The answer is a cabbage!

The day job is messing with some energy management software, sustainable energy presents some inconvenient challenges, but there are some exciting technologies emerging (is it dangerous to use the word exciting when you are sixty one and a half?).  Not least of these is the internet of things.  Historically, energy distribution systems have been configured to supply the peak demand, the underlying assumption being that there is little intelligence in the system beyond thermostats and tariffs such as Economy 7 which encourages the use of off-peak electricity.  We only run the washing machine in the morning, because we've always done it and there is no timer switch.  During the spin part of the cycle, the washing machine draws about 2.5kw for a few minutes.  Taking this to its illogical conclusion, a large pile of dirty socks is causing a spike in demand which in turn causes a gas fired power station to start up.  If the nation did its dirty washing overnight and we might not need the gas fired power station.  If I can control the devices in my home, I can be a nicer energy consumer and possibly hand the task of energy management to my mobile phone.  I have a Raspberry Pi which is running an emulation of a system (not related to the stuff mentioned above), this imaginary system feeds its status to the Pi's web server which can be accessed by my phone.  Maybe one day the Pi and my phone argue about the best time to do the washing, it is the internet of things that lets the the washing machine join in the conversation.

Apart from this blog, I don't advertise my interest in these things.  However, I have spent some time in the garden with a small PV cell and a multimeter observing the effect of clouds on a very small solar device and engaging in other equally bizarre pursuits.  This activity has not gone unnoticed and I occasionally get asked "why don't you have solar panels on your roof?".  This question always comes in summer and generally from people who have PV panels on their roof.  My response is that solar panels at latitude 51N  don't do much during winter when demand for energy is high.  In summer they work well but in winter sun-earth geometry and clouds can take the output down to well below 1 kwh/m2 compared to 8 kwh/m2.  Sustainable solutions need to take into account seasonality, solar panels might let you balance your consumption with generation over the period of a year, but in winter you still need the gas fuelled generators.

Conventional energy businesses have evolved a functional business mode, it's one that works because in the UK when you flick the switch, the lights go on (if they don't, the failure will probably be discussed in the media).  For sustainable systems, maybe agriculture is a better model because it is based on seasonality.  I'm a newbie gardener, but it seems to be that only difference between vegetables and solar panels is one of form and one tastes better than the other. There is a natural rhythm to the gardening year.  You start by planting seeds which will germinate when the soil is cold, like broad beans which will be harvested in late spring or early summer.  Next come plants like tomatoes which need the summer sun to grow.  When the spring and summer vegetables have been cleared, it is time to plant the winter vegetables like cabbage which will grow slowly as the days become shorter.  Thus on this bleak January day, I am going to pick a cabbage for the evening meal and later seek out a book on how to grow them properly, as those from my first attempt are a bit weedy. Part of the process of gardening is storing produce thus jam making hand hydrogen storage have a lot in common.