Archive for the ‘Electricity’ Category

Data centers and the environment: The case of Facebook

September 24, 2015 1 comment
Facebook data center engineer

A Facebook data center engineer

There has been an increased uptake and use of the Internet especially  social media by many in the world. This has led to rapid deployment of infrastructure to support this increased demand.

This infrastructure consumes power. It is estimated that data centers that power the internet world-over consume about 1.3% of the world’s total electric power. This might seem small but if you consider that Facebook consumed about 532 million kWh in 2011 (must be close to double that amount now). At current Kenyan electricity tariffs, that’s about 10.6 Billion shillings in power bills. Google consumed just over 2 billion kWh during the same time to power their servers world-wide. With most of this power being from coal plants, data centers are attracting the attention of groups such as green peace who are have launched campaigns such as ‘unfriend coal’ which was geared towards forcing Facebook to lower its dependence on coal to power its service.

With pressure piling on data centers to lower their carbon foot prints, innovation and new way of thinking is needed. One of the low hanging fruits is to build new data centers in regions that use green energy. One of the prime locations now for setting up data centers is Iceland. The country generates all of its power from geothermal steam and hydro. The cool weather there also means that natural cold air that is about 5.5 degrees C on average is simply circulated in the data center to cool the equipment as opposed to using air conditioning systems for forced cooling. This means that a server operating out of Iceland is cheaper to run and has a near zero carbon emission attached to it. According to Verne Global’s findings in 2013, the 10 year energy cost (the length of a standard data center hosting contract) for 1 megawatt of IT load in Keflavik, Iceland is near $3.5 million, compared to nearly $23 million in London, $20 million in Frankfurt, $12.5 million in Chicago, around $6 million in Oslo, Norway. The other bonus is the geographical location of Iceland makes latency from a server there to Europe and US nearly equal at 40ms.

However, with the likes of Facebook who have already invested a lot of money on data centers in the US, they cannot simply cart it to Iceland. They have therefore come up with innovative ways to lower their data center energy costs. It is estimated that about 25% of power in a data center goes to cooling, 10% is wasted in the conversion from AC to DC and back to AC voltage, IT load taking 46% of the power (25% servers, 8% network and 13% storage) there is a huge opportunity to lower the IT load portion and cooling portion.

IT load efficiency

Facebook did some research and found out that servers running low-level loads use power more inefficiently than idle servers or servers running at moderate or greater loads. In short a server should either be kept idle or at moderate/high load, not in low load. The traditional method of load distribution on a group of servers is known as round robin. This method is efficient on computing resources but inefficient on power use. Facebook developed a new way of doing things known as Autoscale.

Autoscale is designed to distribute incoming requests to the servers so that they are either idling, or running at medium/high-capacity and not in between. It tries to avoid assigning workloads in a way that results in servers running at low capacity. This was informed by a test that was done by Facebook engineers. In this test they found out that a server that is in idle mode consumes about 60 watts of power. If some light lower level load is applied to the server, the power consumption goes from 60 to 130 watts. However, if the same server is run at medium or higher loads, the power consumption is about 150 Watts; a 2o watt difference between low load and high load. This means that its more energy-efficient to give an already moderately busy server some more load (20 watts extra consumed) as opposed to giving this load to an idle server (70 watts extra consumed if you do this). Autoscale will also reduce the number of servers sharing the load so that it puts as many servers as possible in idle mode. In low traffic periods such as American midnight. Autoscale dynamically adjusts the size of the server pool in use, so that each active server will get at least a medium-level CPU load. Servers not in the active pool don’t receive traffic.

The other method deployed to reduce power consumption is the reduction of power transformation. There is about 10-15% loss in transformers and rectifiers found in UPS’s. In most data center setups, mains AC power is fed to a centralized UPS. The UPS converts this AC to DC and back to AC to supply the servers with power. This AC-DC-AC conversion results in about 6-12% loss. a way to lower this loss is to have the servers supplied directly by mains AC power but have localized UPS’s on each rack that can give up to 45 seconds of backup power as the diesel generator turns on in case of a power outage (a very rare occurrence in the developed world). Eliminating centralized UPS’s means that data centers can save about 10% of power. Feeding direct AC power from the grid to servers can be a tricky affair, this is because reactive components in the grid such as motors that power everything from escalators to coffee grinders lower the power factor and increase reactive power. The deployment of reactive synchronous condensers in data centers lowers reactive power which is responsible for some losses depending on power factor of received power. Facebook has deployed in-house custom-made reactor power panels which try to bring the power factor as close as possible to unity. Other than improving the quality of power, the Facebook reactors also reduced harmonic distortion in the power system which causes delays in generators kicking in when there is a detected power loss from the mains.

