Observing the renewable energy transition from a European perspective

Archive for the category “space heating”

Seasonal Storage of Heat in Sand

YouTube text:

The world’s first fully working “sand battery”, which can store green power for months at a time, has been installed by Finnish researchers. The developers said this could solve the problem of year-round supply, a major issue for green energy. Using low-grade sand, the device is charged up with heat made from cheap electricity from solar or wind. The sand stores the heat at around 500C, which can then warm homes in winter when energy is more expensive.

Heat Pump Obligatory in the Netherlands in 2026


As of 2026, it will be forbidden in the Netherlands to install a new gas-based space heater/boiler. Instead, choosing from one of the following three options will be obliged:

1. hybrid heat pump
2. electrical heat pump
3. district heating

Note that this new rule only applies for cases where an old installation needs to be replaced by a new one.

[] – Vanaf 2026 hybride warmtepomp of variant verplicht bij vervanging cv-ketel
[] – Hybride warmtepomp vanaf 2026 verplicht bij vervanging cv-ketel

RIFT Iron Fuel Technology

It began with a student club of my Alma Mater, the Technical University of Eindhoven, known as TeamSolid. They investigated the possibility of a fuel cycle based on iron. Put simple: iron powder is burned, generating energy in the form of heat, the powder turns into rust, which can be reduced (stripped of oxygen) in a process powered by (notorious intermittent) renewable electricity. Repeat cycle. The iron powder can be burned at will, et voilà, you have solved your renewable energy storage problem. The efforts of TeamSolid peaked in installing a 100 kW installation for a local beer brewer:

Apparently, a spin-off called RIFT (Renewable Iron Fuel Technology) and based on the campus of the TUE, has picked up the technology in order to develop it further. First exploit: a project in cooperation with district heating company Ennatuurlijk, concerning 500 households in the city of Helmond that are going to be heated with iron. For that purpose, a new 1 MW boiler is developed by RIFT.

For the longer term, RIFT intends to build a 5 MW iron fuel power plant.

To that end, a letter of intent has already been signed for a collaboration with Veolia Industrial Services. “With the current one-megawatt pilot, we are studying the most important components of the plant in a commercial environment. After that, we can further optimize the system and scale it up to the five-megawatt system.”

The reduction of burned iron powder will take place at the Energy Demo Field of Connectr in Arnhem.

[] – 500 households are warm thanks to ‘rechargeable’ iron powder
[] – RIFT corporate site
[] – Project site
[] – TU/e demonstrates iron fuel at brewery Bavaria: a new circular and CO2-free fuel for the industry
[] – Ennatuurlijk corporate site

[deepresource] – Iron Powder as a Fuel
[deepresource] – TU-Eindhoven Gets Grant to Further Develop Metal Fuels
[deepresource] – Metal Fuel Gets a Subsidy Boost

Read more…


Electro-wired trouser and vest cost about 100 euro. They arrived from China after 6 weeks, after I got a warning of delays due to excessive demand.

Last November, I executed an experiment in bringing down natural gas consumption and stay warm regardless. A report about that exercise here:

[deepresource] – One Month Without Natural Gas Central Heating

The essence of the solution was to create a small corner in your home, around your desk, next to a large window, with a thick curtain dividing the living room in a large 22 m2 and a small 8 m2 part. The latter was kept sufficiently warm with 1-2 300 Watt infrared panels, one under the desk, the other one on the desk for the legs and the other for direct radiation of the upper body.

But with more severe energy shortages looming in the wake of the Ukraine crisis, I tried to see if I could go even further. Preliminary result: it is possible to stay warm on a budget of ca. 6 euro cent per day (0.26 kWh), if you reduce your goals from keeping your house warm to merely keeping your body warm.

That’s where electro-wired clothing comes in, see pictures at the top and below:

The 2 red circles indicate the position of the 2 batteries and 2 buttons, that light up in color. Repeatedly pressing the button iterates through 5 degrees of heating. After a while, the first red position gets too hot.

A day has 16 hours. A single powerbank charge lasts ca. 4 hours, so that would make 8 charges per day times 33 Wh = 0.26 kWh. In the Netherlands, that’s about 6 euro cent per day electricity cost or 2 euro per month!

This solution is perfect for very poor people or people that have been disconnected from the natural gas grid for not paying their bills. Or for well-off people like me (or you), who anticipate that the energy situation in Europe could go terribly wrong in the wake of an escalating crisis over Ukraine, the Gulf, Korea and Taiwan (“WW3”).

