Tag: battery energy storage

Storage solutions: 3 ways energy storage can get the grid to net zero

28 February 2022

Electrification

Key points:

  • Energy storage plays a crucial role in the UK electricity system by not only providing reserve power for when demand is high but also absorbing excess power when demand is low.
  • The UK’s electricity system’s growing dependency on intermittent renewables means the amount of energy storage needed will increase to as much as 30 GW by 2050.
  • There are three different durations of energy storage needed to help balance the grid: short-term, day-to-day and long term.
  • It will take a range of technologies including batteries, pumped storage hydro and new approaches to meet the storage demands of a net zero grid.

When you turn on a lightbulb – in 10, 20, or 30 years – the same thing will happen. Electricity will light up the room. But where that electricity comes from will be different. As the country moves toward net zero emissions, low carbon and renewable power sources will become the norm. However, it’s not as simple as swapping in renewables for the fossil fuels the grid was built around.

Weather dependant sources, like wind and solar, are intermittent – meaning other sources are needed at times when there’s little wind or no sunshine to meet the country’s electricity demand. Equally as challenging to manage, however, is what to do when there’s an excess of power being generated at times of low demand.

Energy storage offers a low carbon means of delivering power at times of low supply, as well as absorbing any excess of generated power when demand is low, helping to balance and stabilise the grid. As the electricity system transforms through a range of low-carbon and renewable technologies, the amount of energy storage on the UK grid will need to expand from 3 GW of today to over 30 GW in the coming decades.

The storage solution

Even as the UK’s electricity system transforms, from fossil fuels to renewables, the way the grid operates remains primarily the same. Central to that is the principle that the supply of electricity being generated must always match the demand on a second-by-second basis.

Too little or too much power on the system can cause power outages and damage equipment. National Grid needs to be able to call on reserve power sources to meet demand when supply is low or pay to curtail renewable sources’ output when demand drops. During the summer of 2020, for example, lower demand due to Covid-19 coupled with high renewable output resulted in balancing costs 40% above expectations.

“There is a lot of offshore wind coming online in Scotland, as much as 11 GW by 2030 and a further 25 GW planned,” explains Steve Marshall, a Development Manager at Drax.

Offshore wind farm along the coast of Scotland

“It’s great because it increases the amount of renewable power on the system, but the transmission lines between Scotland and England can become saturated as much as 30-40% of the time because there is too much power.”

Electricity storage can provide a source of reserve power, as well as absorb excess electricity. These capabilities are crucial for balancing the grid and ensuring that frequency remains within a stable operating range of 50 Hertz, as well as providing other ancillary services.

Whether it’s absorbing power or delivering electricity needed to keep the grid stable, in energy storage, timing is everything.

There are three main time periods electricity storage needs to operate over:

  1. Fast-acting, short term electricity

Because electricity supply must always match demand, sudden changes mean the grid needs to respond immediately to ensure frequency and voltage remain stable, and electricity safe to use.

Batteries are considered the fastest technology for responding to a sudden spike in demand or an abrupt loss of supply.

Battery technology has evolved rapidly in recent decades as innovations like lithium-ion batteries, such as those used in electric cars, and emerging solid-state batteries become more affordable and more commonplace. This makes it more feasible to deploy large-scale installations that can absorb and store excess power from the grid.

“Batteries are good for near-instantaneous responses. It can be a matter of milliseconds for a battery to deploy power,” says Marshall. “If there’s a sudden problem with frequency or voltage, batteries can respond – it’s something that’s quite unique to them.”

The speed at which batteries can deploy and absorb electricity makes them useful grid assets. However, even very large battery setups can only discharge power for around two hours. If, for example, the wind dropped off for a long period the grid needs a longer-duration supply of stored power.

  1. Powering day-to-day changes in supply, demand, and the grid

When it comes to managing the daily variations of supply and demand the grid needs to be able to call on reserves of power for when there are unexpected changes in the weather or electricity demand from users. Pumped storage hydro power offers a low carbon way to provide huge amounts of electricity, quickly and for periods that can last as long as eight or even 24 hours.

The technology works by moving water between two reservoirs of water at different elevations. When there is demand for electricity water is released from the upper reservoir, which rushes down a series of pipes, spinning water turbines, generating electricity. However, when there is an excess of power on the electricity system the same turbines can reverse and absorb electricity to pump water from the lower to the upper reservoir, storing it there as a massive ‘water battery’.

Pumped storage hydro is a long-established technology, having been developed since the 1890s in Italy and Switzerland. In the UK today there are four pumped storage hydro power stations in Scotland and Wales, with a total capacity of 2.8 GW.

Among those is the Drax-owned Cruachan Power Station in the Scottish Highlands. The plant is made up of four generating/pumping turbines located inside Ben Cruachan between Loch Awe and an upper reservoir holding 10 million cubic metres of water.

Turbine Hall at Cruachan Power Station

Pumped hydro storage facilities can rapidly begin generating large volumes of power in as little as 30 seconds or less. The ability to switch their turbines between different modes – pump, generate, and spin mode to provide inertia to the gird without producing power – make pumped storage hydro plants versatile assets for the gird.

