

“We have dismantled over 100 small hydropower stations over the past two years and these sites are now farmland,” said Yang Youzhi, a local official responsible for managing hydropower works in Anhui.

Other facilities will get a boost in power generation capacity to make up for capacity lost due to the dismantling of old stations. They also need to adjust water flow in consideration with the environment, industrial and residential water usage needs and other water-related emergencies.

The provincial government also requires authorities to take actions to resume water flow disrupted by hydropower stations. Ecological protection is also featured heavily in the authorities’ plans.

Hydropower focus for POWER-GEN Europe & Renewable Energy World Europe in Italy


Italy is the 4th largest producer of electricity from hydropower in Europe, and it plays a large role in the power generation mix in the country, alongside the country’s Alpine neighbors – Austria and Switzerland. Their mountainous regions make the perfect spot for hydropower plants to be situated. Italy’s ambition is to generate 42,000 GWh of hydropower from 17.8 GW of installed capacity by 2020 (Source: International Hydropower Association).
This forms the perfect backdrop to the special Hydropower Day featuring in this year’s POWER-GEN Europe & Renewable Energy World Europe, which will take place in Milan, Italy, on June 21-23.
The conference is taking place under the patronage of the Italian Ministry of Economic Development, with the dedicated focus on hydropower being proudly supported by HydroWorld.com. Building on the legacy of PennWell’s landmark event HydroVision International, held in the USA annually, hydropower will be a running theme at the POWER-GEN Europe & Renewable Energy World Europe multi-track conference. Particular emphasis will be placed on storage, including pumped storage hydroelectricity.
Thursday, June 23, has been designated Hydropower Day at POWER-GEN Europe & Renewable Energy World Europe. The conference aims to present water power in context within the overall changing power generation market in Europe and will try to address overarching themes and questions, such as: Where is hydro fitting in the energy “cloud”? What can hydro contribute in this changing market? How could its role be enhanced? Where is European energy policy headed regarding hydroelectric power and marine energy, and what threats are out there?

Hydropower in Italy – The Facts
· 67% of energy produced by renewable sources comes from hydro
· Italy is the 4th largest hydro producing country in Europe
· 18,092 MW installed hydropower capacity
· 45 TWh annual average hydroelectric power consumption
· 16.6% hydro’s contribution to total gross electricity production
The conference program has been devised by an expert panel of hydropower professionals from such companies as Verbund, European Association for Storage of Energy, South Tyrol Energy Association, ABB, Andritz Hydro, GE Renewable Energy, and Voith.

Hydropower key to Nepal’s growth, trade with India’


Hydropower is Nepal’s key to development and the country has an economically-viable potential of 40,000 MW of generation capacity of which it can export the surplus to neighbouring South Asian countries including India, an US government funding agency has said.

Developing sustainable hydropower generation will enable Nepal to balance its supply deficit in the dry season with the revenues made through exports during the season when river flows are high, US Agency for International Development said.

USAID said Nepal heavily depends on water resources to meet its energy demands as more than 90 per cent of its total electricity generation capacity is hydropower based.

“Hydropower plays a particularly important role in Nepal’s economic future because of the scale of its potential,” the agency said, estimating that Nepal has an economically-viable potential for more than 40,000 megawatts (MW) of hydropower generation capacity.

“If such potential is realised, it could easily meet Nepal’s suppressed demand and create a surplus that could be exported to neighbouring countries in South Asia,” it said.

However, a lack of access to reliable, grid-supplied electricity is a major constraint to economic growth and an obstacle to reducing poverty, it said.

Amid growing demand, imports from India grew over the past 15 years, according to USAID. In 2014-15, imports from India accounted for 27 per cent of Nepal’s total energy supply.

Therefore, investments in hydropower can help the country address its crippling power shortage and can be best addressed by the private sector given the financial limitations of Nepal Electric Authority (NEA) and the Nepal government, it said.

As such, USAID’s five-year USD 9.9 million Nepal Hydropower Development Project supports Nepal’s efforts to expand its access to modern, quality hydropower services and realise its potential as an energy exporter in South Asia.

The project will help Nepal facilitate and encourage private sector investment in hydropower in an environmentally and socially sustainable manner, USAID said.

It will support Nepal in transforming the energy sector to create viable and efficient national power services and promote electricity trade between Nepal and India, USAID said.

According to USAID, the expected long-term results of the NHDP project include, improved economic growth, job creation, and quality of life and strengthening economic relationships between Nepal and its neighboring countries, and an improved balance of payments due to energy exports.

