Wednesday, 17 December 2014
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The wired west

Could technology that is under trial in the US point the way for the deployment of smart grids in the UK? Stuart Nathan reports

Electricity is, literally, part of the landscape. The skeletal forms of pylons carrying high-voltage lines, marching across the countryside, are such a familiar sight that we barely register them. Yet as we derive more electricity from the landscape, in the form of wind, hydro and marine power, these most visible manifestations of the National Grid may need to change.

Electricity distribution is changing. As renewable generation gathers pace and consumers become more concerned with conserving power, the concept of the ‘smart grid’ — equipped with systems that can accept inputs from smaller power sources and tell householders how much energy they consume — will be the model for the sector’s future. In the US, major companies are teaming up with cities to test these new technologies; but for the smart grid to take off in Britain could require not just technological but also political innovation.

The whole landscape of electricity is changing, from the way it’s generated to the way it’s used, in industry and in our homes; and the infrastructure that makes up the distribution network is also going to have to change. It’s not so much the technology that’s outdated, because that has been updated regularly and steadily over the years. It’s the paradigm that underpins the way the distribution system was designed, back in the early 1960s. The old grid is on its way out. Say hello to the smart grid.

Currently, electrical distribution grids reflect the centralised, supply-led nature of power generation. Their job is to get big lumps of current from multi-megawatt power stations — generally located on the coast or in the countryside — to the consumers, who are generally in towns. On the way, the voltage is stepped down in several stages until it’s finally transformed into the familiar 230V, 50Hz AC.

But we are now starting to see changes to this system. Renewable energy sources are making bigger contributions to the grid and, of course, their contribution is set to grow considerably in coming years, with the European Union’s target of 20 per cent renewable energy by 2020. Renewable energy doesn’t contribute to the system in the same way as major power stations, however. The voltage is lower; they produce less electricity and, crucially, they don’t produce consistent amounts of energy all the time.

This is one of the reasons that electricity generation is going to have to become ‘smarter’. Rather than a one-way conveyor-belt system, the grid is going to have to accept flows of current at different voltages from different places at irregular intervals.

This represents a considerable change, but for the consumer, it will be like the rest of the grid’s workings: Invisible. In the home, however, the smart grid will be quite the opposite. The old electricity meter, hidden away in a cupboard, will go, to be replaced by a smart meter, which will show, minute by minute, precisely how much electricity the household is consuming, with a level of detail that could go down to individual appliances. This will also communicate its measurements back to the electricity supplier, allowing for billing based on actual consumption rather than estimated readings, and allowing the household to understand and regulate its use of power.

The built-in intelligence can go a step further, becoming a component of an energy-smart house. As well as sending information to the supplier, the meter can receive it. The supplier would send out information on the upcoming demand for and price of electricity, which would then be sent to appliances around the home. Ahead of a peak in demand —  which would correspond to a high price — appliances such as fridges and freezers would drop their temperature, allowing them to switch off their pumps during peak time without allowing food to spoil. Washing machines could be triggered to start and electronic gadgets to charge during off-peak periods, so they use cheaper electricity.

Moreover, if the anticipated surge in demand for plug-in electric cars takes place, these could be an integral part of the smart grid. Not only could they help level out demand by sequentially charging during off-peak periods, they could also help overcome the problem of intermittency of renewable electricity.

Central to the smart grid concept is the smart meter — the household device that tracks the use of electricity and can tell consumers exactly how much they’re using at any point, while also communicating that information back to the electricity supplier and thence to the generator. Much of the attention devoted to smart meters has focused on their usefulness in helping consumers reduce energy usage, and in accurate billing. But it’s the whole suite of possible applications that’s interesting Alan Claxton, director of organisational development at the UK Energy Network Association (ENA), who is concerned that any meters employed will be as capable as possible.

The ENA represents all the businesses concerned with transmitting energy around the country, whether it’s in the form of gas or electricity — the ‘wires and pipes’ people, to use its phrase. However, Claxton said, it’s likely that selection and deployment of smart meters will be down to individual suppliers, rather than the generation and transmission sector. ‘We’ve been working with the networks on the functionality we want to see within smart meters, because the networks’ requirements are going to be quite different from the suppliers’ requirements,’ he added.

Electricity suppliers may be able to source their own meters and roll them out to customers, but they will still have to comply with some sort of manufacturing standard, which is still to be defined. ENA is concerned that all meters should have the necessary functionality to support the sort of information that would be needed to set up a smart grid.

‘We need to have a meter that can give us an indication of no supply, latent loads covered by microgeneration, voltage levels and power quality,’ Claxton said. ‘And what we don’t want is a limited functionality that would require the replacement of a whole first generation of smart meters. We’re trying to look ahead — we need to make the system future-proof.’

Hand in hand with the functionality of the smart meters comes their communication capability. As yet, it hasn’t been decided how the meters will communicate, although it seems likely that there will a central communications hub. ‘There are a variety of options,’ Claxton said. ‘It could piggy-back onto broadband internet, for example. Another option might be a power-line carrier, which works by modulating the frequency of the alternating current signal.’