[] – TENGOO Smart Heated Underwear Set Phone APP Control Winter Heating Suit USB Recharging Heated Thermal Tops Pants Winter Set

In order for this to work, you need 4 powerbanks: 2 for keeping you warm for perhaps 3-4 hours, while the other 2 are recharging. The silver one I bought a few years ago at an airport for ca. 80 euro, the 2 red ones from HAMA with 10.000 mAh capacity, I bought yesterday for 20 euro each; capacity 33 Wh.

Vertically Mounted Solar Panels

Everyone usually places the solar panels flat on roofs. But researchers at Hanze University of Applied Sciences Groningen have found that erect (vertical) installation of solar panels is much more attractive. A vertically installed solar panel ensures a more even production of electricity over the year. And as a result, a vertical solar panel puts less strain on the energy network. This is apparent from a test set-up that has been extensively tested at EnTranCe | Center of Expertise Energy, part of the Hanze University of Applied Sciences Groningen… The yield of a vertical panel is almost the same in winter and sometimes even higher. In the summer months, the yield is lower and therefore returns less to the energy network. This yield fits better with the consumption pattern of electricity and thus reduces the load on the energy network.

Enough reasons to also promote the arrangement of panels in this way. This is apparent from the research that researchers … of the Hanze University of Applied Sciences Groningen. In the test set-up, both set-ups, vertical and at an angle of 35 degrees to the south, were tested over a period of 8 months.

When we think of installing solar panels, we usually think of solar panels on a pitched roof. Unfortunately, not everyone has a usable roof. Everyone has a usable facade to attach solar panels to. A vertically installed panel produces 70% of the electricity per year compared to a panel installed at an angle of 35 degrees. This means that a panel on the roof at an angle of 35 degrees ultimately yields more, but also has to supply more back to the energy network. This often causes overloading of the network and can be prevented by the vertically arranged panels. (Google Translate)

[] – Oplossing Hanzehogeschool Groningen: Verticaal opgestelde zonnepanelen beter voor energienetwerk

This is exactly what I want to hear, with my “energy wall” ambitions. The 30-year-old garden fence needs to be replaced anyway, so replace it with a robust wooden fence of ca. 1500 euro, next screw 10 matte-black solar panels vertically against the fence and cover these solar panels with 10 double-glazed panels in a click-system, leaving a few cm space between solar and glass panels of 100 x 160 cm each, resulting in a sort of PVT-system, with hot air as medium. Use a ventilator as air pump and create a closed-circuit via a large isolated volume (1 m3?) of gravel or pebbles as heat storage and create a second closed loop through the same storage and living room. With an estimated efficiency of 40-60% and a surface area of 16 m2, that would still amount to 8 kWh/day heat on average during the darkest month December and 1.3-2.5-5.0 times as much in the heating months January/November, February/October and March/September respectively.

Annual solar radiation in the Netherlands.

During the Summer, the glass (or polycarbonate) panels can be removed to avoid overheating, hence the required click-system.

[] – Solar thermal collector
[] – Photovoltaic thermal hybrid solar collector

Note that the yields of vertically mounted solar panels/collectors can be significantly increased by placing horizontal mirrors at the feet of the panels/collectors:

Read more…

One Month Without Natural Gas Central Heating

Infrared thermal panel, 300 Watt, 60 x 50 x 1 cm, cost 80 euro, excl. delivery. Manufacturer: Koenighaus, Emmerich, Germany, but there are many other suppliers.

By the end of October I bought online a 300 Watt infrared panel, with the intent to see if the room thermostat position could be lowered with 1-3 C without loss of comfort, placed it on my desk, next to the two computer monitors in use and leaning against the third unused monitor and was amazed with the thermal comfort it provided.

Shortly after, the temptation arose to see if I could do without natural gas-fueled central heating at all and formulated the following challenge:

  • For the entire month of November, switch off the central heating completely.
  • Minimal gas consumption is allowed for tap water and ultra short shower.
  • I may buy anything to increase thermal comfort, provided it uses no fossil fuel and only modest amounts of electricity.
  • Investments may not cost a lot.
  • Consider the exercise as a preparation for times plagued by fuel shortages, for instance in case of a major conflict between the US and China over Taiwan.

The background of this challenge is that European gas reserves could run on empty, later this winter, especially if this winter is going to be cold, see Reuters link and graph at the bottom of this post [1].