It is also likely to result in greater energy security due to enhanced domestic generating capacity and integration with the Indian market and a lower carbon generation future for both India and Nepal, USAID said.

Australian PM Bans Solar And Wind Power Investment

The Australian Prime Minister, Tony Abbott, seems to be hell-bent on a mission to undo the country’s past carbon emission-reduction efforts. Last Sunday, the federal government announced that not only will it ban the Clean Energy Finance Corporation (CEFC) from investing in existing wind technology, but small-scale solar power projects as well. Instead, the CEFC will focus its energies on “emerging technologies.”

The CEFC is an organization that lends funding to renewable energy projects. This new ban will be stifling not just for them, but for the future of renewable technologies since one-third of CEFC funding is in solar projects, and many of them are small-scale solar projects, including investing in household rooftop panels. It’s not as though small-scale solar projects aren’t popular either: nearly 15% of houses in Australia are equipped with solar panels.

The CEFC hasn’t sat idly after this seemingly unfair ruling. The company is getting legal advice about whether Abbott can enforce these new restrictions without having approval from the Senate. Senior lawyers have already stated that the CEFC may have legal grounds to fight the solar and wind energy ban.

Abbott defended his actions by insisting that the idea behind CEFC was only to invest in new, emerging technologies and not existing, mature technologies. “It is our policy to abolish the Clean Energy Finance Corporation because we think that if the projects stack up economically, there’s no reason why they can’t be supported in the usual way,” the Prime Minister told reporters. “But while the CEFC exists, what we believe it should be doing is investing in new and emerging technologies – certainly not existing windfarms.”

Abbott’s actions since he became Prime Minister don’t exactly bolster his claim that he wants to support renewable energy. Since 2013, when he was elected, Abbott has lowered Australia’s renewable energy targets from 41,000 gigawatt hours to 33,000 gigawatt hours, broken up Australia’s Climate Commission body and even dropped the science minister between 2013-14, essentially silencing representation from the science sector. The actions don’t match up with his statements, and it’s difficult to conclude that there isn’t some hidden agenda.

The Prime Minister of contradictions has also recently approved the opening of a huge coal mine in New South Wales that will operate until 2046. This is in light of a pressing need for Australia to source its energy needs from renewable sources instead of coal and oil. Releasing pollutants is damaging one of Australia’s most precious jewels: the Great Barrier Reef. Fishermen have recently reported seeing a 1-kilometer (over half a mile) long slick of oil. This unconfirmed incident comes as a reminder to Australia that creating a dependency on the oil and coal industry may come at a high cost.

The move away from solar technology investment seems counterintuitive since Australia is famed for being a sun haven. In fact, a solar potential map of Australia for 2013 shows that a significant portion of the country had the potential to produce more than 1500 kilowatt hours per square meter (kWh/m2) of solar-generated electricity.

Scott Ludlam, the acting Greens leader, told reporters in Perth that the Prime Minister’s agenda is to “handcuff” Australia to the coal and gas industry. “It’s a form of, I think incredibly dangerous and vindictive industrial sabotage. They’re trying to knock over the wind energy sector.”

The opposition leader, Bill Shortenadded: “The guidelines now being proposed by Mr Abbott mean that basically the only thing the CEFC could invest in is flying saucers, because anything that is any closer to development than that, Mr Abbott has conveniently saying is an established technology.”

With wind and solar power off the radar, the only options left for the CEFC are the high-risk options. The move might not spell ‘doom’ for the organization, but for them, Australia’s blazing skies just became a little bit dimmer – the Sun now a frustratingly wasted resource.

[H/T: The Guardian]

Hydroelectric Dams Drastically Reduce Biodiversity

With their green credentials, hydroelectric dams have been built at an exceptional rate all over the world. But their true environmental and ecological costs are slowly starting to unravel, as a new study shows how this renewable energy source can drive species out and dramatically reduce biodiversity.

“Hydroelectric dams have been thought to be an environmentally friendly source of renewable power – and in recent years they have been built to supply the burgeoning energy demands of emergent tropical countries,” explained Dr. Maíra Benchimol, who led the study published in PLoS One. “Our research adds evidence that forest biodiversity also pays a heavy price when large dams are built.”

The research looked at the effect the Balbina Dam in central Brazil had on the region’s wildlife. When the dam was built in the 1980s, it put a once continuous and untouched 2,360-square-kilometer (910-square-mile) area of forest underwater, killing many trees and forming an artificial archipelago of over 3,500 islands. The team of scientists from theUniversity of East Anglia spent two years surveying some of these islands, and compared them to other areas of the forest unaffected by the rising water.

