Building a Smart Grid based on direct current

One small step for man, one giant leap for mankind

Neil Amstrong

In my first post about direct current I wrote about the war on currents. Today I will highlight a Dutch pilot project to build a smart grid based on direct current. The DC-network will be realized in a new greenhouse near Schiphol Airport in the municipality of Haarlemmermeer. It was granted a subsidy by the Ministry of Economic Affairs, Agriculture and Innovation in December 2011, and will be operational in 2014. The DC-net will be self-sufficient and has a backup to the underlying alternating current distribution system (hereinafter AC distribution). The electrical output of the DC-net is between 300 and 1500 watts.

The DC-network consists of a ring around the sustainable horticulture area PrimAviera near Schiphol (Haarlemmermeer). The energy will be generated by both solar panels and combined heat and power plants (hereinafter CHP), which will be connected to the DC network. The energy generated will be used for lighting and ventilation of the greenhouses, which will be connected to the ring. Also charging points for electric vehicles will be connected to the DC network.

What makes this project unique?
Networks are needed to transport electricity from the place where electricity is generated to the place where it is used.  A major task for operators of electricity networks based on alternating current is to ensure stability of the AC-grid. Imbalance in supply and demand of energy disturbs the stability of the AC-grid and can lead to a widespread blackout. Maintaining stability is relatively easy with centralized energy production, but becomes more difficult with decentralized energy generation. With The Netherlands slowly following the lead of other countries towards more sustainable energy and decentralized generation of electricity ensuring stability of the AC-grid becomes more difficult.

In a DC network ordination between supply and demand of electricity also exists. However, this balance question does not have to be accurate with millisecond as in the AC-world and can be planned well. Because storage of local DC is also possible (batteries typically use direct current), maintaining the energy balance is more easy, particularly as the management is done by electronics.

Thanks to the technical characteristics of DC, the DC network manager can determine that the locally generated energy is used before energy generated elsewhere is transported to the user. If there is an excess in energy generated locally it may be stored locally, or the excess can be transported to other local consumers. If there is more energy generated than needed in the DC grid the excess can be supplied back to the AC grid.
In essence, the DC network doesn’t need a AC-network as an underlying network. So in case of a blackout the DC smart grid in Haarlemmermeer will prove to be a beacon of light.

The phenomenon of DC will lead to different forms of energy planning and open up new markets. Now let’s talk about innovation! That’s one small step for man, one giant leap for mankind.

This contribution was originally written for and published by TEDxBinnenhof  in close collaboration with Bob Zijderveld, independent Consultant DC, Conventions and member of the board at Stichting Gelijkspanning. Any mistakes or technical errors and omissions are solely the responsibility of the author. For more technical background please contact Stichting Gelijkspanning or Direct Current.

The war of currents will become a battle lost

“I have never failed”

Thomas Edison

The headlines from the Dutch Newspaper NRC Handelsblad on Thursday, April 26th 2012 read:

Global player landing in Rotterdam

We would have chosen a different headline, because the global player meant is General Electric, founded by Thomas Edison. He improved the light bulb and lay the foundation for today’s electrical distribution system. His company, GE, is an important linking pin between generating and using renewable energy. That linking pin is direct current (DC). A technology that lay at the foundation of General Electric over 150 years ago and a technology that will be used in a smart grid pilot at the municipality of Haarlemmermeer that will start soon.

War of Currents
In 1879 Thomas Edison introduced his improved version of the light bulb. He soon discovered that an electrical distribution system was needed to provide power to light bulbs. Therefore he built the world’s first electricity network with a voltage of 110 Volt. It was based on direct current (DC), which worked well with incandescent lamps, which were the principal load of the day, and with motors. Direct current systems could be directly used with storage batteries, providing valuable load-leveling and backup power during interruptions of generator operation. Direct-current generators could be easily paralleled, allowing economical operation by using smaller machines during periods of light load and improving reliability. The disadvantage of direct current at that time was that power generation needed to be close to the load, because there was no efficient low-cost technology that would allow reduction of a high transmission voltage to a low utilization voltage. To overcome this disadvantage Edison choose a distributed generation system.

The alternating current system (AC) had first developed in Europe. In North America one of the believers in the new technology was George Westinghouse, one of the opponents of Edison. Westinghouse was willing to invest in the technology and hired, amongst others, Nikola Tesla to study the design of Edison and further develop the alternating current system. After vigorous campaigns by both Edison and Tesla to demonstrate the danger of using the opponents system alternating current became the dominant standard, both in Europe and the USA.

The use of alternating current gave the opportunity to increase the distance between power stations and loads. Alternating current set the stage for large scale, centralized power generation.

The silent revolution towards DC
The alternating current network dates from a time that load consisted of lamps, heaters and electric motors, but the development of technology hasn’t come to a standstill since setting the standard to AC. Direct current has been returning nearby in three different forms: electronic devices, sustainable energy and energy storage.

