Blogging The Green

I always find discussions of alternative energy for homes or cars interesting.  Not just in themselves but because of what is forgotten.  Energy Storage.  Many people will respond to pollution problems with answers like "I’ll just put up some solar panels and run my home".   They seldom really think about how poorly a system will perform without good energy storage.  Whether in a car, a home power system or a countries power grid, its all about matching energy supply with demand and that means storage.  Even talk of liquid and gas fuels comes down to this.  Fuel is just an extremely efficient storage medium for energy.  Any talk of replacing gasoline in cars really comes down to how efficiently the new power source can store and release energy.

Here’s an obvious example to highlight the basic problem.  If I use solar panels to power my house then obviously most of the electricity is being generated while I’m at work and not using any.  If I have an electric vehicle, which I charge at home, the problem gets even worse, as I’ll be charging it when the sun is down and no power is available.

On the Small Scale

In the case of a single house the obvious answer to this problem is a battery. Actually, quite a few batteries.  Once I have enough however, I can store all that energy generated during the day and release it on demand.  In essence the battery is powering my house and acting as a load balancer, instantly adjusting the amount of power to match the current requirements.  The solar panels  main job is to charge the battery.  In this way you get a even level of electricity instead of wildly fluctuating power based on the whims of nature.

There are a few problems with this.  First and foremost  batteries are ridiculously expensive.  Often they are the most expensive component in any home energy system.  Second, if your reason for going with alternative energy was to save the environment you might want to look a little more closely at your batteries.  A lot of toxic substances are dumped into the environment both through manufacture and disposal/recycling of batteries.

So if you want to avoid the batteries what do you do?  If you are completely off the grid the answer is usually a generator.  Generators have the advantage of being quick to fire up in times of need, just add fuel.  Of course now you’re generating pollution right at your own home which may not sit well with you not to mention the cost of fuel.  If you are off the grid you just have to pick your poison or go without power. (Check out my post on Bixby Energy for a possible alternative in the near future).

If you are like most people though, you are on the grid.  In that case the easiest answer is  just to connect to the electric company in a system called grid intertie.  In this way you use your utility company as a battery.  When you generate too much power for your uses you sell it to the power company and when you need more then you are generating, you buy it back.

On the Grand Scale

So we have passed the buck to the power company, great.  So how do they make sure there is always enough power when you turn on that 60" HD TV?  Unfortunately the utilities have no higher power (excuse the pun) to pass the buck too.  Their job is to now generate enough electricity for the heaviest usage and then find something to do with the excess power when usage levels are low.

Power companies have a few standard ways of dealing with fluctuation also known as load levelling.  First they have their mainline, or Base Load,  power plants, typically coal and Nuclear.  These plants are very expensive to build and maintain but cheap to fuel.  They run these plants full tilt 24/7 because they are economical and their efficiency drops if they are run at less then 100%.  At the other end they have the peak power plants.  Typically these are gas turbine plants which are cheap to build and operate but the fuel is far more expensive.    It makes sense to only use the capacity of these plants when absolutely necessary.  Gas turbine plants play the same part as your diesel generator would at home.  The second method of load levelling is on the demand side.  By lowering the price of power when demand is low, power companies encourage consumers to adjust their consumption habits and help level out power usage.

Even with those techniques a power company can find itself in a temporary jam and not be able to generate enough power to meet demand.  This problem can be thorny enough using nuclear, coal and gas power plants which can run 24/7.  As alternative power sources like solar and wind become more common the problem gets thornier.  When a large chunk of your power is based on when the sun is up or the wind is blowing, estimating your available power gets a tad difficult.  Here is where storage comes in.

Unlike for your home, batteries are not generally the best way to store energy for power companies.  Imagine the size of a battery array that can hold 50 megawatts.  It would be monstrous, fantastically expensive and require very high maintenance.  This is not to say they don’t get used buts its not very common with current technology.  So how does the power company store electricity? Could these same methods be used by you at home?  I’ll cover that in tomorrows post.

Related Posts

• Storing Electricity Complicates Everything - Part 2
• Solar Power through Magnification
• Solar Energy. Mana from heaven?
• Building a Sustainable Home - Part 1
• Why is solar power so inefficient?

Tags:   alternative energy · batteries · Energy Storage · Grid intertie · load balancing · load leveling · power company · solar panels · utility company6 Comments