“How Cruachan operates depends on weather,” says Marshall. “We make as many 1000 mode changes a month, that’s how frequently Cruachan is called on by National Grid.”

As the electricity system transforms there will be a greater need for flexible energy storage like pumped storage hydro, this is why Drax is kickstarting plans to expand Cruachan Power Station, however, the specific conditions needed for such facilities can make new projects difficult and expensive.

Cruachan 2, to the east of the original power station, will add up to 600 MW in generating capacity, more than doubling the site’s total capacity to more than 1GW. By increasing the number of turbines operating at the facility it increases the range of services that the grid can call upon from the site.

  1. Long-term electricity solutions

However, storage technologies as they exist today cannot alone offer all the solutions the UK will need to achieve its net zero targets. While technologies like pumped storage can generate for the better part of a day, longer periods of unfavourable conditions for renewables will need new approaches.

In March 2021, for example, the UK experienced its longest cold and calm spell in more than a decade, with wind farms operating at just 11% of their capacity for 11 days straight, according to Electric Insights.

The shortfall in the country’s primary source of renewable power was made up for by gas power stations. But in a net zero future, such responses will only be feasible if they’re part of carbon capture and storage systems or replaced by other carbon neutral or energy storage solutions.

Generating enough power to supply an electrified future, as well as being able to take pressure off the grid and provide balancing services will require a range of technologies working in tandem over extended periods.

Interconnectors with neighbouring countries, for example, can work alongside storage solutions to shed excess power to where there is greater demand. Similarly, rather than curtailing wind or solar power, extra electricity could be used for electrolysis to produce hydrogen. Other functions may include demand side response where heavy power users are incentivised to reduce their electricity usage during peak periods helping to reduce demand.

To achieve stable, reliable, net zero electricity systems the UK needs to act now to not only replace fossil fuels with renewables but put the essential energy storage and balancing solutions in place, that means electricity is there when you turn on a lightbulb.

Charge. Recharge. The evolution of batteries

23 December 2020

Electrification

From watches to toothbrushes, mobile phones to cars, batteries are a power source for many of our everyday belongings. And while their beginnings can be traced back to the 19th century, their innovation has transformed industries, technology use and society at large today.

Energy storage systems such as pumped-hydropower have long played an important role in balancing electricity systems, but as the UK and countries around the world seek to decarbonise industries and make greater use of intermittent, renewable sources, there is a need for greater levels of storage.

While pumped-hydro storage requires the right kind of terrain, batteries can theoretically be built wherever there is the space and investment. But what actually is a battery, and how does it work?

Turning chemicals to electrical flow

Batteries are comprised of one or more cells which store chemical energy, and are able to convert that energy into electricity. In most batteries, there are three main components: an anode, cathode and electrolyte.

The anode and cathode are terminals for the flow of energy and are typically made of metal. The electrolyte is a chemical medium that sits between the terminals allowing an electrical charge to pass through. This is often a liquid, but increasingly research points to the potential to use solids and create what are known as solid-state batteries.

How a lithium ion battery works

How a lithium ion battery works

It’s only when a battery is connected to a device that it completes a circuit and chemical reactions take place that allow the flow of electrical energy from the battery to the device. But how much electrical energy a battery can dispense has always been a hurdle to using them as a power source, making rechargeable batteries an important breakthrough.

The same reaction backwards

A key element in battery development was the exploration of rechargeable cells. These have long provided mobility and reliability in small scale outputs, but are now being looked to as a source of large-scale energy storage.

Invented by physician Gaston Planté in 1859, rechargeable batteries are possible because the chemical reactions that take place are reversible. Once the initial stored charge has been depleted via chemical reaction, these reactions occur again, but this time backwards, to store a new charge.

Battery charger with AA rechargeable batteries

Battery charger with AA rechargeable batteries

Using a lead-acid system, Planté’s composition was similar to that found in rechargeable batteries used in cars and motorbikes today, although the characteristics of these cells, such as their heavy weight, meant they were not convenient for many other uses.

As a result, a journey of continuous research and optimisation to decrease the size and weight of rechargeable batteries began. This includes investigation into the alternative chemical compositions found in batteries today – nickel-metal hydride and lithium-ion to name two.

Recharging in a low-carbon energy system

Just as we have seen the size and capacity of batteries bettered throughout history, the application and optimisation of modern-day lithium-ion cells looks to continue too, powering the world’s move towards a low carbon, renewable energy future.

From electric vehicle batteries with a million mile lifespan to a 200 megawatt battery farm in South Africa, lithium-ion allows reasonably large-scale energy storage. It can also play a key role in power grid stabilisation over short durations of time such as a few hours.

Tesla gigafactory

Tesla gigafactory

For the UK to run on 100% renewable electricity sources, batteries would be imperative in complimenting other flexible renewables, such as biomass and hydropower. As a support technology, batteries can help ensure a continuous supply of electricity to homes and cities, even when cloud cover and low wind prevents other sources generating.