The researchers placed camera traps throughout the study area to record the species and their relative abundance, and used high-resolution satellite images to assess how much forest degradation occurs on the islands. What they found was widespread loss of species living on the islands, with large mammals, birds and tortoises missing from most of the islands they looked at.

Puma caught on the camera traps. Credit: Eduardo M. Venticinque

“We found that only a few islands larger than 475 hectares still contained a diverse community of animal and bird species, which corresponds to only 0.7 per cent of all islands in the reservoir,” said Benchimol. “In addition to the effects of area reduction, most small islands succumbed to wind exposure and ephemeral fires that occurred during a severe El Niño drought in 1997-98.”

All this adds to the growing body of evidence that hydroelectric dams are not the clean, green energy once thought. Despite the dam being the world’s largest in terms of total flooded area, after all that damage and destruction, it only manages a tiny capacity of 250 megawatts. When the amount of methane that is released from the reservoir due to all the decomposing matter is taken into account, it’s calculated to produce more greenhouse gasses than even the dirtiest of coal power plants.

Despite this, Brazil is still planning on damming up more tributaries of the Amazon, flooding yet more forest and forcing indigenous peoples out of their lands. The researchers recommend that all these factors be taken into consideration when any assessment of a new dam is made, as currently they’re ignored.

Hydroelectric Generators Tap The Backwaters For Energy


For a country that receives so much rain, hydroelectric energy seems to be curiously underexploited in the UK. Just 1.5 per cent of the electricity supply is derived from water. For traditional hydropower, though, Britain has the wrong kind of water. Norway’s large array of fjords provides the country with most of its electricity needs. The gentler, smaller rivers and streams that characterise the UK’s landscape provide a poor fit for hydro. Typical hydro turbines require speeds of at least five knots to make them financially viable: most rivers flow at less than two knots. And damming rivers in the UK is an unpopular choice.

Big hydro projects using dams and tidal barriers can wreak havoc with ecosystems, causing extensive flooding, soil erosion and deforestation. Does this leave hydro up the creek? Several projects have found ways to extract the latent energy from rivers, with some based on very old ideas.

David Wilson Homes has installed a pair of hydroelectric generators in a weir on the River Wharfe next to a new 300-home estate in Otley, West Yorkshire. The 10m-long generators use the classic screw design developed by Greek inventor Archimedes – turning as the water descends through them. The builder says the screw generator will provide up to 1300MWh of energy per year.

Other techniques are based on principles discovered more recently. The Venturi-Enhanced Turbine Technology (VETT) developed by UK-based VerdErg is designed to amplify the small drops in level at fast-flowing points in a river. It does this by exploiting the principles of the Venturi effect – that a fluid forced through a constriction speeds up, causing a drop in pressure. Attached to sections of water where there is an existing low ‘head’ – or drop – such as weirs or locks, the VETT sends 80 per cent of the available water through a Venturi pump. The low-pressure environment inside the constriction is then connected with water in the remaining 20 per cent high-pressure regime to drive a turbine. The combination amplifies the effect of the existing head by two-and-a-half to three times.

VerdErg operations director Lars Boerner says the increased pressure differential created by the Venturi pump allows for more cost-effective turbines: “You can use a much smaller turbine because it sees only 20 per cent of the water. But it sees a higher pressure, which means it spins faster. It doesn’t require a gear box and it needs less civil infrastructure, so the cost comes down.”

As only 20 per cent of the water goes through a turbine, the installation of the VerdEng system should have far less effect on wildlife than the building of a dam.

VerdErg is currently aiming at the small-scale end of the generation market. A typical scheme could provide energy for tens or hundreds of households, depending on the water source available. The company has had interest from private landowners, small businesses, community energy schemes and trusts. With permits needed for each scheme, the planning process could be drawn-out but, on the upside, sources of low-head hydro are numerous. The Environment Agency has identified over 20,000 sites across England and Wales – and they are very accessible to communities and power grid locations. “It’s a very important source, a very accessible source and a very predictable source of energy,” Boerner claims.

With the vast majority of the UK’s waterways being slow-moving and flat, new technologies are seeking to exploit even this previously untapped source. One is from US firm Vortex Hydro Energy, which has developed a system to capture the energy from vortices formed in flowing water – the same energy used by fish to swim upstream.

So-called vortex-induced vibrations (VIVs) have been known of for at least 500 years. Leonardo Da Vinci observed them in the form of Aeolian tones created by wind passing across the strings of an instrument. They are responsible for destructive phenomena such as the violent shaking of bridges in heavy winds. In water they are caused when a current flows around so-called bluff bodies such as cylinders or spheres. VIVs occur when vortices form on the downstream side of the object. These vortices shed on alternate sides to create an oscillating motion. Fish exploit this phenomenon to propel them through water. 