Use of 277Volts instead of 120 or 240Volts

Facebook hardware is also designed to operate at 277 Volts AC as opposed to the standard 120Volts in the USA main supply systems. The reason behind this is simple. with US 3 phase power being supplied at 480 Volts, the single phase neutral doesn’t come out at the 120Volts but at 227 Volts (you can use imaginary/complex number cube root of 1 components to derive this). The lowering of 227Volts to 120Volts by a transformer leads to about 3% transformation losses. So operating the servers at 277Volts and not 120Volts saves 3% power. The diagram below shows how a servers efficiency improved with the use of a higher voltage.

Hewlett-Packard server power supply efficiency as a function of load

Hewlett-Packard server power supply efficiency as a function of load (c) Syska Hennessy Group

A server operating at 240Volts (which is what we use in Kenya) is 91% efficient at 50% load compared to a similar server operating at 120Volts. jacking up this to 277Volts improves efficiency to 92% compared to a server at 120Volts at 89% efficiency on 50% load. The reason why America uses 120Volts is because in the early days of electricity, bulbs were made of carbon filaments that lasted longer if operated at 120Volts than at 230Volts, because most of electricity was used for lighting, it made sense then to run the grid at 120Volts. Later, when electricity went to Europe and Asia, technology had improved and the tungsten filaments could do higher, more efficient voltage at 240Volts.

Simpler cooling and Humidity control

About 12% of the cooling energy consumption goes to delivering the cold air at the point of heat rejection. By use of a ductless cooling system, the cold air is delivered at the center of the data center and with additional smaller cooling systems at the rack where the heat is generated, substantial power savings can be achieved.

The use of a vapor seal can also play a critical role in controlling relative humidity, reducing unnecessary humidification and dehumidification. If humidity is too high in the data center,conductive anodic failures (CAF), hygroscopic dust failures (HDF), tape media errors and excessive wear and corrosion can occur. These risks increase exponentially as relative humidity increases above 55 percent. If humidity is too low, the magnitude and propensity for electrostatic discharge (ESD) increases, which can damage equipment or adversely affect operation. Also, tape products and media may have excessive errors when exposed to low relative humidity.

Most equipment manufactured today is designed to draw in air through the front and exhaust it out the rear. This allows equipment racks to be arranged to create hot aisles and cold aisles. This approach positions racks so that rows of racks face each other, with the front of each opposing row of racks drawing cold air from the same aisle (the “cold” aisle). What this does is that it makes it easier to draw out hot air from the hot isles before it mixes with the cold air which lowers the cooling efficiency.

compressor_efficiencyThe other method of lowering cooling costs is through the use of multi step compressors for the cooling systems. Most traditional cooling systems simply switch on the compressors at full load when the thermostat input dictates that cooling should happen. a 4 step compressor operation showed that compressors operate at different efficiency at various steps. The diagram  on the side shows that the compressor in question is most efficient at step 2. The cooling system is designed in such a way that the compressor operates at step 2 most of the time.  Off the shelf cooling systems work well but are grossly power inefficient for use in data centers.

The internet is currently moving towards cloud computing. This essentially means that data centers will continue to grow and soon the power consumed by data centers will pile pressure on the grids and the environment. The use of green energy sources and innovation will go a long way in reducing the contribution of the Internet to global warming.

How Kenya can enjoy lower electricity tariffs

March 1, 2013 3 comments

???????????????????????This week, Kenya Power company announced a plan to increase the electricity tariffs and connection fees by about 45% from the current prices. They have also proposed a reduction in off-peak tariffs by about 20% to encourage heavy power users to utilize off-peak periods for their consumption. Off-peak in Kenya is from 11PM to 5AM where power consumption is about half the peak consumption.

The move to lower the off-peak power tariff is something I have been advocating for because doing so will lead to the following:

  1. If heavy users shift their consumption of power from peak time to off-peak time, then the spike in demand will reduce. Power for peak load conditions is mostly generated from sources that can come into and out of the grid at short notice, these are mostly fossil fueled plants. Lowering the % of power generated from fossil fuels can considerably lower the overall electricity costs. Take a look at the fuel adjustment figure on your electricity bill to understand what impact lowering this figure can have on your overall bill. If electric power utilization in Kenya were nearly a straight line, there would be no need for introduction of expensive peak load power plants into the grid as base and intermediate load plants can serve customers at a lower cost.
  2. The utilization of off-peak period by heavy users such as factories can lower their cost of production because energy is a huge component of manufacturing costs in Kenya. Kenyan manufacturers pay 21 US cents per KWh compared to Egypt and South Africa which pay 3.1 and 4 cents per KWh of electricity respectively. Power costs are the main reason behind many manufactures shifting base to outside Kenya.