Conversely, charging and recharging batteries can also be used to absorb and store electricity when there is more sun and wind generation than needed, avoiding surges in electric current or wasted generation.

Changing charging

Woman charging smartphone using wireless charging pad

Alongside the advancements of battery capacity and composition, the way we use them to charge is also changing. Just as Bluetooth and Wi-Fi avoid the tethering required of wired connections, wireless charging can increase mobility and remove physical limitations.

Small-scale wireless charging is in use today. Many mobile phones, toothbrushes, smartwatches and earbuds now have wireless charging pads. These use near-field charging, meaning the device must be in close proximity to the charger to receive power.

However, efficient far-field charging is in development, with companies like Energous and Ossia developing over-the-air charging solutions for wearable tech, medical products, smart homes, and industrial equipment. This would mean devices could be powered and charged from many metres away.

The implications of this are vast, for example your devices could be charged just by entering your home or office. There could be less need for invasive surgery to change the batteries for pacemakers, neurotransmitters and other implanted medical equipment.

This type of technology could also provide passive charging for electric vehicles. The UK Department for Transport has announced a trial in Nottingham, where charging plates will be placed on parts of the town’s roads allowing electric taxis to charge while waiting briefly to pick up passengers. As charging technology and speed continues to increase, this might mean vehicles could charge wirelessly not only while parked, but when stopped at traffic lights.

3d rendered illustration of an elderly man with a pace maker

As the world shifts away from fossil fuels to renewable sources, batteries, with continued improvement in performance and capacity, will be crucial in supporting our connected lives, transport systems and electrical grids.

How to make batteries more sustainable

16 October 2020

Electrification
batteries in a recycling bucket

Batteries can be found everywhere: in our houses, in our cars and vans and even in the tech we wear. More than just being pervasive, battery technology has enabled a huge amount of technological breakthroughs – from the increasing distances electric vehicles can travel between charges, to being able to store renewable electricity for when it’s needed.

These two developments in particular – emission-free electric transport and grid-scale batteries that can power homes, businesses and cities even when energy sources are not generating – could be two key aspects in the transition to a zero carbon energy future. However, questions remain around batteries’ environmental impact.

What’s in our batteries?

The batteries we use every day are typically made from a mix of metals and chemicals such as lead and acid (as found in petrol and diesel-engine cars), or zinc, carbon, nickel and cadmium, which make up some of the batteries found in the home.

Then there’s lithium-ion. The go-to material mix for the rechargeable batteries powering mobile phones, laptops and, more recently, a high proportion of electric vehicles around the world.

The surge in the production of lithium-ion batteries over the last decade has led to an 85% price reduction, which in turn, has encouraged the use of these reliable batteries in electric vehicles and large-scale energy storage solutions. While this is a positive step in the development of rechargeable goods, it raises issues in the handling of spent batteries.

Each year around 600 million batteries are thrown away in the UK alone – even rechargeable batteries have a shelf-life. While recycling allows the safe extraction of raw materials for use in other industries and products, the majority of discarded batteries are left to rot in landfill sites. This can lead to their chemical contents leaking into the ground causing soil and water pollution.

Batteries left in soil

For batteries of any size to play a role in a sustainable future, an overhaul is needed in preventing harmful levels of battery waste. 

The battery problem

Although the number of batteries that are recycled has increased, currently the EU puts the recycling efficiency target for a lithium battery at only 50% of the total weight of the battery.

Connecting positive and negative terminals on a rechargeable lithium mobile battery

Standard recycling methods achieve this by separating and processing the plastics and wiring that make up the bulk of the battery pack, then smelting and extracting the copper, cobalt and nickel found within the cell, releasing carbon dioxide in the process. Crucially, these recycling practices do not typically recover the aluminium, lithium or any of the organic compounds within the battery, meaning that only around 32% of the battery’s materials can be reused. A lack of recycling facilities in the UK means spent batteries have traditionally been exported overseas for treatment, upping emissions even further.

It is not only spent batteries that cause a problem, the creation of them can be harmful too. For example, lithium mining can pose health hazards to miners and damage local communities and their environments.

In one area of Chile, 65% of available water is used in the production of lithium for batteries, meaning water for other uses, such as maintaining crops, must be driven in from somewhere else, impacting farmers greatly. There are also risks around contaminated water leaking into livestock and human water supplies, as well as causing soil damage and air pollution.

As a result, teams across the globe are working to make the production and recycling of batteries more efficient and eco-friendly.

Switching materials

Researchers based at Chalmers University of Technology in Sweden and the National Institute of Energy in Slovenia, are developing an aluminium-ion battery. This type of battery offers a promising alternative to lithium-ion due to the abundance of aluminium in the Earth’s crust and its ability, in principle, to carry charges better than lithium.

Disassembling the battery from an electric vehicle (EV)

The reduction in material and environmental costs that come with using aluminium over lithium might mean batteries made with it could offer more affordable, large-scale storage for renewable installations.