This phenomenon interested Michael Bernitsas, a professor of marine engineering at the University of Michigan. He was intrigued that such an obvious source of energy had never been harnessed before. So in 2005 he founded Vortex Hydro Energy, a commercial venture for the technology he patented, the vortex-induced vibration for aquatic clean energy (Vivace). The Vivace consists of a three-dimensional array of horizontal cylinders that use VIVs to oscillate in a current, generating electricity by moving magnets up and down metal coils attached to their ends. The device consists of four 4m-long cylinders producing 4kW of power – enough to supply all the energy needs for two to four typical homes.

Overall, the river-scale Vivace is about the size of a room and can generate 4kW from a current of 3.2 knots. In the lab, however, Bernitsas has managed to generate energy from speeds as low as 0.8 knots. Because Vivace sits on the river bed, there are no ugly structures popping up above the surface. There is even evidence from a joint study by Harvard University and the Massachusetts Institute of Technology (MIT) that fish seem to like the device. “Fish go behind cylinders and enjoy the ride in their wake,” says Bernitsas. “They ride between vortices just as when they trail another fish in a school.”

Another device seeking to obtain energy from slow flows in flat stretches of water is a turbine system from a UK start-up, Lunagen, which claims to produce usable amounts of energy from flows as low as 1 knot. Lunagen uses a vertical-axis Savonius turbine. The design operates at high torque and so generates more energy from slower speeds. The Lunagen team has optimised the turbine to make it up to 30 per cent more efficient for river-based generation.

Lunagen’s design deploys the turbines across the entire stream, creating a blockage effect so that all of the water has to pass through the device. This, according to Lunagen founder Will Penfold, gives the turbines a tenfold increase in efficiency. A simple 2kW array consisting of two turbines could provide the energy needs of a typical UK household and units can be daisy-chained together to scale the system up. “We can gather useful levels of energy at a good levelised cost of electricity and we open up a vast resource which has previously been uneconomic,” Penfold claims.

Lunagen is looking for investors. Although the technology is basically operational, the team has yet to conduct fish trials, which will take place later this year. Despite using turbines to block the river, Penfold says the design of the turbines plus the ability to space them at different intervals means they can allow all sizes of wildlife, even otters, to pass through unharmed. He isn’t so confident, however, of securing the backing of important stakeholders such as river preservation societies and fishing groups, who could see blocking rivers with arrays of turbines as a step too far.

The most promising market for Lunagen therefore might come from countries like India and Australia, where huge networks of irrigation channels offer a vast resource of slow-moving hydro energy. “We’ve spoken with people who run medical centres slap bang next to irrigation channels and they’re running off diesel generators,” says Penfold. “If we can take 80 per cent of the load off that diesel generator, that’s a massive benefit.”

If streams and irrigation channels aren’t slow enough, how about water that isn’t moving at all? As far back as 1852 Lord Kelvin wrote about the possibility of obtaining heat energy by cooling a fluid.  It was the same paper in which he suggested refrigeration, so it is perhaps fitting that an industrial refrigeration company is now at the cutting edge of manufacturing Kelvin’s so-called ‘heat engines’. Star Renewable Energy, an offshoot of Scottish company Star Refrigeration, makes water-source heat pumps using what is essentially the reverse of the refrigeration process to produce heat energy from natural sources of water.

Star Renewable Energy’s first large-scale project was to provide the district heating for an entire city. In 2009 Norwegian city Drammen began looking for a source of heating that was efficient and environmentally friendly. It settled on water-source heat pumps and Star Renewable Energy instantly stood out as it was the only company not using hydrofluorocarbons, which are greenhouse gases,  as the coolant. Instead Star Renewable proposed using ammonia, a chemical that was not only greenhouse-neutral but also proved to be 20-25 per cent more efficient than expected.

Star Renewable Energy won the contract and now provides the city’s 65,000 inhabitants with 85 per cent of their annual heating, saving 80 per cent of the district heating bill. It does this by taking the water from the nearby fjord, at 8°C, and using it to heat pressurised ammonia to 2°C, at which point it evaporates. The ammonia gas is compressed further until it reaches 110°C and used to heat the water in the city’s heating system to 90°C.

“We are taking heat out of something relatively cold,” says Star Renewable Energy’s director, Dave Pearson, “but the concept is, so long as you can make it cooler, you are taking heat away that can be used.”

