Editor's Choice


Nick Denbow's European report: DC power distribution is efficient but the Internet is greedy

September 2018 Editor's Choice News

Changes in the technology around us that we work with and even create when involved with automation and control, are having a wider effect on society as a whole. Two areas that have been influenced this way are the growth of alternative methods of power generation and transmission, and the enormous power demands of the Internet, which will lead to a crisis somewhere.

Last November, this column described the long distance HVDC power transmission systems being installed by ABB, taking power across China, and also those used on undersea links between the mainland and offshore islands, or even oil industry offshore platforms. In reverse, similar DC power links deliver the power from offshore windfarms to national networks. Now GE has described how their MVDC technology from the GE Power Conversion business has been applied by Scottish Power to deliver extra power across existing lines between North Wales and the island of Anglesey (it is a quirk of the UK power industry structure that Scottish Power also supplies England and Wales).

The GE project converted the existing 33 kV AC transmission links to work with 27 kV MVDC, using GE power electronic inverters in sub-stations at either end of the line. This will increase the power available over the existing cables by 23%, to meet the future needs on Anglesey, without any additional environmental impact. GE point out that these same techniques are being applied in wind and solar farms, facilitating direct connection to an efficient MVDC power collection grid, giving a lower cable cost and less expensive installations.

Needless to say, the installations in Wales and Anglesey will be monitored by remote asset management systems, operated by GE engineers via the Internet.

DC power networks

DC power is becoming more prominent, both at the beginning and at the end of the grid. It is produced by wind turbines and solar PVs and used by everything from smartphones, laptops and electric cars, to the data centres that keep the Internet running.

However, having to convert back and forth between AC and DC along the way leads to wasted energy through resistance and heat – is this just to enable an interface with our old fashioned infrastructure? Our office buildings have computer network access on every desk, and even at home, the power sockets are fitted with added USB power outputs. The modern LED lighting systems, and ordinary domestic lamp bulbs, now use low power DC supplies. Why then do we need AC for more than power duties such as heating and cooking? Maybe it is time to convert homes to have most outlets just providing a DC supply from one power source housed in the local sub-station.

Internet burnout

There is a problem in adding too much emphasis on interrogating, monitoring and controlling everything via the Internet. The problem is the amount of power needed to run the data centres that store and distribute our data. In 2015, data centres worldwide consumed 30% more electricity than the whole of the UK demand for power – they took 3% of the global electricity supply. Ian Bitterlin, Britain’s foremost data centre expert and a visiting professor at the University of Leeds, says the amount of energy used by data centres is doubling every four years: and he points to a study focused on Japan, which suggests that their own data centres will consume the entire Japanese electricity supply by 2030. Carry on at this rate, and at worst the whole Internet will fail – at the very least there will need to be access charges and taxes to control the growth in Internet use.

Most data centres are sited in cold climates, to assist with cooling the electronics, as most of the power they use seems to be consumed by large cooling fans. While the heat generated directly contributes to global warming, the power used in 2015 accounted for 2% of total global greenhouse gas emissions, giving the data centres the same carbon footprint as the whole airline industry.

I had hoped that there would be an answer to this problem by using solar or other green DC sources to power these centres, but this seems unlikely, if the major power requirement is for the fans. Naturally, research continues on reducing the data centre demand for power, but it may be too late!

Nick Denbow spent 30 years as a UK-based process instrumentation marketing manager, and then changed sides – becoming a freelance editor and starting Processingtalk.com. Avoiding retirement, he published the INSIDER automation newsletter for five years, and then acted as their European correspondent. He is now a freelance Automation and Control reporter and newsletter publisher, with a blog on www.nickdenbow.com





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