From Watts Up With That?

Dr. Lars Schernikau: Energy Economist, Commodity Trader, Author (recent book “The Unpopular Truth… about Electricity and the Future of Energy”)

Details inc the full Blog are available at www.unpopular-truth.com

Heat pumps are having a moment. Governments promote them, utilities love them, and they are, now more often than ever, described as an obvious replacement for fossil fuels (oil, coal, gas), fueled heating. The basic idea sounds great…a heat pump works like a reverse refrigerator. Instead of “pushing heat out, it pulls heat in”. That heat can come from the air outside your house or from the ground below it.

The International Energy Agency (IEA) sums up the enthusiasm nicely. “Heat pumps, powered by low‐emissions electricity, are the central technology in the global transition to secure and sustainable heating. Heat pumps currently available on the market are three‐to‐five times more energy efficient than natural gas boilers. That statement contains three big claims:

(1) heat pumps are three to five times more efficient,

(2) they run on “low-emission” electricity, and

(3) they are secure and sustainable

All three deserve a closer look, so here we go…

1.    Why heat pumps really are efficient… at the device level

There is a solid reason, rooted in physics, behind why heat pumps are attractive. Transferring heat from one place to another takes much less energy than generating heat from scratch by burning fuel. Under favorable conditions, a heat pump might use one unit of electricity to move three units of heat. This is where the famous “three to five times more efficiency” number comes from.

But here is the catch! That number is not efficiency in the everyday sense. It’s called the Coefficient of Performance (COP), and COP is not the same thing as system efficiency. To start with, a heat pump relies on electricity, while a gas or oil boiler mostly relies on chemical energy and needs very little electricity to operate. You can keep a boiler running with a small backup battery… but you cannot do that with a heat pump… the three to one number forgets the (in)efficiency of the electricity required from the grid… and you and I know how complex that grid is.

2.Electricity doesn’t just “arrive” for free

The “three to five times more efficiency” claim, quietly assumes that electricity arrives at your home with no losses. But in reality, electricity available 24/7/365 has to be generated, transmitted, balanced, and backed up.

On average, roughly 2.5 to 3 units of primary energy are needed to deliver one unit of electricity to your socket when thermal power plants are involved, as they mostly are.

That means using electricity “100% efficiently” at home starts, at the system level, at only 30 to 40% efficiency. Wind and solar changes the accounting by introducing their own challenges, among them being the need for overbuild, short duration storage, long duration storage, thermal backup and larger and more complex network integration and transmission infrastructure. Once these are considered, wind and solar dominant systems do not outperform coal, gas, or nuclear in net energy efficiency but actually underperform. Think about energy density, intermittency, and the short operational lifetime.

3.Heat pumps struggle when you need them most

Another unpopular truth that raises the temperature… or does it?…

The colder it gets, the more the performance of heat pumps decline.

When winter hits and heating demand peaks, the heat pump performance COP drops. This is especially true for air-source heat pumps as ground-source systems tend to perform a bit better, even though they are more expensive, slow to install, and often impractical in densely populated cities.

This creates a nasty feedback loop… because just as heat pumps need more electricity during cold spells, solar output tends to be low, wind can be unreliable, and grids are already under pressure on top of the dropping COP. In winters coal and gas plants are usually ramped up to secure the electricity supply. So even if your annual electricity mix looks “green,” the marginal power that keeps your heat pump running during a cold snap is more often than not fossil-based… do you see the feedback loop?

4.Peak power is the real bottleneck

Electrifying heating doesn’t just increase electricity consumption; it increases peak power demand in winters when power system is already strained. Grids must be built for the coldest, darkest, calmest winter evenings, not for yearly averages. The IEA projects that peak electricity demand grows far faster than total electricity demand due to heat pumps, electric vehicles, data centers, and AI. When demand spikes, coal, oil, gas and nuclear fill the gap. That is why the idea of heat pumps running on wind and solar often collapses under real winter conditions.

5. Security and sustainability depend on where you live

If you are in rural Scandinavia with abundant hydropower and a very secure grid, heat pumps could make more sense, but in large cities with fragile grids, the picture changes completely. In urban areas, air-source “monoblock” heat pumps are popular because they are cost-effective and easy to install. However, they are noisier, lose efficiency in winter, and are vulnerable during power outages. When the power goes out during freezing weather, circulation stops, water freezes, pipes burst, and systems can be a complete write-off. After some recent winter blackouts (Berlin end December 2025), many heat pumps didn’t come back online even after electricity was restored.

Now imagine there is an armed conflict or cyber-attack? Do you feel safer with a heat pump or with a standard gas- or oil-based boiler?

So let’s be honest…from an energy security standpoint, heat pumps seem flaky. From a sustainability standpoint, powered by energy systems that require massive overbuilding, short lifetimes, and heavy material use it is questionable at best and deserves some skepticism and allot of discussion.

Summary – So where do heat pumps actually fit?

Heat pumps are neither a universal solution nor a dead end. They work best, out in the country, where grids are reliable, electricity is reliable, or where winter temperatures are moderate. But in a city setting, district heating combined with large ground- or water-source heat pumps and thermal storage is likely more appropriate than widespread deployment of individual units.

One last reality check we should consider is that… adoption closely follows subsidies. When subsidies drop, sales drop. That doesn’t make heat pumps bad, but it does suggest they are not the obvious, no-brainer solution they are often made out to be.

Heat pumps are efficient machines, sure, but whether they actually contribute to an efficient, secure, and sustainable energy system depends on too many elements around them. One thing is for sure, heat pumps cannot make oil and gas boilers go extinct… and anyone telling you otherwise is disingenuous.

Read the full analysis here:
https://unpopular-truth.com/2026/02/14/heat-pumps-for-all/