Storage - A Bonus Technology

My first encounter with storage was whilst working as a paint sprayer and shot blaster in a factory using batch production.  The shot blasting part of the job involved hanging on to a hose gushing compressed air and ground up cast iron whilst wearing a rubber suit in a steel booth.  The compressor was too small to power the blaster alone, so it charged up a pneumatic accumulator which took an hour or more to fill and provided enough air for ten to fifteen minutes blasting, which is about as long as you want to wear a rubber suit.  This fitted in well with the other production tasks because it generally took an hour to organise the work, engage in an exchange abuse with the welding station upstream and drink milk.  The Factory Act required that the blaster/painter was to be supplied with one/two pints of milk per day, this was a form of discrimination against vegans.  A critical part of the job was managing the accumulator because blasting and painting were at the end of the production process a lack of planning could put the weekly bonus in danger.  This was the dirtiest job I've ever had, but it paid well and gave me the funds to go to college, so I'm deeply grateful for it.

The next encounter was more analytical and was related to offshore oil production.  It was an attempt to derive a relationship between crude oil storage volume and loss of offshore production due to bad weather.  Small offshore oilfields which are remote from a pipeline are often developed using a drilling/production platform which exports its oil to a tanker moored to a nearby buoy.  In calm waters, production is more or less continuous, there is a brief shutdown whilst the full tanker is disconnected from the buoy and and an empty one takes its place.  However, in harsh environments where the wave height can be too high  to allow safe operation, the tanker has to disconnect in rough seas and stand off until the weather improves.  Introducing an element of storage into the system allows the platform to continue production when it would otherwise have had to shut down.  The sketch shows the main elements of the system.

By combining wave height data collected from offshore buoys in the region with the operating limits of the mooring buoy it is possible to suggest a relationship between the storage volume and production lost due to bad weather.  This in turn can be combined with estimates of the incremental cost of storage to keep an economist off the streets  for a considerable time.

Storage is a key element in sustainable energy system, wind and solar are non-continuous resources and it is desirable to be able to store energy when it is available but not necessarily wanted.  The classic example is using a battery to store the yield from solar panels for use in lighting the house after sunset.  In the UK the peak demand for electricity occurs early evening in winter, this drops off after midnight, even a relatively small volume of storage, say, less than 5 kwh/household would smooth out demand and ease the integration of wind and solar resources.  At present, the government is providing a subsidy of £5,000 to the buyers of electric cars (storage on wheels), I'm reluctant to criticise anything that might have an environmental benefit, but it would be an interesting exercise to consider what the benefits would be to providing support for storage in commercial and domestic buildings (storage without wheels).  If done carefully, this to, could act to stimulate industry.

I'm maybe stretching a point with this analogy, but the concept of domestic energy storage is not new.  Many Victorian and Edwardian houses had some form of coal storage, traces of which can be still be seen, especially on the streets of London where manhole covers like this are still visible.

The designs can be elaborate with the maker's name worked into the artwork, sometimes with a patent number.  Now the space below the manhole is most likely to be used as a kitchen or utility room, but at the time the house was built it might have looked like this:

Depending on the size of the house, the coal store might have held between one and five tons of fuel.  This form of heating required the householder to be aware of the seasons, coal would be cheaper during the summer, but in winter when all the open fires were in use, the price would rise, so the prudent housewife would want to start the winter with a good stock.

Alongside the coal store in a cool part of the house, there might also be food store or larder.  Not every pre-war housewife dedicated August and September to jam making, bottling and preserving the harvest from the garden, but these seasonal activities were lurking somewhere in the culture.