# Lumps of Coal

​How many equivalent lumps of coal are your energy needs each day? And, how much actual work is that? These were some of the questions raised during discussions at EnergyLab this week. Reasonable questions. Possibly rhetorical. Do engineers understand rhetorical?

If I lift a 10 liter bucket of water off the ground and put it on a table 1 meter high, I give that bucket 100 joules of energy. Repeat that every second and I’m putting in 100 watts of work. After 10 hours, I’ve imparted one whole kilowatt-hour of energy into 36,000 buckets of water.

How much would I have to pay you to lift 10kg (liter) buckets of water every second for 10 hours? Someone suggested \$5,000. Fair enough. At minimum wage you’re at least up for \$150. So how much do we actually pay for that amount of electrical energy to come out of an electrical outlet? ……. 25 cents. One kilowatt-hour of electricity costs 25c.

Most of our electricity is produced in coal fired power stations. That coal gets mined, transported, fired in a boiler that spins a turbine connected to a generator feeding an electrical grid connected to your house to do those ten hours of back breaking labor for one eighth the cost of an iPhone fart app ……. (2 bucks, so I’m told).

The average Australian uses about 10 kilowatt-hours to run all the lights and appliances in their home (30-40kWh per household). If that same person drives an electric car 30km per day for work they’d use at least another 6 kiIlowatt-hours.

16 kilowatt-hours of electricity could be cleanly generated in Australia by 4,000 watts of optimally installed solar panels. That’s fourteen, 2 meter by 1 meter, 300 watt panels – the big ‘uns. Call it 20 to account for intermittency (cloudy days).

20 panels per person to cleanly generate the amount of energy for just their home and car each day. We’re going to need more solar panels. If only our houses were designed to have them mounted anywhere and everywhere at the cheapest possible price. Y’know, without scaffolding and expensive subframes etc….if only.

As for coal? 16 kilowatt-hours of daily energy could be supplied with 8kg of coal. Or, you can lift half a million buckets of water…… I say go the panels.

Posted on April 22, 2017 in Energy & Evolution