While more research is still needed to reduce the size and control the temperature of aluminium batteries, researchers believe they will soon enter commercial production and eventually could replace their lithium-ion predecessors.

Elsewhere, IBM Research’s Battery Lab is developing a sustainable battery solution made predominantly of materials extracted from seawater, a composition that would avoid the concerns associated with the production of lithium-ion cells.

While the exact combination of materials in not public, Battery Lab claims the new concept has outperformed its lithium-ion counterpart in energy density, efficiency, production costs and charging time. 

Making good of the old

Along with advancements in battery development, new recycling methods are also reducing the environmental impact of batteries.

German company, Duesenfeld, is innovating the recycling of lithium-ion batteries used in electric vehicles through an innovative new process.

Batteries are first discharged and disassembled into their constituent parts. The metals are extracted with a water-based solution, the liquid chemicals evaporated and condensed, and the dry materials crushed and separated, ready for reuse. Importantly, Duesenfeld’s method avoids incineration, reducing the carbon footprint of lithium-ion battery recycling by 40% and enabling over 90% of the batteries’ materials to be salvaged and reused in new batteries.

Fortum, a Finnish energy company, is exploring a similar process, with the potential to recycle more than 80% of battery materials, including cobalt, manganese and nickel.

This year Fortum signed a deal with German chemical company BASF and Russian mining and smelting firm Nornickel to develop a renewable-powered, electric vehicle battery recycling cluster in Finland. The aim is to create a ‘closed-loop’ battery production and recycling system, meaning materials from recycled batteries would be used to make new batteries.

While it is clear there is a long way to go in reducing the environmental impact of battery production and recycling, continued development of both batteries and technology can pave a path for a cleaner, safer, battery-powered, zero carbon future.

Electric vehicle battery pack

EV fast facts from Electric Insights:

  • Electric vehicles (EVs) on roads in Great Britain – including EV vans – emit on average just one quarter the carbon dioxide (CO2) of conventional petrol and diesel vehicles
  • If the carbon emitted in making their battery is included, this rises to only half the CO2 of a conventional vehicle
  • EVs bought last year could be emitting just a tenth that of a petrol car in four years’ time, as the electricity system continues to decarbonise

The 182-year history of electric vehicles

29 April 2020

Electrification

If the rapid rise of electric vehicles (EVs) over the last decade tells us anything it’s this: the future of transport is electric. But while EVs may be the fast-growing future of mobility, their beginnings stretch right back to the days of the first automobiles.

Today we associate EVs with hallmark tech innovators like Elon Musk and his Teslas, but the original electric vehicle had a much more humble beginning – in a 19th century workshop in Scotland, owned by a chemist named Robert Davidson.

Realising the potential of electric transport

'Barking up the wrong (electric motor) tree' by B. Bowers, Proceedings of the IEEE 2004

‘Barking up the wrong (electric motor) tree’ by B. Bowers, Proceedings of the IEEE 2004

Using electricity to power transport has long made sense as a means of moving around quickly and efficiently. Robert Davidson of Aberdeen understood this as early as 1837, when he created his first electric motor – powered by zinc-acid batteries.

While Davidson was a chemist, he had a fascination with tinkering and engineering. Two years after creating his first motor, he invited visitors to his ‘Electromagnetic Exhibition’ where they could see a fully visualised electric model train capable of carrying two people at a time. He would go on to develop a prototype dubbed the ‘Galvani’, which he tested on the Edinburgh-Glasgow Railway in 1842, reaching a maximum speed of 4 miles per hour.

Davidson overcame the hurdle of finding a battery strong enough to power a full-sized train by using liquid chemical batteries rather than solid ones. However, when they ran flat, the chemicals had to be completely replaced. There was a further spanner in the works when railway workers destroyed his locomotive fearing the move toward electric vehicles would put them out of a job.

It wasn’t until 1884 that the first production-standard electric car capable of being reproduced and sold to the public was unveiled. The man behind this was Thomas Parker, who was also responsible for electrifying the London Underground.

His car was born out of a desire to minimise smoke and pollution in London, a purpose which still rings true over 135 years later. More practical uses for these vehicles sprung from Parker’s initial foray, with electric wagons being instituted in mines so their motors wouldn’t pollute the air.

The Parker Electric, 1890, invented by Thomas Parker

The Parker Electric, 1890, invented by Thomas Parker

The Golden Age

Mercedes-Electrique advertisement from 1907 © Daimler AG.

Mercedes-Electrique advertisement from 1907 © Daimler AG.

EVs came into their own in the early 1900s, when popularity in Europe and America surged. Unlike gasoline (at the time, petrol was the primary fuel source) EVs did not produce a strong stifling smell, nor did they require gear changes or manual effort to start them, such as using a hand crank.

It was during this period that many well-known car manufacturing names began experimenting with electricity. Ferdinand Porsche – founder of the eponymous sports car –produced an electric vehicle called ‘P1’ in 1898, before creating the world’s first hybrid offering, which was powered by both electricity and a combustion engine. Mercedes-Benz also offered up an electric model called the Mercedes Mixte, in 1906. This car was adopted as a taxi in cities and was even developed into a race car in 1907.