The invention of the “transistor” in the year 1947 forms the starting point of the silent revolution towards direct current. Transistors form the fundamental building block for the development of complex electronic equipment. Currently almost all current electronic equipment and electrical devices use DC internally. Alternating current from the grid is converted to direct current using a AC/DC transformer for internal use in electronic equipment like mobile phones, computers and led-lights.

The last decades see a shift towards sustainable energy within the European Union. The share of power generated by wind, water, solar and co-generation is rising, especially in Germany with it’s feed-in system. All those forms of sustainable energy generate direct current which has to be transformed to alternating current to feed it back in to the grid. To be able to integrate offshore wind farms the Dutch grid operator Tennet, which owns part of the German grid, wants to construct a DC network. High Voltage Direct Current is already used for bulk transmission of energy from distant generating stations or for interconnection of separate alternating-current systems.

Sustainable power generation will be rising in the Netherlands too. For example solar power is expected to grow rapidly in The Netherlands, as grid parity for consumers and small business is (almost) reached at current retail electricity prices. Some municipalities and local energy cooperatives are already pioneering with large scale solar energy systems, where people without a suitable rooftop crowd-fund the needed investment. In return they receive the electricity generated instead of a financial return.

After sustainable energy has been transformed to alternating current for transport over the grid it has to be converted back to direct current again to be used by our electronic devices and led-bulbs or to be stored in (car) batteries. That doesn’t sound very efficient does it?

This does bring us to the third form of DC we encounter close by: batteries. With the coming age of the electric car and all the fuzz about ‘range anxiety’ it might be good to know a Dutch company exists that can deliver a range of up ot 300 kilometers using a DC powertrain and replacing the AC/DC transformer with extra batteries.

Rotterdam or GE can be the connection

In the municipality of Haarlemmermeer Direct Current BVStichting Gelijkspanning (the direct current foundation) and their partners are working on a smart grid based on direct current. The pilot has received subsidy from the Ministry of Economic Affairs, Agriculture & Innovation. This regional grid will be operating on voltages in excess of 300 Volt. The smart grid based on direct current will link sustainable power generation with users of the electricity, for example charge stations for electric cars.

Direct current could also be used to provide shore supply of electricity to ships in the Rotterdam harbour significantly improving air quality in the Rotterdam area. If Haarlemmermeer deems to far for Rotterdam perhaps a GE executive is landing at Schiphol Airport to visit the Rotterdam plant can drop by and learn more about what Stichting Gelijkspanning, Direct Current and their partners are up to with DC, the technology used by it’s founding father Thomas Edison. That would return GE to its roots and help bridge the gap between sustainable power generation, power storage and the sustainable use of electricity. It could also make the war on currents lost by GE a lost battle.

As they say in Rotterdam:

Not words but deeds!

This contribution was originally written for and published at TEDxBinnenhof in close collaboration with Bob Zijderveld, independent Consultant DC, Conventions and member of the board at Stichting Gelijkspanning.

Uit de inbox: Dialoogbijeenkomst Groen is POEN! Anders denken loont! – 25 januari

“Groen is poen! Anders denken loont!” Dat is het thema van de dialoogbijeenkomst georganiseerd door Vernieuwing Bouw, TNO, de Vrije Universiteit Amsterdam in samenwerking met Energiesprong en Building Brains. De bijeenkomst vindt plaats  op woensdag 25 januari 2012, van 14.00-18.00 uur. Wij nodigen u van harte uit om hierbij te zijn.

In opdracht van het Ministerie van Economische Zaken Landbouw en Innovatie heeft TNO in samenwerking met de Vrije Universiteit van Amsterdam 12 succesvolle projecten belicht die duurzame samenwerking en innovatie als thema hebben. Vragen die centraal staan:

  • Wat maakt deze projecten succesvol?
  • Samenwerking en innovatie in de bouwsector verloopt moeizaam maar waarom lukt het juist in deze projecten wel?
  • Wat kunnen wij van ze leren?
  • Wat kunnen we samen doen om deze successen op te schalen?

Naast een inhoudelijke dialoog over de projecten en de achterliggende ‘oorzaken van succes’ zullen er plenaire sessies zijn waarin vooraanstaande sprekers Elco Brinkman en Thomas Rau wordt gevraagd om hun reactie.

Een van de onderzochte projecten is het energieservice bedrijf (ESCo) Rotterdamse Zwembaden van Strukton. Een aantal collega’s van Strukton is aanwezig om meer uitleg te geven over de gehanteerde werkwijze en natuurlijk ook om inspiratie op te doen vanuit de andere 11 succesvolle projecten. Ik kan er zelf helaas niet bij zijn.

Meer informatie

Mocht je je alvast in willen lezen dan kan dat op de website van Strukton of in de factsheet (pdf). Of vul ondestaand contactformulier in dan nemen mijn collega’s Michel Heijnekamp en Jeroen Mieris contact met je op.

[contact-form-7 id=”5170″ title=”Strukton ESCo”]

Disclaimer: als consultant maatschappelijk verantwoord ondernemen hou ik mij binnen Strukton onder andere bezig met het promoten van duurzame oplossingen van Strukton.