The way electricity is generated is going to have a considerable effect on how smart grids would be implemented. It might also mean that the grid is going to have to become more regional, according to Jim Watson, director of Sussex University’s energy group and a leader of the Tyndall Centre Energy Programme. ‘With the possibility of microgeneration sources coming onto the grid, and the different energy needs and supply profiles of different areas, it might be best to consider this technology on a city-by-city basis,’ he said.

This, he commented, is how smart grid trial projects in the US are being handled. There are several of these, with GE and the US operations of the National Grid being key players. National Grid, for example, announced plans in March for a pilot scheme in Worcester, Massachusetts, involving 15,000 customers, all of whom will receive a smart meter and will have the option of additional equipment such as programmable thermostats to control house heating and air conditioning. They will receive information on their energy usage via email, text message or on a PDA.

This technology doesn’t come cheap — the two-year trial will cost $57m (£34.7m). National Grid spokeswoman Marcy Reed points out that funds are available. ‘We understand that Massachusetts is interested in taking advantage of the $4.5bn of stimulus funds allocated to smart grid.’

GE is also setting up trial smart grids on a local basis, with a much bigger trial involving a million consumers in Miami. Using smart meters with a variety of readout systems, including internet and in-home display panels, an expansion of solar panel capacity to local schools and universities, open-standard communications and a fleet of 300 plug-in hybrid cars, the trial will cost $200m. For GE, the Energy Smart Miami project represents an important foot in the door; the company is heavily committed to the technology and plans to roll out similar systems across Europe; it has supplied smart meters to a trial project with Scottish and Southern Energy. ‘Smart meters are the foundation for a smart grid in Europe and a critical component to help maximise the productivity and performance we can squeeze from our infrastructure,’ commented Keith Redfearn, general manager for GE’s distribution business in Europe.

One barrier to this approach in the UK, however, is that it’s unclear whether the power to plan energy provision resides with local authorities or with the government, Jim Watson said. ‘If you’re in the situation where lots of homes have microgeneration, whether it’s wind turbines, solar panels, or a micro CHP [combined heat and power] plant in every house, then you have to get all their surplus power onto the grid. That’s a local issue, but there’s no clarity on whether a local authority can specify its own power station, for example. This sort of thing badly needs to be resolved before these systems can go ahead.’

One crucial factor in this technology is the definition of an ‘electrical appliance’, and this could have a huge bearing on the way that a future grid could work. Again, the crucial factor is renewables and their intermittent nature. Many discussions of renewable power touch upon the importance of some sort of electrical storage system that can act as a reservoir; for example, to store excess electricity from a wind farm when the wind isn’t blowing, to release it back onto the grid when the breeze dies down.

Much research has been done into what form these storage devices might take. But it appears that the answer might have been staring us in the face; or rather, parked outside our front door. Could plug-in battery-powered electric vehicles be the missing link in the smart grid?

One of the major advantages of a smart grid is that it could be used to phase the charging of battery-powered electric vehicles. Imagine a suburb with a large number of electric cars, all of which can be plugged in to recharge from their owners’ domestic electricity supply. One set of sensors in the supply system detects when the vehicle is plugged in, while the domestic communications system switches power into the battery when prices are low; that is, at night. Local intelligence ensures that all the cars within a particular area aren’t all charging at the same time, to avoid overloading the grid. The result is that, in the morning, all the cars in the area are fully charged from off-peak electricity; demand has been smoothed out; and everyone’s happy.

Extend this system a little, however, and the cars take on a dual role. Stop thinking of it as a car, and think of it instead just as a battery. Its stored power needn’t just be used to run the vehicle; it can be used for anything. As long as the vehicle is plugged in, power can be diverted out of it, onto the grid, as well as into it for charging.

Although each individual car would not be able to store a huge amount of charge, the cumulative effects could be huge. According to Jasna Tomic, new fuels programme manager for Californian low-carbon transportation advocate Calstart, if a quarter of car owners in the US switched to battery-powered electric vehicles, their storage capacity would total some 750GW — more than the country’s entire generation capability. And with the UK government’s major drive to promote the development and take-up of plug-in hybrids, the figures could well be similar here.

Systems such as these are known as vehicle-to-grid (V2G), and much of the research into them has been carried out in the US. The University of Delaware is a notable centre for V2G research, where Willett Kempton, director of the university’s Centre for Carbon-Free Power Integration, has worked with Tomic to look at the economics of V2G. ‘In the US, an average vehicle is on the road only four to five per cent of the day,’ he said. At least 90 per cent are parked, even during peak hours. If they were plugged in while stationary, fairly simple power electronics and telecoms systems would allow the utility to request power from a vehicle’s battery when demand was high and return it when demand is low. ‘Electricity from V2G is not cheap when compared with bulk electricity from large power plants,’ he commented — in general, it’s up to five times the price — ‘but it can be competitively used for ancilliary services, such as maintaining grid reliability, balancing supply and demand, and supporting the transmission of electric power from seller to purchaser.’




Readers' comments (1)

  • In the EU, why cannot electric power be traded across time zones, taking advantage of national off-peak periods?
    Surely the technology exists to create a high voltage super-grid that would level out national demands.

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