At a suburban Kyiv railway station, two carriages painted in the blue and white livery of Ukrainian Railways sit on the main platform, their diesel engines running as snow steadily falls. The train is not going anywhere but it is providing a vital service for dozens of people who have been left without power and basics like running water or heating. These are Ukraine's Invincibility Trains, designed to boost public morale and provide some comfort as a bitter winter coincides with intensifying Russian attacks. In one of the carriages, Alina sits watching her infant son Taras playing with toys provided by international charities who help run the service. It's winter and it's rather cold outside, says Alina which is something of an understatement. With the effect of the wind-chill, temperatures this week in Kyiv have hit -19C. It is bitterly cold.

I live in a new building on the 17th floor, but we have no elevator, no electricity and no water supply, says Alina. As Taras plays with his toys, she says it is also a relatively safe and comfortable place for her daughter to meet friends. It is also a welcome distraction for Alina, whose husband works all day in a factory, but she suddenly starts to stutter and weep as she tells me about her 54-year-old father who was killed at the front two years ago in a summer offensive near Bakhmut. As she regathers her composure, Alina says she will definitely come back here and welcomes the relief the train brings from the weather and the nightly Russian strikes.

Ukraine's President Volodymyr Zelensky has accused Russia of deliberately exploiting the bitter winter to target power stations, energy storage facilities and other critical infrastructure. Kyiv's Mayor, Vitali Klitschko, somewhat controversially this week also suggested that city residents, who could, should leave Kyiv to help ease pressure on critical resources. It was a comment seized upon by Russia as a sign of resignation and defeatism. But despite such obvious hardships, most people here in Kyiv remain stoic and are prepared to put up with them.

For Yulia Mykhailiuk, Ihor Honcharuk and their one-year-old son Markiian, that means heating building bricks on a gas stove to try to warm up the rest of their small apartment. The flat, in an old Soviet-era apartment block on the east side of the Dnipro river, is a temporary move because their own home was partially damaged in a Russian attack last August. We've had electricity today for something like four minutes, Ihor tells me. All of our charging stations and power banks have no energy left in them.

The large batteries the couple have bought, like many city residents, to charge up when electricity does return are of no use when it comes to heating appliances because they run down so quickly. For now, dressing the baby up in multiple layers of clothing is the only solution, but Yulia says at the weekend they will heed Mayor Klitschko's call and temporarily move away from Kyiv to her parents' home outside the city, although she says it's a decision they have made for themselves and not because of pressure from the mayor's office. The energy crisis is not the only reason to move. Just across the courtyard from their new, temporary home, a recent Russian drone strike hit an apartment block, badly damaging several homes.

Kyiv's problems are exacerbated by the fact it has borne so many Russian airstrikes against homes and critical infrastructure installations and, as home to more than three million people, the power shortages impact many people. The most recent Russian attacks against energy installations in the capital and other big cities have had a cumulative effect that is much worse than before. Klitschko said strikes on Monday night had caused the worst electrical outage the city had yet seen, and on Tuesday more than 500 residential buildings were still without power. Around the clock and across the city, engineers from private energy companies and the municipal authority are repairing power plants hit directly in Russian strikes or installations indirectly affected by them.

Stanislav or Stas has also come down to the Invincibility Train to get warm, meet friends and get some power for his phone. The eleven-year-old says his home is very cold and there'd recently been no power in the family's apartment for 36 hours. When I hear something flying it's really scary, because you don't know if it will explode now, or if it will fly on and you survive. As we perch on the top bunk of the carriage where he is sitting with another friend, Stas is frank about the impact of the war on his generation.

Everyone in Kyiv is putting a brave face on things. This extraordinarily cold winter, even by Ukrainian standards, will not last for much more than a couple of months and the energy crisis will ease. What most people fear is that, despite some optimism at the end of last year, there is no end in sight to the war itself and the inevitable loss of life.