Honeywell Evohome - Off, but on

In May we had a (brief) period where the weather was fantastic, and I decided to turn the central heating off using the Quick Action on the Evohome controller. It was then a bit of a surprise to feel that a couple of radiators were still being turned on, confirmed by the green light on the BDR91 wireless relay in the airing cupboard.

After a bit of internet searching I came across this Knowledge Article from 2018 on the Honeywell Support website:

https://ensupport.getconnected.honeywellhome.com/s/article/The-evohome-controller-and-radiators-are-in-off-setting-but-the-boiler-continues-to-fire?language=en_US

It appears the two main reasons in the list that applied to us were a) weak batteries and b) loose adaptors. A couple of the HR92 TRVs had been knocked, and so weren't tight to their valve adaptors, which meant that they couldn't completely shut the valve. And my experiment using rechargeable batteries in the HR92s was causing me more work in comms faults and recharging them than it was saving me in money.

So I've gone around and changed all of the HR92 batteries back to non-rechargeable alkaline batteries, as well as the two AA batteries in the CS92 storage cylinder water temperature sensor. I bought a pack of 50 Duracell Industrial AA batteries from Amazon, working out at less than 32p per battery. There's no mAh capacity rating on the batteries or packaging, so we'll have to see how long they last.

Electric Vehicles

There's been a lot of press recently, created by the UK government's policy to prohibit the sale of new petrol and diesel cars from 2040, about the inability of the country's power infrastructure to support a nation's worth of electric cars. Putting aside for one moment that it will likely be sometime between 2050 and 2060 before the last of the new petrol or diesel cars sold in 2040 are no longer in regular use, we still have at least 23 years to come up with a reliable power infrastructure to support widespread EV adoption. Personally I don't think this is a major issue, especially when there's a deadline to galvanise efforts. Also, given that we already have the solutions, in my opinion it is just a case of implementing them at scale.

The first thing to consider is the generation of sufficient electricity for all these additional EVs. Some analysts have calculated that there is a need for handful of new nuclear power stations to cope with the extra demand for electricity. This is based on an assumption of a high peak load when everyone tries to charge their cars simultaneously. Whereas, if every car had a sibling storage battery from which the car was charged, the challenge becomes charging the storage batteries rather than the cars. This is significantly easier, as the storage batteries are always connected, and a simple load balancing algorithm would spread the load on the grid. Ensure that the storage battery has twice the capacity of the EV battery, and you can charge the storage battery at any time of the day or night. This technology already exists, under the banner of Demand Side Management, so if every household across the country had a storage battery tomorrow, the grid would continue to work just fine.

For sure millions of EVs will require more electrical power than is currently generated. And localised micro power generation is a potential solution for this additional power. Even in the northern latitudes of the UK during winter there is solar energy to be obtained from roof top PV panels. When the likes of Ikea can sell you PV panels and a storage battery for a few thousand pounds, you can be sure this is a mature, proven technology. There is still a major need for a country-wide power grid though, as solar and other renewable energies are not evenly distributed. But considering the vast storage battery capacity now available from the paragraph above, the contribution of renewable energy can now be significantly higher than fossil or nuclear. In theory, with sufficient storage capacity, there is no reason why all the country's energy cannot come from renewable sources.

But where are all these batteries going to come from? Are there sufficient rare-earth metals to produce them. This is another bit of scare mongering that has made the mainstream media, perpetuated by journalists that can't even fact check on Wikipedia. For starters rare-earth metals are not rare, as in scarce, but are rare, as in not found conveniently in seams of ore. This does make them more expensive to extract, but also makes them easier to find, because they are pretty much everywhere. Secondly, rare-earth metals aren't widely used in batteries, so there's no need to extract large quantities of these plentiful metals to build batteries. Rare-earth metals are used in electric motors though. But the good thing about that is that electric motors are about the simplest mechanical system you can build, and are extremely reliable. Essentially the electric motor in today's EV is maintenance free for life.

So far my thoughts have been based on the state of current technology. Imagine the world 23 years ago, and now think forward 23 years, noting that the rate of technological development is accelerating. Electric motors and EVs will be more efficient, requiring less energy. Batteries will have higher energy density and charge faster. Micro generation of solar energy will be widespread, as will macro generation from wind, wave and tidal sources. If anything, having stored energy distributed widely around the country will given us a more resilient and robust power infrastructure, not the frail brown-out prone grid the mainstream media portrays.