No longer seen as a threat to the existing coal-powered transport, the EVs of the time were limited by the charge in their batteries, but experienced a vogue as ‘city cars’ for the rich who wanted to travel short distances in style. Sales peaked in the early 1900s, when roughly one-third of all cars on US roads were electric.

But EVs first Golden Age came to an abrupt end in the 1920s with the arrival of the man whose name would become synonymous with car manufacturing the world over: Henry Ford.

The rise of petrol

When Ford’s Model T parked on the scene, it brought with it affordable, mass produced petrol-powered transport – EV popularity quickly began its descent. Their limited battery capacities had become a downside as road networks expanded, and the discovery of more petroleum deposits meant that gasoline was more readily available and cheaper than recharging batteries.

Electric milk float in Barnet, London, 1970

One of the only EVs that survived the next few decades was the quintessentially British milk float, which made up the majority of global EVs for most of the 20th century. Away from milk rounds and golf carts, the entire electric automobile industry went silent and the technology stagnated – it looked like gasoline was here to stay.

That was, until a very special electric car took a spin in outer space.

The moon is the limit

In the summer of 1971, the world was glued to TV sets as the Apollo 15 mission to the moon unfolded, featuring a special guest – the new Lunar Roving Vehicle, which ran on battery power. There are currently three rovers parked on the moon, and their continued evolution helped renew interest in electric powered vehicles throughout the 1960s and 70s. It led to a few new battery-powered concept cars appearing, manufactured by General Motors.

Apollo programme lunar rover

Apollo programme lunar rover

Now powered by lithium or nickel-cadmium batteries, these cars provided a viable option for those concerned about the economic fluctuations of the oil and gas industries, with electricity not as exposed to market changes.

The pace of EV innovation picked up after the development of the lithium-ion battery, which significantly extended life and power output, opening the potential for electric vehicles to become more than just short distance city cars.

These cars weren’t produced en masse until the 2000s, after more than three decades of the global environmental movement and its influence over public policy.

As the technology caught up with an ambition to find a practical alternative to fossil fuel powered transport, the EV entered its second golden age.

Tesla driving towards onshore wind farm

Tesla driving towards onshore wind farm

Where are we now?

Today there are over 273,000 electric cars on Britain’s roads, but this is set to grow quickly and significantly. By 2025 it’s estimated there will be 1 million EVs on UK roads – by 2040 there could be as many as 11 million.

Most mainstream car producers are now racing to take the lead in the EV market, from the headline grabbing antics of Tesla to the petrol-powered stalwarts of Volkswagen, Nissan and even Ford. And it’s not just the personal vehicle industry where electricity is racing ahead as a fuel source. Everything from inner-city scooters to the rapidly-evolving aviation industry are being electrified – the first electric passenger jet could be ready for take-off as soon as 2027.

Powering the way that we travel has become one of the most important conversations around the future of transport – and taking a look into the past suggests that this time electric vehicles are here to stay.

What is a fuel cell and how will they help power the future?

27 June 2019

Carbon capture

How do you get a drink in space? That was one of the challenges for NASA in the 1960s and 70s when its Gemini and Apollo programmes were first preparing to take humans into space.

The answer, it turned out, surprisingly lay in the electricity source of the capsules’ control modules. Primitive by today’s standard, these panels were powered by what are known as fuel cells, which combined hydrogen and oxygen to generate electricity. The by-product of this reaction is heat but also water – pure enough for astronauts to drink.

Fuel cells offered NASA a much better option than the clunky batteries and inefficient solar arrays of the 1960s, and today they still remain on the forefront of energy technology, presenting the opportunity to clean up roads, power buildings and even help to reduce and carbon dioxide (CO2) emissions from power stations.

Power through reaction

At its most basic, a fuel cell is a device that uses a fuel source to generate electricity through a series of chemical reactions.

All fuel cells consist of three segments, two catalytic electrodes – a negatively charged anode on one side and a positively charged cathode on the other, and an electrolyte separating them. In a simple fuel cell, hydrogen, the most abundant element in the universe, is pumped to one electrode and oxygen to the other. Two different reactions then occur at the interfaces between the segments which generates electricity and water.

What allows this reaction to generate electricity is the electrolyte, which selectively transports charged particles from one electrode to the other. These charged molecules link the two reactions at the cathode and anode together and allow the overall reaction to occur. When the chemicals fed into the cell react at the electrodes, it creates an electrical current that can be harnessed as a power source.

Many different kinds of chemicals can be used in a fuel cell, such as natural gas or propane instead of hydrogen. A fuel cell is usually named based on the electrolyte used. Different electrolytes selectively transport different molecules across. The catalysts at either side are specialised to ensure that the correct reactions can occur at a fast enough rate.

