Give consumers the means and they will drastically reduce their electricity demands, says CIBSE past-president Terry Wyatt
When it comes to energy, that vital part of our way of living, we are in a sad situation. We are the customers, but the supply side wields control. We have brought this upon ourselves by expecting unlimited energy always to be available at the flick of a switch. The money-hungry suppliers have scant motivation to improve the system, so it is down to us to do so. One way of doing this is through a facility called dynamic demand management, DDM.
Nowhere is the need for DDM more clearly demonstrated than with the UK’s electricity supply. Here we have an industry delivering an increasingly essential product at low efficiency and seeing no need to make improvements. The old power plants, obtained at knockdown prices and long since paid for, generate a baseline supply that is cheap to make and deliver – yet the suppliers are allowed to charge the highest rate for initial units, which are the cheapest to generate (mine are charged at almost 26p, with subsequent ones 15p or less).
The more subsequent units you use the cheaper they are, so there is little motivation for us to cut demand. If bills gave us more information, such as showing power wasted by equipment on standby, and where daily peaks occur, it would help us manage and reduce demand; but a financial incentive would still be lacking.
To appreciate why action is needed you have to understand how the national grid operates. Because it must maintain its frequency at 50Hz and electricity cannot be directly stored, the grid has to be balanced continually – supply must precisely equal demand, as millions of customers switch loads on, up, down and off. To do this, National Grid (the company responsible for operating the grid) has to pay power stations to continually change their output, using response generators whose power delivery to the grid is continuously adjusted. These “spinning reserve” generators always run with reduced or dumped capacity, which produces vast amounts of CO2 emissions. On top of this, large-scale standby plant is required to meet daily and seasonal changes in demand, and to cover for plant breakdown.
The load pattern diagram overleaf (Figure 1) shows that at least 50% extra plant has to be ready to cope with daily demand changes between base load and peak load and that, overall seasonally, the difference between summer base load and winter peak means 100% extra plant and distribution facilities have to be available. Since we don’t have definite winter and summer times, the whole 100% has to be ready to run. Worse, the spinning reserve has to be up and running at all times to match our instantaneous switching. The system is kept in balance by spinning reserve plant of 3000MW capacity, helped by a declining number of large industrial users and a few rather nasty storage devices (huge, potentially dangerous, capacitors). Taxpayers hand over £80m a year to the supply side for this equipment. We pay another £800m a year for the promise of standby plant of at least 20,000MW capacity, which has to be “warm” ready for rapid deployment. What other company gets paid to have its stock in trade in place?
We absolutely cannot afford the carbon emissions from these two inefficient sources – at least 8 million tonnes a year, about 5% of the UK total. And what if that money, almost £1bn, were saved and put into finding a way to provide renewable, emissions-free electricity?
Both the costs and the emissions could be prevented through implementation of DDM across the country. The supply side cannot bring this about, even if it wished to. It can only be achieved by the demand side: that’s us. But it must be automatic and dynamic and not dependent on human intervention, otherwise it is unlikely to be done, and certainly not at the speed required.
DDM is the cheapest yet most sure and straightforward means of cutting carbon emissions, once we have insulated our roofs and draughtproofed our windows and doors. Its cost would be quickly recovered in savings on our electricity bills. If this isn’t reason enough, public commitment to mitigating climate change adds a new strand to the electricity supply problem.
Fossil-fuelled electricity generation involves high-temperature thermal processes. Even the most modern plant can only economically achieve about 50% thermal efficiency. The rest goes to waste. Power stations are often in remote locations where that waste heat cannot be put to use economically. In recognition of this, and in pursuit of carbon cuts, small combined heat and power (CHP) generating facilities are increasingly being developed for individual buildings and for communities, together with local, renewably sourced electricity.
A growing number of councils are making such provisions a requirement of planning approval. Difficulties in storing electricity encourage local facilities to seek a connection to the national grid, but any input from the demand side exacerbates the difficulty of keeping the grid in balance.
Then there is the fact that UK power lines are maintained at their peak allowable voltage – generating heat. The +10% allowable voltage gives a consequential 21% increase of wattage, which is what we pay for in our bills. When Europe standardised its electricity systems, 415/230V was chosen and the “straying” was to be restricted to +5%. However UK suppliers successfully negotiated for +10% as this saved them having to make any changes to the UK distribution system. If anyone tries to “feed-in” some locally generated renewable power, the local distribution goes over voltage, the cables get even hotter and the “clean” power goes straight to waste. Worse still, in cities the cables have to be chilled by electrically driven cooling plant.
There are signs the importance of DDM is being recognised in the UK. “About time too” must think the engineers who, in 1993, demonstrated DDM’s efficacy with the Celect system. Developed in Cheshire by EA Technology, it was trialled and proven with a voluntary scheme then ditched on privatisation of the electricity industry.
