Warmth from the earth and air: could heat pumps replace our gas boilers? | Hacker News Reader

Warmth from the earth and air: could heat pumps replace our gas boilers?

theguardian.com

19 pointsGordonS13 comments

... as long as thewre aren't that many of them and the electric energy infrastructure can bear them, of course.

Here (Italy) the "base" contract for electricity is 3 Kw, if you install a heat pump you need a 4.5 Kw one, very often a 6 kW one.

The good news may be that heat pumps used for heating homes largely have peak hours in the late afternoon/evening/night and this can help leveling the production (traditionally office/industries/workshop need energy during the day and at evening/night there is over-production).

Still when you start adding up KW's, the size of cables, transformers/transforming stations comes into play.

Imagine a street block in a city, not too large, let's say 10 buildings with 24 flats each, they now need 240x3=720 KW, the current transforming station serving the block is likely around 400-450 KW, i.e. 20% more than half the theoretical needed power (how this is calculated is complex, it involves an estimated simultaneity factor and a utilization factor, this is only a rough approximation).

Now, suddenly you need double that amount, 6x240=1440 KW, even if you lower the mentioned factor, it is unlikely that you can get away with anything smaller than 650-750 KW.

And of course the cables need to be upgraded as well.

And recharging electric cars hasn't been taken into consideration, but likely soon it will be another common addition.

You don’t need to imagine since even in Europe the majority of boilers/water heaters are electric they are just not heat pumps which makes them much less efficient.

Many buildings do not have a gas supply and many cities in Europe do not have metropolitan gas network at all.

Resistive loads are at best 100% efficient, your average heat pump is about 300% efficient.

Italy at least the southern parts of it and some other countries like Spain for example can probably transfer to a passive thermosolar water heating system like Israel uses.

TBH I’m not sure why it’s not more common around the world it’s cheap and fast it’s nothing more than a frame with some pipes in it covered by a pane of non-IR blocking glass.

Which European countries are majority electric-boiler, out of interest? That claim surprised me, but I'd believe it with some references.

Here in the UK, I haven't seen an electric boiler for decades. Most gas boilers have an electric immersion backup for hot water, but that's it.

In scandinavia, there exists almost only electric and heat-pump boilers.

Denser metropolitan areas have "district heating", which means water-transported heat that can be generated remotely by boilers, but there are also heat-pumps on these networks. For example, buildings can "sell" heat into the network with heat-pumps. Data centers do this.

Thank you - district heating looks like a great topic to learn more about; I hadn't really considered that the same principles behind feeding back into the (electric) energy grid could apply for thermal energy too.

technically, electric heaters are nearly 100% efficient at turning the electric energy to heat energy.

Heat pumps can be 300% efficient.

Well the article is specific about replacing gas boilers with heat pumps, of course where the boiler is already electric there is not this issue (or it is marginal).

BTW AFAIK those thermosolar thingies used in Israel are quite good but they - at least the ones I am familiar with, common in Tunisia also - have anyway a supplemental electric resistance and are anyway only suited to self standing homes or very small condo's that have a flat (terrace) roof.

And anyway in the same hypothetical 24 flat condo, 6 floors by 4 flats, you would need 48 pipes + 24 electric ducts going to the roof, but most lower floors flats (first, second or third floor, maybe also fourth) would be too far away so you would need a third pipe (24 of them) for circulating the hot water, and of course 24 pumps.

And of course the climate in Israel or Tunisia can be compared to only some extremely southern regions of Italy and Spain.

(worth noting for comparison that electric showers can consume 10 kW, albeit for short periods of time)

It seems like there's a risk of infrastructure inequality appearing, with high-quality, low-emissions (and perhaps also cheaper) energy consumption for people living in modern and/or well-equipped neighbourhoods, and dirtier energy sources as the distance from those areas increases.

Are there ways to create regulatory-level incentives for the benefits of clean energy consumption to feed back to other regions?

Electrical systems are going to need to be upgraded for sure. At the current rate of warming, even without trying to be more environmentally friendly (so replacing gas with electric heating and electric cars), we'll probably see significantly increased air conditioning use, which may impact sizing of electrical systems as well.

UK retail electricity has suddenly risen from about 12p a kw to 18p. So even if you achieve a real world COP ratio of 3x you will be paying twice the price of mains gas and a little more than oil. Ironically this is partly due to a levy to fund green subsidies that seems to apply to electricity but not gas? I'm not sure people have factored this in yet, if electricity does not come down in price it rather ruins heat pump economics.

The other mystery is why we still buy night storage heaters not mini split air conditioners? Do they not work?

Few domestic buildings in the UK have the space to install the huge and noisy air conditioning fan required, never mind the insulated piping to get the heat into the house.

It's a nice idea, but the reality is that most people will end up heating their water with a good old immersion heater.

See https://youtu.be/GhAKMAcmJFg

The real problem is our buildings are badly built and insulated - and the new ones just aren't good enough.

Reply on news.ycombinator.com