For the Apollo missions, for example, NASA used alkaline fuel cells with potassium hydroxide electrolytes, but other types such as phosphoric acids, molten carbonates, or even solid ceramic electrolytes also exist.

The by-products to come out of a fuel cell all depend on what goes into it, however, their ability to generate electricity while creating few emissions, means they could have a key role to play in decarbonisation.

Fuel cells as a battery alternative

Fuel cells, like batteries, can store potential energy (in the form of chemicals), and then quickly produce an electrical current when needed. Their key difference, however, is that while batteries will eventually run out of power and need to be recharged, fuel cells will continue to function and produce electricity so long as there is fuel being fed in.

One of the most promising uses for fuel cells as an alternative to batteries is in electric vehicles.

Rachel Grima, a Research and Innovation Engineer at Drax, explains:

“Because it’s so light, hydrogen has a lot of potential when it comes to larger vehicles, like trucks and boats. Whereas battery-powered trucks are more difficult to design because they’re so heavy.”

These vehicles can pull in oxygen from the surrounding air to react with the stored hydrogen, producing only heat and water vapour as waste products. Which – coupled with an expanding network of hydrogen fuelling stations around the UK, Europe and US – makes them a transport fuel with a potentially big future.

 

Fuel cells, in conjunction with electrolysers, can also operate as large-scale storage option. Electrolysers operate in reverse to fuel cells, using excess electricity from the grid to produce hydrogen from water and storing it until it’s needed. When there is demand for electricity, the hydrogen is released and electricity generation begins in the fuel cell.

A project on the islands of Orkney is using the excess electricity generated by local, community-owned wind turbines to power a electrolyser and store hydrogen, that can be transported to fuel cells around the archipelago.

Fuel cells’ ability to take chemicals and generate electricity is also leading to experiments at Drax for one of the most important areas in energy today: carbon capture.

Turning CO2 to power

Drax is already piloting bioenergy carbon capture and storage technologies, but fuel cells offer the unique ability to capture and use carbon while also adding another form of electricity generation to Drax Power Station.

“We’re looking at using a molten carbonate fuel cell that operates on natural gas, oxygen and CO2,” says Grima. “It’s basic chemistry that we can exploit to do carbon capture.”

The molten carbonate, a 600 degrees Celsius liquid made up of either lithium potassium or lithiumsodium carbonate sits in a ceramic matrix and functions as the electrolyte in the fuel cell. Natural gas and steam enter on one side and pass through a reformer that converts them into hydrogen and CO2.

On the other side, flue gas – the emissions (including biogenic CO2) which normally enter the atmosphere from Drax’s biomass units – is captured and fed into the cell alongside air from the atmosphere. The CO2and oxygen (O2) pass over the electrode where they form carbonate (CO32-) which is transported across the electrolyte to then react with the hydrogen (H2), creating an electrical charge.

“It’s like combining an open cycle gas turbine (OCGT) with carbon capture,” says Grima. “It has the electrical efficiency of an OCGT. But the difference is it captures CO2 from our biomass units as well as its own CO2.”

Along with capturing and using CO2, the fuel cell also reduces nitrogen oxides (NOx) emissions from the flue gas, some of which are destroyed when the O2and CO2 react at the electrode.

From the side of the cell where flue gas enters a CO2-depleted gas is released. On the other side of the cell the by-products are water and CO2.

During a government-supported front end engineering and design (FEED) study starting this spring, this CO2 will also be captured, then fed through a pipeline running from Drax Power Station into the greenhouse of a nearby salad grower. Here it will act to accelerate the growth of tomatoes.

The partnership between Drax, FuelCell Energy, P3P Partners and the Department of Business, Energy and Industrial Strategy could provide an additional opportunity for the UK’s biggest renewable power generator to deploy bioenergy carbon capture usage and storage (BECCUS) at scale in the mid 2020s.

From powering space ships in the 70s to offering greenhouse-gas free transport, fuel cells continue to advance. As low-carbon electricity sources become more important they’re set to play a bigger role yet.

Learn more about carbon capture, usage and storage in our series:

Balancing for the renewable future

6 July 2018

Power generation

It’s not news to say Great Britain’s electricity system is changing. Low carbon electricity sources are on course to go from 22% of national generation in 2010 to 58% by 2020 as installation of wind and solar systems continue to grow.

But while there has been much change in the sources fuelling electricity generation, the system itself is still adapting to this transformation.

When the national grid was first established in the 1920s, it was designed with coal and big spinning turbines in mind. It meant that just about every megawatt coming onto the system was generated by thermal power plants. As a result, the mechanisms keeping the entire system stable – from the way frequency and voltage is managed to how to start up the country after a mass black out – relied on the same technology. These ‘ancillary services’ – those that stabilise the system – are crucial to maintaining a balanced electricity system.

“Ancillary services are needed to make sure demand is met by generation, and that generation gets from one place to the next with no interruptions,” explains Ian Foy, Head of Ancillary Services at Drax. “Because what’s important is that all demand must be met instantaneously.”

