Harried Dutch commuters may not be entirely cognisant of the fact, but they may soon be travelling on one of the most environmentally friendly rail networks in the whole of Europe, if not the world.

Electricity generated by wind turbines already provides nearly half of traction power on the 2,900km ProRail 1.5kV DC network, out of total consumption of around 1.4 terawatt hours (TWh) per year.

That figure is set to rise to 100% by 2018 under a new green energy contract - thought to be among the largest yet signed in Europe - between power supplier Eneco and VIVENS, an energy procurement joint venture comprising Netherlands Railways (NS), Veolia, Arriva, Connexxion and rail freight firms.

According to Michel Kerkhof, account manager at Eneco, the deal has the potential to revolutionise how renewable energy is procured and utilised, both in the rail sector and other primary industries.

"What makes this contract and partnership unique is that a whole sector decreases its CO2 footprint enormously and sets an example for other sectors to follow," he states. "Mobility is responsible for 20% of CO2 emissions in the Netherlands, and if we want to keep travelling, it is important that we do this without burdening the environment with CO2 and particulate matter. This contract offers all Dutch citizens the option to make a climate neutral trip, regardless of distance."

Orange and green: powering the Dutch rail network with wind energy

Under the terms of the deal, half of the NS fleet of electric trains will run on green energy in 2015, rising to 70% the following year, 95% in 2017, with the goal of a 100% renewable network by 2018.

Eneco will supply 1.4TWh of electricity for the rail system - equivalent to the amount consumed by all households in Amsterdam - from wind farms that are in the process of coming on-stream. Half of them are situated in the Netherlands, and the remainder in Belgium and Scandinavia. After 2018, about half of the electricity demand will likely need to be provided by foreign sources.

Reconfigurable carriage: from passengers to freight and back again A reconfigurable railway carriage can carry passengers or freight when required.

"If the Dutch railways sourced 100% of the 1.4 tWh of energy they needed each year from within the Netherlands, this would decrease availability and increase prices of green power for other parties," explains Kerkhof. "That is why half of the demand will be sourced from a number of new wind farms in Belgium and Scandinavia, which have been specifically assigned for this contract.

"NS and Eneco have carefully selected a list of wind farms that fulfil their criteria of being traceable, sustainable - or renewable - and additional, or new. In the Netherlands, the green power is supplied from a wind farm in the Noordoostpolder and from Eneco's new Luchterduinen offshore facility.

"At the end of June, the first megawatt hours of power were delivered from Luchterduinen to the rail network. Starting in approximately 2018, that figure will rise to 100GWh annually."

A key objective is to avoid procuring energy from the limited existing number of sustainable energy projects in the Netherlands, thus promoting renewable growth both domestically and Europe-wide.

"This partnership ensures that new investments can be made in even newer wind farms, which will increase the share of renewable energy," confirms Kerkhof. "In this way, the Dutch railways aim to reduce the greatest negative environmental impact caused by CO2 in such a way that its demand actually contributes to the sustainable power generation in the Netherlands and Europe.

"This is also something we see in other industries. In the ICT sector Google and Eneco entered into a ten-year partnership to supply its datacentre with energy from a new wind farm in Eemshaven in the northern part of the Netherlands. In the chemicals sector, AkzoNobel uses sustainable energy from the GoldenRaand biomass plant to green its production processes. More and more companies want to make sure that the energy they use is sustainable, affordable, and available."

Healthy competition: project funding and the spectre of power outages

So far, so admirable, but can renewable energy hold its own in an increasingly competitive energy market or are projects such as the Eneco/VIVENS enterprise reliant on heavy government subsidies?

"No direct subsidies from the government are related to this contract - it is the result of a European tender procedure between market parties," states Kerkhof. "The wind farms all operate within the local subsidy systems - the Stimulation of Sustainable Energy Production (SDE+) in the Netherlands, the Electricity Certificates (El-Cert) in Scandinavia and Green Power Certificates (GSC) in Belgium.

"No direct subsidies from the government are related to this contract - it is the result of a European tender procedure between market parties."

"These subsidies bridge the gap between the cost of green energy and the grey energy market, and make it possible to build sustainable installations.

"Of course, wind energy costs a little more than non-sustainable energy, but the Dutch railways have managed to keep train ticket prices at par by continuously decreasing the use of energy per travelled kilometre and by closing this ten-year contract under attractive commercial conditions," he adds.

As the Netherland's premier rail operator, NS handles 1.2 million journeys a day and is something of a pioneer in the arena of climate-neutral travel. The firm has cut energy consumption per passenger per kilometre by roughly 30% since 2005 using new trains and more efficient driving techniques.

Dutch rail travelers also appear to support the concept of sustainable rail travel; in a recent survey, 80% of NS riders indicated that green energy was preferable to traditional forms of traction power.

But will that optimism wane if the wind fails to blow and rail passengers face service disruptions due to power outages? According to Kerkhof, Eneco's wind farm portfolio guarantees sufficient capacity to cover such eventualities.

"The main challenges associated with wind energy generation have to do with delays in realisation of a wind farm, but this can be mitigated by having a large enough pipeline of wind farms to source from," he explains. "Eneco ensures that there is always enough power available on the grid for the rail companies and we also guarantee that the annual amount of electricity needed for rail companies corresponds to the annual production of the wind farms."

Emissions statement: rail integral to Netherlands clean energy future

In June, a court in The Hague ordered the Dutch government to cut its emissions by at least 25% within five years in the first ever climate liability suit brought under human rights and tort law.

The landmark ruling comes after developers behind Holland's largest offshore wind installation, the 600MW Gemini project, signed €2.8bn worth of contracts to push the project towards its targeted completion date of 2017. The Netherlands currently has 2.7GW of wind power capacity in operation, most of which is onshore, and aims to reach 4.45GW by 2023, reports the BusinessGreen website.

Rail-air freight: can it work? Rail-air multi-modal freight systems have the potential to revolutionise the freight transport market.

In light of the historic events at The Hague, and the Netherlands' financial and cultural investment in renewable energy, what part does Kerkhof think the rail industry can play in the nation's green future?

"Rail companies are the basis for further sustainable energy, not only in the Netherlands but also elsewhere in Europe," he states.

"The greatest environmental impact is caused by CO2 emitted during power generation. Based on figures from 2014, prior to the partnership with Eneco, NS used 1.2TWh of electricity and emitted 550kt of CO2, while the complete VIVENS contract emitted 640kt of CO2. These emissions will be brought back to zero in 2018."