History of Electric power Monopoly in Kenya

In 1908, Harrali Esmailjee Jeevanjee (Jevanjee Garden in Nairobi is named after him), a wealthy merchant in Mombasa bought a second-hand generator from Seyyied Bargash who was the sultan of Zanzibar. The Sultan had purchased this generator from spice money in 1875 to light up his palace and nearby streets in Zanzibar.
At around the same time  an engineer, Mr Clement Hertzel, was granted the exclusive right to supply electricity to the then district and town of Nairobi. This leads to the formation of the Nairobi Power and Lighting Syndicate. in 1922 the Mombasa and Nairobi generators are merged under a new company incorporated as the East African Power and Lighting Company (EAP&L). Between 1922 and 1983, EAP&L expands into East Africa and builds power networks and sales the distribution rights to the respective governments. By 1982, EAP&L was only present in Kenya and it changed names to Kenya Power and Lighting company (KP&LC).

Breaking the Monopoly

Since 1908, electricity distribution model has been an expansion of the original one consisting of a centralized source of power shared by many. The acquisition of exclusive rights from day one by Clement meant that no one had the permission to generate and distribute electricity. A Monopoly was therefore born. Kenya can considerably lower its power distribution and generation costs by opening the market to several players. I have discussed in detail in a previous blog post how this can be done here

Improve generation and distribution efficiency to lower costs

A huge chunk of the electricity costs go towards three things.

  1. Paying for the capital expenditure in the generation and distribution network equipment: Most of the CapEx comes in form of loans from ‘development’ banks and western foreign governments. We can considerably lower the cost of these loans by borrowing in the currency in which we will buy the equipment in or better borrow from the Chinese who are giving the lowest long-term development loan interests.
  2. Costs introduced by inefficient systems: The Kenyan power grid is inefficient. We lose about 7% of the generated power due to poor electric lines and about 10% due to use of old inefficient generating systems and transformers. My former Electric transmission lecturer who was also the then director at KIRDI reckons that improving the electricity grid efficiency in Kenya by 1% can save the economy about 7 Billion shillings annually.
  3. Idle capacity costs introduced by a short peak time demand period: During off-peak, the idle capacity becomes a cost, See how idle capacity can become a cost hereBy spreading the load over a 24 hour period through encouraging heavy users to use off-peak power, the component of idle capacity costs in the operating costs of the national power system can be drastically reduced leading to lower electricity bills to consumers.

If the above costs are reduced as outlined, the Kenyan consumer can continue to enjoy lower power tariffs for a long time to come. The reason why other countries can afford to offer power at five times below what Kenya is offering is because they adopted these measures to lower the cost of electricity.

Kenya Power Needs To Be Penalized For Blackouts

April 25, 2012 9 comments

The rainy season in Kenya is synonymous with prolonged and frequent power outages. As I write this, I am seeing very many tweets from people complaining of going three days in a row without power in their homes. Kenya Power seems overwhelmed in ensuring reliable supply of power to many of its customers. There have been calls to end the Kenya power monopoly by licensing other independent power utility companies to compete with Kenya Power. I have even discussed how this monopoly can end in a previous blog post here.

One thing worth noting however, the Kenyan situation is fairly better compared to the situation in Nigeria or Angola. For example, in Lagos, power is available only about 35% of the time and people have to depend on private generator sets to cover for the deficiency. in Nigeria fuel is 1/3 times cheaper than here in Kenya and the use of personal gen-sets in Kenya is therefore an expensive affair.

I have also discussed on a previous post on how the introduction of a Demand Response Provider can help lower the level of investment in power generation systems in the country by eliminating or leveling off the peak power demand curve. I would like to revisit the issue of the use of demand response providers but from a slightly different angle.


As opposed to Megawatts which is a measure of quantity of power consumed, Negawatts measures the quantity of power NOT consumed (in essence negative watts). Assume your house consumes about 10 Kwh power day like mine. If for some reason there is no power supply to my house for a day then my Negawatt consumption is equal to the power I have not consumed = 10. At the current tariff, a Kwh is about 18 shillings bringing my total daily power consumption to 180 shillings.

So if we price Negawatts at a rate of 25 shillings, then if there is a blackout in my house for a day then the cost of Negawatts “consumed” is 250 shillings. This will be the amount the utility provider owes me for not consuming power (either though my own deliberate action or by a provider caused blackout).

