The oil lamp – shining God's light on peak oil

In a previous post on smart meters I raised the issue in passing of what to do with excess power output that may occur from very large penetration of  PV systems on the low voltage grid.  Germany is facing this issue now with wind and solar.  During the working week in summer this is not an issue as German industry (which moans about the cost of electricity) absorbs all the sun power produced. The problem arises at weekends when the 32GWp of installed capacity (at the end of 2012) is operating at anything like full capacity.  Last summer an estimate is that nearly 30GW of electricity was produced from the PV systems making up perhaps 50% of demand.  Surprising although it may seem this is could be a serious issue.  The problem is that if there is excess power on an electricity grid the voltage and grid frequency rise outside defined limits and the grid will shut down. So far the Germans seem to have managed the situation with few outages.  There are a number of solutions briefly covered below to this.  These are;

• Use the excess power yourself.  Not an easy one this if lots of people are off work although as covered in the post linked to on this blog above smart grids and meters could help here by encouraging people to use washing machines and bread makers when electricity is cheap, which it will be when you have loads of it.

• Switch off conventional power stations.  Obviously a whole heap of nuclear, coal and gas power stations are operating continuously providing baseload power.  These can be taken off line (not nuclear since they takes weeks to start back up again).  In fact recently RWE announced the permanent closure of a number of coal fired power stations as the wholesale power price had dropped too low to make them economically viable.  Of course if you go too far down this line you will have insufficient electricity and a grid outage for that reason.  Nevertheless its encouraging renewables are shutting coal down.

• Sell your excess power to your neighbours.  Germany is doing this, despite the nuclear phaseout and the immediate shutting of a number of old reactors Germany is exporting large amounts of electricity and is a net exporter of electricity. However, there are problems with this solution.  First you may find they don’t need it.  Second, the Germans are selling expensively subsidised electricity at a loss to their neighbours.  It should be pointed out that these subsidies for new systems are much lower than they were and phase complete phase out of the FIT at 55GWp of installed capacity (which is only 2-3 years away) is planned.

• Store the excess power.  Germany is building more pumped storage, but obviously this can only be a partial solution.

• With PV systems being the problem, could they be the solution?  A number of solutions present themselves at the micro-generation scale.  Firstly, the individual householder could be encouraged to store electricity and use it at night.  The Germans are being encouraged to do this with a subsidy of some type, although uptake has been low.  Second, the PV inverters which convert DC from the PV to AC for home or grid use monitor the grid conditions.  In fact this is part of the problem.  Say its a dull day in July and the sun comes out and PV is suddenly producing 50% of the electrical supply.  The voltage rises and takes its outside the voltage limits set by the German government for PV inverters.  Millions of inverters shut down but not before you have taken base coal fired power baseload generation off line.  You go from feast to famine in minutes and have an outage.  However, you can by regulation use this grid monitoring facility to aid this control of the grid in a number of different ways.  You can set the inverter to trim its power output (lower its efficiency) when the grid conditions reach a certain voltage or frequency and switch off at a higher frequency (50.2Hz).  This is what the Germans have done.  Another thing they are doing I understand is trying to encourage PV system installation on west facing roofs to spread the peak output over the day.  Another strategy I would suggest is that inverters have different cut-off settings.  So for example in the north of Germany the voltage and frequency settings are set higher than say in Bavaria where its sunnier.  This means not all inverters cut power or cut at the same point and people in Northern Germany are not losing as much money.

There is no doubt that excessive renewables production is a challenge, but one that is not unmanageable with probably all the strategies above required in combination.  Since conventional fuels are finite we will have to cope with this problem at some point in the future. Other countries need to think about this.  There is an estimate that in July the UK got 2.5% of its electricity from PV over 24 hours and about 6% at around midday.  We are way behind Germany but we don’t need as much PV installed for us to catch up.

Neil

Forgot wind turbines and even fracking, the latest controversy set to hit the energy world is smart meters.  The UK has one of the largest programmes of smart meter installation in the world.  The news was this week that the programme has been delayed by a year.  Not the first such delay I believe and being cynical not the last.

Before we get to the controversy, what are these devices meant to do?  As we said in our book smart meters are meant to “monitor total energy consumption in real time and predict and manage trends.”.  We wrote about smart meters in the context of smart grids and devices.  The flow of electricity in the future will be a two-way flow between
consumers and the grid (with most consumers having micro-generation fitted).  The price of power will vary greatly depending on demand and consumers will use smart devices such as washing machines which spread the load by switching themselves on when the electricity is plentiful and cheap. (British Gas are encouraging their customers to do this now as they start to fit smart meters).  With a very high penetration of micro-generation controlling the grid will become that much more difficult as the Germans are finding with over 30GWp of PV installed.  On workdays the problem is not so difficult, but on weekends the very high PV output is providing up to 50% of Germany’s power in summer.  This could lead ironically to grid shut-down as two things happen if there is an excess of power (the grid frequency and voltage rise).  Both of these have to operate within set limits otherwise electronic devices using the power can be damaged.  There are a number of technical solutions to this problem but it would be easy to manage with smart meters.

These would send data to the grid management utility periodically, say every 30 minutes, telling them how much power you are using and if you generate how much you are producing.  A display would tell you this, also how much you are paying for any imported power (and presumably exported power) as well.  They would obviously do away with the demand for meter readers as well, which is why the utilities are so keen on them.  They should allow users to save energy.

The controversy is as follows.  Firstly,  of course cost.  Someone has to pay for this and the consumer will have to foot the bill through increased electricity and gas charges (they will measure gas use as well).  The cost is somewhere between £100-300 per person.  The idea is that smart meters should save the user money although the kind of savings being talked about are small, so will take many years to be recouped by the user-although this is at today’s power prices.

The second controversy is over privacy and security.  There are a number of aspects to this.   Your utility will learn a lot about how you use energy (and try to sell you services on the back of this data).  So will will anyone else who can hack into or intercept your data.  Of course people will be able to tell when you are sleeping or out.  There are supposed to be cases in Germany of people whose houses have been robbed due to thieves getting their hands on this data. The last issue is that of cyber security.  A number of states have already been implicated in cyber attacks and there are concerns that hackers could completely shut down the grid by switching the meters off remotely.

I personally feel that these concerns are overblown or with good design can be removed completely.  On the issue of your power company knowing your energy use pattern.  So what.  They can only guess at what you are up to.  With 22 million smart meters or how ever many there will be (this number does not include businesses) thieves are unlikely to choose you.  This can also be designed out.  Currently smart meters use 4G phone technology to transmit the data.  If power-line transfer technology* was used instead then hackers would find it very much more difficult to intercept the transmissions at source.  They would have to hack the utility which they could do now.  This would also overcome the problem British Gas seem to be having when they turn up to fit a meter and find there is 4g coverage.  The problem with shut down by hackers is due to the utilities wanting to cut non-payers off remotely.  Firstly, I would say people who cannot pay should not be cut off and they should be more humane ways of dealing with this (renegotiating payment comes to mind).  But if this has to be done why not cut-off to be done by someone coming around with a key which allows them to turn a switch?

Despite the concerns I still think that smart meters have too many advantages over grid management and energy conservation to be ruled out.  Most of these concerns could be mitigated with some thoughtful design.

*uses a frequency very different from 50Hz mains to transmit a signal along a power cable (say 600Hz), this has no effect on electrical equipment used to 50Hz.

Neil