Syriza may be eco-friendly on renewables, energy efficiency and decentralised energy production but it faces internal tensions over plans for new coal plants and, potentially, the world biggest gas pipeline.

Syriza’s election victory has kindled hopes of an environmental champion pushing for greater climate ambition on the European stage, but the party will need to balance its green credentials with a commitment to new coal plants, and ambivalence about a major gas pipeline.

Syriza is in an alliance with a faction of the Greek Green party, which will have at least one MP in the new government, and it is seen by many as a tribune of European social movements, particularly environmental ones.

Elements of Syriza’s domestic agenda will delight environmentalists. The party believes in small-scale diversified renewables production, coordinated with local people through community-level decision making. It also plans a big expansion of energy efficient building renovations – seen as the most cost-effective means of simultaneously cutting emissions – and fuel poverty.

“Alexis Tsipras embodies the hope for a change of direction in the European council,” said the Green party’s co-presidents Rebecca Harms and Philippe Lambert, welcoming the election result. “The Greens/EFA group in the European parliament will do everything it can to support good cooperation between the EU institutions and the new government in Athens. Syriza’s failure would benefit only the extreme right.”

This last point is no doubt true. But Syriza is torn between an economy that has contracted at a scale and speed not seen since the 1930s and a sizeable chunk of its party that is eager for growth now, at any cost. The government will need to quickly reframe the debate about ‘sustainable growth’ or lower green expectations, or both.

Syriza also plans to build new coal lignite plants – albeit, as cleanly as possible. “To build one new lignite plant but replace two others which are of older technology and emit more pollution, could be seen in technical terms as an improvement,” Harris Konstantatos, a member of Syriza’s central committee, told the Guardian, from Athens.

But coal is also the most carbon-intensive of all fossil fuels, and environmentalists argue that ‘clean coal’ techniques simply displace pollutants from one waste stream, such as fly ash, to another, such as water outflow.

Syriza’s commitment to growth itself would be challenged by many European Greens, but Konstantatos said that ‘degrowth’ ideas would be viewed as “absurd” in the austerity-wracked Greece of today. Leading party thinkers see the ‘keep fossil fuels in the ground’ idea as equally inappropriate – when even Germany continues to burn coal.

“If we face fiscal difficulties from abroad in the medium term, then to burn more lignite instead of importing energy will seem a wise thing to do,” a Syriza source said. “If we don’t have money to import petrol then we will burn lignite which is free – not of a carbon footprint – but relatively cheaper. One way or another Greek lignite will be exploited.”

Syriza is also keeping cards close to its chest on the issue of an east Mediterranean gas pipeline to alleviate Europe’s energy security concerns, with gas from Cyprus and Israel.

The Guardian understands that informal – though not yet face-to-face – negotiations have taken place between Syriza and the EU over what could be the largest pipeline project in the world, and among its most politically fraught.

“It’s a big and complicated issue, requiring strategic choices in accordance with how relations between Greece and the EU develop,” a source said. “Unfortunately, the issues of energy corridors and energy security in general are seen through the lens of geopolitics, rather than ecology. It is safe to say that the national pipelines are part of larger renegotiation of Greece’s position in Europe’s architecture.”

An announcement may be made when the new government’s programme is outlined in parliament. The issue highlights the tightrope Syriza is walking between the radical intent of large parts of its membership and the compromises that may be foisted on it, if it is to deliver on its manifesto.

As its own positions make clear, “We are an eco-friendly party and protection of the environment is at the top of our agenda,” the Syriza MEP Kostas Chrysogonos told the Guardian. “We humans are part of mother nature and not its rightful owners. We should behave accordingly.”

The party was pledged to end a planned gold mine in Halkidiki, which would devastate the local environment, he added.

Syriza is suspicious of market-based mechanisms like the EU’s emissions trading system, which it sees as a way of distributing public subsidies to wealthy polluters, while doing little to tackle emissions. It publicly strives for a third way of economic development.

“We cannot and must not reproduce the well-known business-as-usual developmental models because we missed the rest of Europe’s industrial development train a century ago,” said Konstantatos. “It is rational for Greece to go green.”

“Smart micro-grids can make much more efficient use of renewables to cater for islands that are not connected with continental grid, or make changes at the regional level,” he added. “You don’t need to reproduce the carbon model, with centralised plant that distribute everywhere. We must not reproduce this.”

Here too though, Syriza will face some local opposition to wind turbines, fed by community resentment at wind farms centrally-licensed by the previous government with little regional planning, that enriched big industrialists.

Both reds and greens in Syriza share a belief in economies based on human needs and wellbeing, rather than consumerist wants. But it may take time for the fledgling government to resolve the tensions between these, and align them with a daunting reconstruction programme. It remains to be seen whether that time will be forthcoming.