In today’s power system, however, weather dependent technology like offshore wind and home solar panels are increasingly making up the country’s electricity generation. Their intermittency or variability is, in turn, impacting both the stability of the grid and how ancillary services are provided.

Running a large power system with as much as 85% intermittent generation – for example on a very windy, clear, sunny day – is thought to be achievable. It isn’t a scenario anticipated for the large island of Great Britain. But to deal with the fast-pace of change on its power system which recently managed to briefly achieve  47% wind in its fuel mix, there is a need to develop new techniques, technologies and ways of working to change how the country’s grid is balanced.

New storage tech takes on balancing services

One of the technologies that’s expected to provide an increasing amount of balancing services is grid-scale batteries. One stabilisation function offered by batteries (and other electricity storage options) is to provide reserve  at times when demand peaks or troughs. This matches electricity demand and generation.

Combined with their ability to respond quickly to changes in frequency, batteries can be a significant source of frequency response.

Batteries can also absorb and generate reactive power, which can then be deployed to push voltage up or down when it starts to creep too far from the 400kV or 275kV target (depending on the powerlines the electricity is travelling along) needed to safely move electricity around the grid.

The challenge with batteries is that the quantity of megawatt hours (MWh) required to compensate for intermittency is very large. The difference between the peak and trough on any day may be more than 20 GW for several hours (see for yourself at Electric Insights).

The significant price reductions in battery storage apply to technologies with short duration (or low volume MWhs). These are the technologies which have been developed at scale recently but will probably struggle to make up in any large quantity any shortfalls in generation resulting from prolonged periods of low intermittent generation.

A challenge currently being addressed relates to maintenance of battery state of charge. This is a consequence of battery storage having a cycle efficiency of less than 100%. This means that losses from continuous charging and recharging will have to be replenished from the available generation to avoid batteries going empty and being unavailable for grid services.

Ultra-low carbon advances

Rather than relying on batteries to provide ancillary services to support intermittent generation, technical advancements are allowing the wind and solar facilities – which are generating more and more of the country’s electricity – to do so themselves.

The traditional photovoltaic (PV) inverters found on solar arrays were initially designed to push out as much active, or real, power as possible. However, new smart PV inverters are capable of providing or absorbing reactive power when it is needed to help control voltage, as well as continuing to provide active power.

The major advantage of smart inverters is the limited equipment update required to existing solar farms to allow them to offer reactive power control. The challenge here is that PV is embedded in distribution systems and therefore reactive services they provide may not cure all the problems on the transmission system.

Similarly, existing wind installations have traditionally focused on getting the greatest amount of megawatts from the available resources, but with fewer thermal power stations on the grid, ways of balancing the system with wind turbines are also being developed.

Inertia is the force that comes from heavy spinning generators and acts as a damper on the system to limit the rate of change of frequency fluctuations. While wind turbines have massive rotating equipment, they are not connected to the grid in a way that they automatically provide inertia, however, research is exploring what’s known as ‘inertial response emulation’ that may allow wind turbines to offer faster frequency response.

This works through an algorithm that measures grid frequency and controls the power output of a wind turbine or whole farm to compensate for frequency deviations or quickly provide increases or decreases in power on the system. Inertial response emulation cannot be a complete substitute for inertia but can reduce the minimum required inertia on the system.

Even in a future where the majority of the country’s electricity comes from renewable sources, thermal generators may still be able to provide benefits to the system by running in ‘synchronous compensation’ mode i.e. producing or consuming reactive power without real power.

However, what is vitally important for the future of balancing services in Great Britain is a healthy, transparent and investable market for generators, demand side response and storage, whether connected on the transmission or distribution networks.

A market for the future grid

One of the primary needs of balancing service providers is greater transparency into how National Grid procures and pays for services. Currently, National Grid does not pay for inertia. With it becoming more important to grid stability, incentive is needed to encourage generators with the capability to provide it. Those technologies that can’t provide inertia, could be encouraged to research and develop ways they could do so in the future.

Standardising the services needed will help ensure providers deliver balancing products to the same level needed to support the grid. It would also benefit from fixed requirements and timings for such services. Bundling related products, such as reserve and frequency control, and active power and voltage management, will also offer operational and cost efficiencies to the providers.

Driving investment in balancing services for the future, ultimately, requires the availability of longer-term contracts to offer financial certainty for the providers and their investors.

 

Bridge to the future

The energy mix -- table showing services which can be provided by different power technologies

Click to view larger graphic.

For the challenges of decarbonisation to be met in a socially responsible way, Great Britain’s power system must be operated at as low a cost as possible to consumers.

With new technologies, almost anything could be possible. But operating them has to be affordable. In many cases, it may take time for costs of long duration batteries to come down – as it has with the most recent offshore wind projects to take Contracts for Difference (CfDs) and Drax’s Unit 4 coal-to-biomass conversion under the Renewables Obligation (RO) scheme.

Thermal power technologies such as gas that has proven capabilities in ancillary services markets can at least be used in a transitional period over the coming decades until a low carbon solution is developed.