Personal situation: non-vaccinated and hence since today (6-11-2021) completely excluded from Dutch society (minus the super-market). Reason personal refusal vaccins: I am pretty sure I contracted Covid in March 2020 after a holiday in Bulgaria and could fairly easily handle that and am weary to let vaccins interfere with my good health and ditto immune system, especially not with these “head over heels” mRNA garbage, that needs to be “refreshed” every few months or so, a boon maybe for Pfizer c.s., but a considerable risk for the population. I would prefer to not take any vaccine at all, but if that means permanent social exclusion, I’ll settle for the upcoming Novavax/Valneva, more conventional vaccines. The point to make is that this entire winter I’ll be stuck in my home, apart from the daily 1 hour jog in a nearby forest.

My living room of ca. 30 m2 is split in two by a thick curtain, that was installed years ago for energy saving purposes, but so far never used. The smaller part of 10 m2 is where my bureau is and a 4 m2 South-West-facing window, enjoying direct unhindered sunlight as of 11:00. Apart from the infrared panel I have this:

Stoov Big Hug XL“, Utrecht, the Netherlands, very effective and cheap electro-wired body warmer chair cover. Comes with battery and 3 position regulator. Powered by a small laptop-like charger, can’t be consuming much. Only electro-wired clothing would be more effective. It certainly is at least as effective as the infrared panel, due to direct contact with the body. The third position is very warm, which is only comfortable in the first half hour in the morning. Battery + power supply are sufficient to guarantee warmth during the entire day (ca. 8:00-19:00)

Prospects are good. Today, 6-11-2021 was the coldest night so far and until November 20, temperatures won’t be lower. If I can stomach this, I can stomach them all.

Personal daily, as well as cumulative gas and electricity consumption data from November 2020, while in lockdown and at home all day (like in November 2021). Average daily numbers: cost – 5.06 euro, electricity – 5.18 kWh, gas – 4.56 m3 (divide all numbers by 30).

The final number for November 2021, after a month of not using the gas-fueled central heating: 50% less cost than last year, with much higher per unit cost this year.

Same data for November 2021. Average daily numbers: cost – 1.74 euro, electricity – 7.00 kWh, gas – 0.13 m3.

Date T living room T outside Elec. kWh Gas m3
November 2020 average 5.18 4.56
——————— ———— ——— ——
01-11-2021 08:00 xx.x 6.5 6.00 0.33
02-11-2021 08:00 xx.x 2.7 7.00 0.14
03-11-2021 08:00 xx.x 0.1 7.00 0.13
04-11-2021 08:00 xx.x 1.5 8.00 0.31
05-11-2021 08:00 xx.x 1.0 6.00 0.24
06-11-2021 08:00 15.5 5.2 8.00 0.36
07-11-2021 08:00 15.5 10.2 9.00 0.24
08-11-2021 08:00 16.0 6.0 8.00 0.32
09-11-2021 08:00 15.5 3.0 8.00 0.34
10-11-2021 08:00 15.1 1.0 8.00 0.36
11-11-2021 00:00 15.3 4.2 9.00 0.19
12-11-2021 00:00 15.5 1.0 10.00 0.53
13-11-2021 00:00 16.0 8.0 10.00 0.13
14-11-2021 00:00 16.5 8.2 12.00 0.53
15-11-2021 00:00 16.5 7.3 12.00 0.19
16-11-2021 00:00 15.9 5.8 11.00 0.22
17-11-2021 00:00 15.5 5.7 12.00 0.36
18-11-2021 00:00 14.8 5.0 9.00 0.36
19-11-2021 00:00 16.0 10.2 11.00 0.47
20-11-2021 00:00 16.5 8.1 9.00 0.57
21-11-2021 00:00 16.3 8.4 11.00 0.22
22-11-2021 00:00 15.0 1.2 7.00 0.53
23-11-2021 00:00 14.3 3.3 11.00 0.12
24-11-2021 00:00 15.3 3.1 12.00 0.22
25-11-2021 00:00 14.2 3.2 10.00 0.61
26-11-2021 00:00 14.2 4.0 13.00 0.19
27-11-2021 00:00 13.2 0.1 10.00 0.82
28-11-2021 00:00 13.2 2.1 13.00 0.27
29-11-2021 00:00 13.2 0.3 10.00 0.56
30-11-2021 00:00 13.4 5.0 20.00 0.75

(Temperatures in Celsius at dawn = minimum)
Began this challenge and recording as of 6 November and will be completed by the end of that month. Swithing off the central heating completely already occured before November 1.