Recent developments in controls equipment have extended the scope, ease and affordability of DDM. The US has been at the forefront of the management revolution. It started in California and now most local public utilities have demand response programmes. These offer customers substantial price reductions in return for agreement to restrict demand at peak times. Householders save money not only from reduced consumption but also from the incentivising lower tariff. The potential impact on load profile was well illustrated when on 15 August, 2007, some 50% of major customers in New York state agreed to limit demand by restricting air-conditioning use and allowing indoor temperatures to rise to upper set-points. Unlike the previous day, the maximum available capacity was not approached and there was 7000MW, or 25%, spare capacity.
The UK does not have similar large air-conditioning loads, but Figure 2 gives an indication of the changes that could be achieved by desynchronising demands. DDM could reduce UK winter capacity requirements from 45GW to 37GW and standby plant could be cut from 15GW to 5GW. Summer capacity could fall from 30GW to 25GW, with the standby requirement down from 10GW to 3GW.
DDM can be implemented far more speedily than power stations can be built, and the funds saved could help replace old, failing plant with renewable sources of energy. The EU has done several studies into the best methods for the introduction of DDM, and last year Italy launched a scheme for 30 million DDM facilities such as “smart meters” that enable users to minimize their peak demand, plus automatic “frequency response” adjustment of demand, to be installed in homes free of charge.
The ¤2.1bn cost was calculated to be recoverable from efficiency improvements in less than five years. Such activity has helped to lower the cost of equipment by factors of 10, down to £50-£100 for electrical load profile management and less than £10 for frequency responsive controls.
The EU is looking into the possibility of a continent-wide electricity grid. This could utilise concentrated solar power in Spain and North Africa; wind, waves and tides in maritime regions; and biofuels and carbon capture and storage everywhere. The fundamental prerequisite for this ambitious scheme is EU-wide DDM.
In the UK, the Department for Business, Enterprise & Regulatory Reform (BERR) received an enthusiastic report on DDM from the Centre for Renewable Energy Systems Technology (CREST) at Loughborough University in 2007. BERR promised to set up a trial of 30,000 installations and to report back before the end of 2008 but has yet to do so. Much support and pressure for implementation of DDM in UK has come from Dynamic Demand (www.dynamicdemand.co.uk), a not-for-profit group. Several organisations have also invested heavily in the technology and some have bespoke schemes under way.
But no progress has been made on the financial incentives necessary for DDM, in the form of more equitable tariffs, nor on any legislation. It is essential for the UK’s antiquated electricity tariffs to be changed if progress is to be made in transforming the electricity industry into an efficient, effective facility worthy of this 21st century. No government is likely to take on the industry companies, but surely the industry regulator should press for change? Most service providers – for telephones, broadband, television, or insurance – give us options. Under a DDM-friendly tariff, we could get a better price by choosing to keep our electricity demand inside particular bands, accepting heavy penalties if we stray outside, and agreeing to ensure the instantaneous balancing of our demands by frequency responsive switching.
Or we could choose to stay on a “full-demand” supply and accept a tariff reflecting the true cost of delivering it. There will always be, economically, a given amount of baseline electricity available. That should be shared between us all with adjustments according to social need and commercial importance. All additional demands should be provided only at the true prevailing costs of generation and delivery. The reverse is the case with the present tariff structure. Those least able to pay effectively subsidise the profligacy of those most able to. This is not justice in a democratic, caring society.
The objectives for DDM are:
- Elimination of the need for “spinning reserve” generators.
- A substantial reduction to the extensive need for standby generator and distribution facilities.
- Enable a worthwhile connection to the grid for local, renewable sources of power.
- Improve the efficiency of electricity supply and use to cut carbon emissions and costs and reduce the need to build additional power plants.
How it works
At the heart of DDM is the means to manage automatically the demand profile of electricity – the amount required and the timing. Information obtained continuously from the supply side, on supply status and pricing, is used to adjust demand profile automatically.
Selection of which user system or apparatus is connected and/or restricted at any time follows a regime prearranged in the control software. Simultaneously, a continuous check is made of the exact supply frequency and any straying from 50Hz results in the adjustment of supply to selected user equipment.
Applying a DDM facility to a building’s systems can be eased, and benefits maximised, if the services engineer thinks ahead about how to spread demand. This may involve choosing particular system types, methods and their interconnections, so that equipment and control set-points can be readily switched and adjusted by DDM without causing discomfort or operational problems.
The DDM facility will try to minimise the prevailing total demand. For example, when a toaster is switched on the fridge freezer takes a rest, and when the kettle is turned on a heat-pump pauses until the kettle boils.
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