Biomass will continue to be an important source of flexible power. This summer, at Drax, biomass units are helping to balance the system. It is the only low carbon option which can displace the services provided by coal or gas entirely.


Drax Power Station’s control room. Viewing on a computer? Click above and drag. On a phone or tablet – just move your device.

In the past the race to decarbonisation was largely based around building as great a renewable capacity as possible. This approach has succeeded in significantly scaling up carbon-free electricity’s role on Great Britain’s electricity network. However, for the grid to remain stable in the wake of this influx, all parties must adapt to provide the balancing services needed.

This story is part of a series on the lesser-known electricity markets within the areas of balancing services, system support services and ancillary services. Read more about black start, system inertia, frequency response, reactive power and reserve power. View a summary at The great balancing act: what it takes to keep the power grid stable and find out what lies ahead by reading Maintaining electricity grid stability during rapid decarbonisation.

Dude, where’s my autonomous car? How self-driving vehicles will impact electricity

25 April 2018

Electrification

The self-driving car is a sci-fi stalwart. The blend of familiar vehicle combined with advanced-artificial intelligence makes it a perfect symbol of a not-too-distant future which is fast approaching. But what a sci-fi movie is unlikely to show is a self-driving car pulling over for half an hour to fill its tank or recharge its batteries.

As autonomous vehicles gradually inch into our everyday life, the question of how they will be powered arises, as does whether they will be capable of refuelling or recharging without a helping human hand.

With governments around the world setting ambitious targets for the phasing out of diesel and petrol car sales, it’s safe to assume the driverless vehicles of the future will be electric.

But will they be able to charge themselves? More than that, how would a large influx of these cars coming onto our roads affect our national electricity demand and emissions?

How will driverless cars charge themselves?

Development is already well underway to bring human-free charging to the auto world with a variety of approaches being trialled:

  • Robotic charging points

The most straightforward way to enable self-driving electric vehicles (EVs) to charge themselves is through updating existing infrastructure. Adding on robotic limbs to standard charge points would be one way of removing the need for human hands. Tesla previously demonstrated a porotype of a snake-like arm that plugs into its vehicle’s charge points that does exactly this. 

  • Under-car charging

Easier than flailing robotic arms is the idea of charging cars from underneath a parked car. Unsurprisingly, Tesla has patented a version of the technology, too.

While building the technology into the ground adds complications, it could potentially allow cars to be charged while moving – which is exactly what one road in Sweden is doing.

The two kilometre stretch outside Stockholm features a metal track that an arm under EVs can connect to – much like a Scalextric track. The route is divided into 50-metre sections which are electrified separately as vehicles travel over them. Sweden is now planning to roll the concept out nationally.

  • Wireless charging

A step up from under-car charging, wireless technology uses inductive charging rather than physically connecting with the car, and can be installed into parking spaces, or be set into the tarmac.

The problem with this is it’s not as fast as directly connecting with the car. However, implemented at scale, entire roads could constantly charge vehicles when they need a top up.

It would mean that rather than taking EVs home and plugging them in, the city and roads themselves would charge it. But even the idea of keeping a car at home might fade as cars become increasingly autonomous.

Rethinking vehicle ownership

As more of the world’s population move to cities and they grow increasingly congested, car ownership is declining – a trend being further fueled by ridesharing services, like Uber, Lyft and Didi Chuxing in China.

And as services such as these continue to grow in popularity, it could point to a future where rather than owning self-driving cars, they will be shared among urban populations. Lyft Strategist Raj Kapoor suggested the reduced cost of maintenance of shared EVs would make rides cheap enough for the average person to ride in every day.

This could result in fewer cars on the roads as intelligent systems allow them to coordinate sharing across the population, which in turn could lead to a reduction in demand for charging. However, the more intense computing power needed in self-driving vehicles means they will each use more electricity than a standard EV.

Powering these sufficiently will depend on technology and coordination, rather than producing significantly more electricity.

Smarter cars, smarter cities, smarter electricity

Changes in car ownership could mean the total reshaping of cities. If cars don’t need to park for long periods of times on central roadsides and in garages, vehicles could instead be stored on the outskirts of cities when demand for transport is low and make their way into towns as people begin commuting.

This vision of cars, seemingly independently rolling around cities to exactly where they’re needed, depends not on a single car reacting to a single command, but to a network of data points connected to almost every aspect of a city. More than this, there’s even potential these cars could provide power as well as use it.

Vehicle-to-gird (V2G) technology means they can essentially act as batteries and return electricity to the grid when needed. A fully connected network of autonomous cars, linked to buildings, cities and entire electricity networks could be used to help meet demand on a local or national scale, helping avoid fossil fuel usage at times of stress.

While increasing EV usage will likely contribute to an increase in electricity demand, self-driving, smarter vehicles will ensure power is used at efficiently as possible and reduce the number of cars drawing electricity from the grid.

It ultimately means global investment in the charging infrastructure that will create a more connected and economical transport system, which will make widespread EV and autonomous cars a reality.