Emergency Power

Emergency Power and Reliability of Supply

The installation of an emergency power generator (e.g.. diesel generator) can provide power during a blackout.

However, simply installing an emergency power generator may not be the best solution to the problem of essential electrical equipment not being available during a blackout. Worse, it might not solve the problem which you are trying to fix.

The checklist below describes some of the other factors and solutions which should be considered.

Checklist


Determine Your Equipment and Power Needs

The first reaction may be to assume that an emergency generator is required which can operate all the equipment in a building, but this may be overkill, completely unnecessary, or unsuccessful in achieving your goal. Consider:

  • Which equipment is essential? Do you need to operate everything (and so need a standby power system with the same capacity as the recorded maximum demand? Is air-conditioning necessary. Will staff continue to work, or will only some machines or computers be left operating? Perhaps only some essential computers, cash registers, or communications equipment needs to be powered.
  • How long will that essential equipment need power for? Do you need just enough time to have a controlled shutdown of computer systems, enough time to evacuate a store, or will you need some equipment to operate continuously until power is restored?
  • How quickly must the standby power source take over? If you are thinking about a standby power system because severe voltage fluctuations are causing important equipment to malfunction (e.g.. computers rebooting, machinery “tripping” etc.) a standby generator will not solve the problem because of there will be a period with no power before the emergency generator will start.
  • If severe voltage fluctuations are the problem, these should be tackled in co-operation with your electricity distribution company. Please see our page on Electricity Supply Voltage Requirements and Problems

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Consider Uninterruptible Power Supplies

If you are trying to protect just a few items of equipment, uninterruptible power supplies may be a much better solution than a standby generator. These range from shoe-box size devices which will power a desktop computer for an hour or so, to much larger systems for a suite of servers in a computer centre.

If you just need to protect a few desktop computers, consider whether replacing these with notebook computers would be the simplest solution.

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Consider Demand Management

If you decide that equipment needs to be supplied by a standby power source, the capital cost of that equipment can be reduced by reducing the electrical load which it must supply. The investment required to achieve this “demand management” is often lower than the incremental cost the power system.

Demand management takes two forms:

  • Permanent reduction in power requirements, achieved by making some energy processes and equipment more efficient. This will have the added benefits of reducing ongoing electricity consumption, costs and environmental impacts.
  • Reducing the electrical demand by controlling some equipment. during periods of peak demand or during power blackouts. This can be sophisticated, using demand sensing and prediction, or simple using dedicated essential and non-essential circuits. Voltage-held relays can be used to automatically drop some non-essential loads (e.g.. room air-conditioners) when the power supply fails, so that that a generator will not have to supply these on start up.

If a computer system need protection, this would be a good time to have a close look at the computer equipment itself. We have seen computer centres which:

  • Could be completely decommissioned because of the growth in capability of the distributed personal computers. This was achieved, resulting in a 100% energy saving as well as obviating the need for a large back-up power system.
  • Could be updated, resulting in old, power hungry main-frames being replaced by much smaller, more powerful, mini-computers. This was also achieved, leading to very high maintenance, space, energy and air-conditioning savings, and reliability benefits.

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Consider Cogeneration

Cogeneration means the generation and use of electricity and heat. When a fuel is burnt in order to produce electricity, heat is produced. In most power stations, this is considered as “waste heat”. But many buildings that use electricity also use heat. If the electricity is generated in the building, the inevitable heat generation need not be wasted, but can be used for comfort heating, water heating, steam raising, product drying, and cooking, etc.

Using the heat which is normally wasted at a power station leads to lower costs (in most cases), and lower total greenhouse gas emissions. However, sometimes these savings are not sufficient to justify the necessary investment in the necessary equipment (engine, alternator, electrical controls) and other project costs.

Cogeneration requires an investment in an engine and electrical controls, etc. and sometimes this investment is not justified by the energy savings alone. But the incremental investment required for cogeneration (compared with a standby diesel without heat recovery) is more likely to be justified.

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Consider Standby Power and Generator Options

Again, the most obvious solution may not be the only, or indeed the best. Standby power and generator options include (but are not limited to):

  • A new diesel generator installed in your premises
  • Electrical connections and controls to facilitate using a transportable generator to provide power. This could be hired at short-notice, owned by others but kept on standby (for an annual fee), owned by you and also used for other purposes (e.g.. outdoor events). Generators are also available which can be powered by tractor PTOs; this could prove an economical option for organisations which have tractors.
  • A natural gas fired, reciprocating engine, cogeneration system
  • A steam turbine which is powered from an existing boiler on your premises. In small sizes (less than 1000 kW) these are inefficient but capital cost may be a more important consideration if the generator will only run for a few hours per year
  • A second hand diesel generator. Many diesel generators lose their value as their operating time approaches their life expectancy. This is a problem for an organisation which needs to run generators continuously (e.g. mining, oil rigs, remote settlements) but should be of very little concern to an organisation which is after an emergency generator which will never exhaust the remaining hours of generator life. Of course, some of the capital savings would have to be invested in a thorough survey of the diesel generator’s equipment.
  • Some electricity distribution companies offer “second-feeders” which are fed from a different part of the network. These will provide power in some circumstances which would otherwise lead a power outage. Carefully consider whether a second feeder will meet your requirements.
  • Some electricity distribution companies offer no-break and standby power supplies for an annual fee related to your maximum demand

For more information on power supplies, generator options, questions, comments, web site suggestions, etc, please contact us.

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