What is expensive because it requires a lot of electricity?

Answer 1

Desalination

Answer 2

The most expensive is probably solar cells. Wind power is expensive too, compared with fossil fuel power or nuclear, and has to be subsidised to make it practicable as part of a power network. This of course may change in the future if fossil fuels go on getting more expensive due to increased world demand and dwindling reserves.

Solar cells (photo-voltaic) convert sunlight into electricity directly using silicon crystals-these are described as 'poly-crystalline PV panels'. They produce DC current at a low voltage depending how many cells are connected in series but usually at 12v DC. To feed into a normal domestic system this has to be converted to 110v 60 Hz in N America, or 240v 50 Hz in Europe. This requires a piece of electronic kit called an inverter which effectively does the opposite of a rectifier, ie converts DC to AC. Assuming the house is connected to the electricity grid, surplus solar output can be exported, if the electricity supply company runs such a scheme. This is useful as obviously max solar power will be generated in the middle of the day, and not at all at night when max domestic demand usually occurs. An alternative is to have a large lead-cell battery which can be charged at 12v DC directly during the day and used at night. This would be the preferred system if in a remote area without a grid connection.

The drawback of course is the cost of the installation. I only have figures for the UK in 2008. A typical cost of installation of a 2KWp (ie 2KW peak) system given by my electricity company is from (that feared word!) £11,848 (double the figure for US dollars). This includes an inverter but not a battery. In UK conditions this is expected to generate savings in the electricity bill of £175 per annum. There is also in the UK an income of £68 pa from a Renewable Obligation Certificate-but I discount that, it is not a real saving and has to be paid from taxation by other people, it's just an incentive to install the system.

So you are left with spending about £12,000 for an annual saving of £175. Now I rate that as expensive. The payback time comes to 68 years, assuming nothing goes wrong in that time and no maintenance is required. I'm not sure what evidence there is for long time durability of these panels, but I'm sure the manufacturers won't guarantee them for that length of time. Probably 10 years max. In fact no manufacturer can even promise to be in business in 68 years time! So if you go in for such a system it can only be because you are a dedicated 'green', and moreover have deep pockets.

Of course the UK is not noted for abundant sunshine. In Arizona or Australia the situation may be much more favourable, and also in remote places the costs may look different if the alternative is hauling fossil fuel over a long distance to power a diesel engine for example.

Answer 3

Manufacturing in general is expansive because of energy requirements.

The more energy required the greater the expense.

Answer 4

Electric heating, air conditioning, and mining for cryptocurrencies like Bitcoin are expensive because they require a lot of electricity to operate.