03-11-2021 – Eventually you will get your bed warm from your own body, nevertheless, without heating it doesn’t go fast enough. So I bought 3 old-fashioned bed jars, 2 rubber ones from the Action for 2.99 euro en one from the HEMA for 19.00. That really solved the problem, 8 hours per day entirely covered, thermally speaking. The cheap ones are better due to their flat shape and stay where they are, the aluminium cylinder gets kicked out of bed during the sleep.

Read more…

Passive Solar Heating

I have a SE-facing 10 x 2.2 m = 22 m2 garden fence, not covered by shade from trees, that in principle could be used as an “energy wall”, consisting of PV-panels, with a double-glass cover, to trap solar radiation and convert it in both electricity and warm air. Over the entire year, the vertical energy wall would not yield optimal energy gain, but the point is that you need energy much more in the winter than in the summer, so the vertical position of the fence matches the low position of the sun during the winter.

This post will contain inspirational ideas from already implemented projects and as such updated regularly.

[source] Average solar irradiation in the Netherlands. In December, it is still 70 Watt/m2 during light hours or 55 MJ/m2 = 15.3 kWh/m2 over the entire month or 0.5 kWh/m2 per day. 22 m2 would correspond to 11 kWh/day solar heat or 1 liter gasoline in December, in February that would be 2.5 liter.

The idea is to build a “box” of 10 m x 2.2 m x 10 cm. Since double glass is cheap and durable in the weather, let’s assume that both sides will consist of double glass

[] – price 2 x 10 m x 2.2 m double glass = ca. 932,- euro. The glass back sheet needs to be a black sheet, like blackened triplex or steel wool mesh, or simply painted glass, details to be decided later, after some thermal modelling and calculations. Alternatively I could replace the old fence with a newer solid one that could act as the back sheet, perhaps with an insulation layer over it.

At a later stage, the back sheet can be covered from the inside with solar pv film panels.

[deepresource] – Solar Air Collectors
[deepresource] – Transpired Solar Collector
[deepresource] – DIY Solar Collector For Domestic Heating

[source] 41 m2 garden fence solar, something like this I have in mind.

The number of hours sunshine in Eindhoven increased significantly over the last 40 years, from 1350 to 1800!

Read more…

Passive Solar Space Heating

[deepresource] – “2226” – Heating with Light, Humans and Devices Only

The Internet is Hot

According to a recent report from KTH Royal Institute of Technology in Sweden, about 10% of the world’s total electricity consumption is currently used by the Internet. The figure has risen from 8% in 2012 and may reach 20% by 2025.

[source] – why we shouldn’t worry about the Internet’s rising electricity consumption

All the electricity that goes into a functioning global IT-system, eventually gets dissipated into heat, heat that the IT-operators need to get rid of. Here lies a massive source of yet largely untapped space heating potential.

Vattenfall Offers High-Temperature Heat Pump


Next year, Vattenfall will bring a new ‘plug-and-play’ high-temperature heat pump onto the market, that is suitable for older homes, eliminating the need to replace conventional radiators with an expensive floor heating. ‘Plug-and-play’ meaning: gas heater out, electric heat pump in. Temperatures: 70-90 C, power 6 kW base, 11 kW peak. The project is a joint-venture between Swedish Vattenfall, Dutch installer Feenstra, German hybrid heating manufacturer SOLVIS and the Japanese DENSO components and heat pump company. The hope is that over the entire season, a COP-value of 3 can be achieved.

The real advantage is that very high investments can be postponed. Vattenfall estimates that 2.8 million Dutch homes (out of 7 million in total) are suitable for this natural gas-free space heating solution. Another advantage is that the solution is available NOW, rather than having to wait for district heating or hydrogen. The medium in the thermodynamic cycle is CO2. The heat pump is rather bulky to accommodate a large water buffer, with stratified storage. The strategy is to slowly heat the storage during the day. When the inhabitants come home in the evening, the house can be warmed rapidly.

The heat pump is the result of 3 years R&D between Vattenfall and Feenstra and implemented in 20 test homes in Heemskerk. The winter of 2020-2021 had fairly cold days, but no complaints were registered.

[] – Vattenfall komt met warmtepomp voor oude woningen
[] – Van het aardgas af zonder ingrijpende verbouwing
[] – Bestaande woningbouw eenvoudig aardgasvrij
[] – Plug and play-warmtepomp voor ‘moeilijke’ huizen productierijp

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