Later this year Star Renewable Energy will start a similar scheme to provide district heating for the Shetland Isles. Other parts of the UK, from Inverness and Dundee to London and Bristol, have shown an interest. The potential for water-source heat pumps is clear – the Thames alone, according to Pearson, could provide the heating for half a million homes – and the UK government has produced a water source heat map indicating potential sites for such pumps. It has set a target of 4.5 million heat pumps across the country, which could help to reduce household bills by 20 per cent.

The biggest benefit, says Pearson, comes from combining water-source heat pumps with electricity from renewable sources. “There are increased cases of wind farms not running at full capacity because there’s not enough demand for electricity at the right times,” says Pearson. “When the wind blows is when you need the most heat so rather than paying wind farms not to run, we should be grabbing the electricity from them and using it for heat pumps.”

With so much untapped energy in Britain’s river systems, it perhaps raises the question of why it isn’t already being used. For Pearson it is that water-source heat pumps, like hydro, suffer from a reputation problem. “There’s a mistrust,” he says, “which means when people have heard of them, they don’t think they work.” 

Similarly, VerdErg’s Boerner believes that existing low-head hydro techniques are too small-scale to provide the kind of quick energy fix the government seeks. “Energy production for 20, 30 or 40 households is a significant number,” says Boerner. “But for government level it’s not going to have the big impact of an offshore wind farm that can probably cover 1,000 houses.”

However, as Boerner is at pains to point out, there is no magical quick fix to the world’s energy challenges, which means small-scale hydro could play an important part in a jigsaw of future solutions. “It’s vital in the long term to develop these small projects,” says Boerner. “With hydro it does all add up and that does help contribute to securing your energy supply as well as reducing emissions.”

Superhydrophobic Material Developed That Makes Water Bounce Like A Ball

Engineers from Brigham Young University (BYU) are developing extremely waterproof surfaces that they believe could dramatically improve the efficiency of both power plants and solar energy systems. These surfaces, called superhydrophobic surfaces, are extremely difficult to wet since they cause water to aggregate and form beads that sit on the surface.

If you turn to nature you can see numerous examples of naturally occurring superhydrophobic surfaces such as duck feathers, butterfly wings and lotus leaves. These surfaces efficiently repel water, causing it to clump together and form little beads because it is more attracted to itself than the surface. These surfaces have inspired many engineers in the field of biomimetics, where scientists attempt to imitate elements of nature to solve problems.

In this present study, which has been published in Physics of Fluids, engineers from BYU produced superhydrophobic surfaces by combining hydrophobic coatings with surfaces covered in either tiny posts or microscopic ridges a tenth of the size of human hair. They then tested them by examining the way that water interacts with the surface when either dropped, jetted or boiled onto them.

Image credit: BYU. Microscopic posts used to create the superhydrophobic surfaces.

Superhydrophobic coatings such as these have numerous diverse applications in industry. They can be sprayed onto clothing such as boots and jackets to make them waterproof, or circuits and grids to keep them clean. They can also be applied to the hulls of ships to prevent the growth of organisms and reduce corrosion. But lead researchers of this study, Julie Crockett and Dan Maynes, see their research being applied to increase the efficiency of energy production systems.

The majority of power plants generate energy by burning either coal or gas to produce steam that rotates a turbine. The world’s largest solar farm that opened this year in the Mojave Desert, California, produces electricity in a similar manner by using giant mirrors to direct sunlight onto boilers which also creates high-temperature steam that drives generator turbines.

Once the turbines are going, the steam produced needs to be fed back into the system to be re-used which is achieved by condensing it back into a liquid. If the condensers were manufactured with super-hydrophobic surfaces this process could be a lot more efficient. “If you have these surfaces, the fluid isn’t attracted to the condenser wall, and as soon as the steam starts condensing to a liquid, it just rolls right off,” said Crockett in a news-release. “And so you can very, very quickly and efficiently condense a lot of gas.”

According to Maynes, if these surfaces were applied to photovoltaic cells the conversion of solar energy to electricity could also be improved because it would mean that the material is kept clean.

In order to produce their superhydrophobic surfaces, the researchers etched the micro posts or ridges onto materials that were then coated with a thin layer of a hydrophobic material such as Teflon. They then used high-speed cameras to record how water interacts with the surface. They’re currently tweaking the surfaces to gain a clearer understanding of why they are so hydrophobic, for example by changing the width and angles of the ribs.

“People know about these surfaces, but why they cause droplets or jets to behave the way they do is not particularly well know,” said Crockett. “If you don’t know why the phenomena are occurring, it may or may not actually be beneficial to you.”

If you’d like to find out more, check out this YouTube video from BYU: