Articles & Case Studies

Water utilities get onboard with demand response

Posted: Monday 2nd June 2014

Closer examination of how the water industry intends to help the UK meet its legally binding commitments towards reducing CO2 emissions by 2050 is expected. Decarbonising the electricity grid and generating more energy from renewables are two ways that could help the industry meet emission reduction targets.

Ziko Abram, director and co-founder of KiWi Power discusses how demand response is helping UK water treatment works and supply pumping stations to reduce energy consumption, avoid peak tariffs, lower energy bills and reduce CO2 emissions.

Carbon commitment

The UK’s commitment towards reducing – by 2050 – greenhouse gas (GHG) emissions by at least 80% from their 1990 levels, imposes challenges for many industries. It’s thought that sewerage networks and water treatment plants will come under closer scrutiny as their carbon footprints increase proportionally as other higher polluting industries, such as power generation, transport, building and manufacturing, take positive action to reduce their carbon emissions by 2050.

The water industry accounts for around 5 million tonnes of CO2 emissions per year. In other words just 23 companies generate almost 1% of the UK’s GHG emissions.

Furthermore, water treatment plants could find themselves responsible for more than doubling emissions as tighter water regulations take effect under the EU Water Framework Directive (WFD). According to the Environment Agency, the directive is likely to lead to additional wastewater treatment (which means more energy usage) in the UK, boosting CO2 emissions by more than 110,000 tonnes a year.

Therefore, the water industry has an important role to play in helping the UK achieve its overall CO2 reduction target. As Dr. Douglas Crawford-Brown points out in the Environment Agency’s ‘A Low Carbon Water Industry in 2050’ report:

“…we all got ourselves into an escalating threat of climate change and so we can all contribute to the solution. Therefore each sector is to reduce emissions by 80% regardless of where it stands in the league table of emitters.”

In this report, six academics were asked to envisage what the water industry might look like in 2050 and and make recommendations on how to lower its carbon footprint. All of the authors concluded that in order to reduce carbon dioxide equivalent (CO2e) emissions, partnerships with suppliers and consumers were important, along with a framework of effective policy.

As part of a holistic approach recommended by the authors, the need to decarbonise the electricity network and exploit renewable energy sources were seen as essential measures.

If the volume of water requiring treatment and pumping continues to increase due to flooding caused by climate disruption, then the demand for energy is also likely to rise. One answer would be to generate greater amounts of energy using renewable technologies and feed any excess green energy back into the grid. However, there are difficulties involved when relying solely on renewable energy sources, such as solar, wind and hydro schemes. Intermittency in wind and sunlight can reduce generation capacity while upfront capital investment in renewable technologies can be difficult to secure.

Demand response and triads

One strategy that is currently allowing the water industry to tackle the problem of intermittency with renewables is electricity demand side management (EDSM), otherwise known as demand response (DR).

Demand response allows commercial and industrial sites to reduce their energy consumption during times of grid stress by temporarily turning down non-essential systems. Switching over to standby power assets, such as diesel generators, as part of a routine resilience-testing schedule is an effective way for many companies to save money and reduce the strain on the electricity network. Another option would be for water treatment plants to shift certain energy-intensive operations during times when energy prices are lower. This peak tariff avoidance strategy is referred to as triad management.

The Transmission Network Use of System (TNUoS) charges – or ‘triads’ – are the three half-hour periods that electricity demand is at its highest across the UK. Energy supply companies will charge medium-large enterprises significantly more for their electricity during these periods, which in effect penalises energy consumption during peak times. Triad charges vary depending on location as some areas of the UK, such as Scotland, have a less congested network compared to, for example, London.

At present, triad charges can amount to over £50,000 of avoidable annual energy costs and, as energy prices continue to rise, so too will TNUoS charges.

When several sites, whether they’re hotels, NHS hospitals, airports, retail distribution centres or water treatment plants all agree to participate in a demand response event, then several megawatts (MW) of combined aggregated power can, in effect, be removed from a congested electricity network at short notice. This allows grid operators to avoid bringing polluting power stations fully online in order to provide extra capacity, or prevents the need to import expensive energy from abroad.

Success in the south

If water companies can reduce pumping activities for short periods of time, or shift them to off-peak hours, they can have an immediate impact on their electricity demand without requiring any capital investment. Sembcorp Bournemouth Water (SBW) is implementing demand response to better manage its electricity demand.

SBW supplies over 140 million litres of drinking water each day to nearly half a million people from its base in Bournemouth, and has network coverage in parts of Dorset, Hampshire and Wiltshire.

Currently, SBW has three operational demand response sites, which utilise assets at water treatment works and supply pumping stations at Alderney, Stanbridge and Knapp Mill.

Demand response programmes are able to utilise standby power assets following dispatch calls from National Grid to turn down energy consumption when the grid is busy. By participating in DR, SBW is not only saving money on its energy bills, it also benefits from having a reliable contingency for back-up power in the event of a black out or grid failure.

Resilience testing

Like a car engine, generators require frequent use to keep them working efficiently and, in order to ensure emergency preparedness, should be tested at least once a month. Testing ‘off-load’ can cause poor combustion, soot formation, clogging of injector rings and unburnt fuel creating oil contamination. Fuel kept in storage for extended periods of time can lead to further deterioration and damage. Demand response allows standby generators to be tested ‘on-load’ and at full capacity, making it an ideal way to prove engine resilience and optimise performance. Generators are most valuable in DR programmes where they are able to synchronise with the mains grid supply because they can support significant site electrical loads.

Should SBW decide to respond to a DR event, operators working in the main control room are alerted as to when they need to start their local diesel generators and remove their load from the national grid. It also allows them to temporarily stop or shift scheduled pumping.

Following the initial success of DR at the three SBW sites, the company is now reviewing other potential locations having recognised the financial and operational benefits of the programme.

Tony Primmer, production manager for SBW remarked: “We continue to both review and optimise our energy use and costs as key components of operations performance. Demand response provides a mechanism to optimise pump scheduling and utilise standby generation assets whilst delivering a revenue stream back to the business.”

With no upfront costs involved in the setting up of a DR programme and availability and participation payments made through aggregators such as KiWi Power, water utility companies are beginning to recognise the ‘win-win’ situation offered by the energy reduction programme.

By participating in DR, SBW is at the forefront of implementing recommendations to help the water industry decarbonise the electricity grid, lower its carbon footprint and reduce CO2 emissions.

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