This therefore means me not consuming power costs Kenya Power more than if I consume power. What will happen is that this Negawatt tariff will essentially be a penalty of sorts to the Kenya power management and staff for not providing me with power, the Negawatt cost will come from their profits and bonuses. There is no reason why Kenya power should declare a 6.2Billion Shilling profit in the wake of very unhappy customers, some of these profits should be used to pay off aggrieved customers who have lost business and comfort due to their inefficiency.
This therefore means Kenya power will get penalized by their consumers by the hour for blackouts caused at a rate higher than if they would have supplied electricity to these consumers.

At the rate of 18 shillings per Kwh, my monthly bill of power consumption will be approximately 180 x 30 = 5400 shillings, assuming i experience blackout totaling to 10 days, then my power bill becomes without Negawatts penalty is  (180 x 20) =3600. However, with Negawatts penalty it becomes (180 x 20) -(250 x 10) = 1100 Shillings. So Kenya Power gets penalized 2500 shillings for the loss suffered by my business or home due to lack of power which i am now so dependent on.

This set-up will spur Kenya power to improve on their response times, invest in more robust distribution networks and increase staff output as they all work towards now losing money due to inefficiency.

At the end of the day, the customer will enjoy better power supply and Kenya power will not lose money due to Negawatt payouts to consumers.

There is need to end the Kenya Power monopoly

January 17, 2012 6 comments

As I write this, the social media is abuzz with Kenya Power customers venting their frustration at the electricity distributor over a message they sent to all their customers on prepaid meters. This message was on their intention to deduct 30 Kwh from their existing units loaded on their meters so as to recover a similar number of units that came pre-loaded in the meters during installation. The truth of the matter is no matter how vitriol their “tweets” towards Kenya power will be, It will go ahead and deduct the units from users’ meters and the users will still remain their customers.

After the break-up of the East African Community, the existing power company (East African Power and Lighting Company) broke up into three companies for Kenya, Uganda and Tanzania with the Kenyan one taking the name Kenya Power and Lighting Company (KPLC), KPLC was a vertically integrated entity responsible for the generation, transmission and distribution of electric power in the country. The Kenya electric power act of 1997 led to the breaking up of this vertical integration and three entities were formed, Kenya electricity generating company (Kengen) and Kenya Power and lighting company. The role of power generation was now moved to Kengen. The third unit was the Electricity Regulation Board which was a semi-autonomous regulator. This act also allowed the introduction of independent power producers (IPPs) who could now generate power and sale to KPLC at competitive rates to the government-owned Kengen. Subsequent acts of parliament such as the energy act of 2006 led to the refinement of the 1997 act and addition of the energy regulatory commission and the establishment of KETRACO (Kenya Electricity transmission company) which took over the role of electricity transmission from KPLC was further established. This left KPLC with only one role: that of distribution of electricity.

What all these acts have failed to do, is to open up the customer facing end of the whole electric power value chain to competition. KPLC which recently re-branded to Kenya power, still maintains the monopoly of electricity distribution in the country. The result is poor service delivery to option-less customers who have now resorted to social media to air their frustrations.

Kenya Power has been struggling with the billing and collection of post paid electricity consumption, the process was very labor intensive and led to negative cash flows. The adoption of prepaid meters transferred the meter reading and top up to the end-user hence saving on labor costs and at the same time instantly converted their cash flow into positive cash flow as users now pay before consumption. It’s the dream of any business to wield the powers to instantly convert cash flows that way.

With all this, I am of the opinion that the 2006 energy act needs to be repealed to allow competition on the electricity distribution front.
How will it happen? will Kenya Power competitors have to build parallel networks to supply electricity to end users?
The answer is No. what the government needs to do if change the law and make Kenya power an infrastructure provider and let it run the existing electricity network in a 50:50 partnership with private companies. It will then lease this network to several private/independent power utility companies that will buy electricity from Kengen and IPPs and pump it onto the network that they have leased from Kenya Power. end users can now chose which supplier they want to use (based on price, service delivery etc) and the install a meter from that company. They will now be topping up the meter with tokens bought from the meter supplier and hence effectively using their electricity. Users can therefore have several meters from different suppliers and switch across them depending on prevailing prices and tariff offers (Just like what is currently happening in the mobile sector). Because of the 50:50 partnership with a private player, Kenya power can upgrade this network and make it more resilient and less prone to failure/down times. While at it, they can also make it a smart grid.

How will the different “electricities” (for lack of a better word)  from the different power companies that run on the Kenya power cable be identified? This is easy to do, let each company add a low harmonic modulating carrier to the 50Hz supplied by Kengen and IPPs and then transmit it. This carrier tone can only be decoded by the correct meter and returned to the original 50Hz for use. In more familiar terms, it will work just the same way a Safaricom SIM card can only associate with the Safaricom network and not Orange or YU.

This approach will go a long way in introducing competition to the distribution end of the power supply chain, this competition will lead to improved service delivery to the consumers.

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