So let us imagine that a few friends are chatting about the previous year.

One fellow says, “I have a buddy, Bill, who drank 365 beers during the year.” “That’s great,” says Jim, “a beer every evening with dinner is just a great approach to life.”

“But that is not what happened,” replies Allan. “From New Year’s Day to the 10th of January, Bill celebrated wildly and drank 120 beers. When he fell down his front stairs, his family took him off to the Amber Bubbles Rehab Center, where he spent a month.” Bill came out just before Valentine’s Day and went out with friends to celebrate someone’s engagement and drank 18 beers. He was swaying on his feet, so his friends told him that he was far too drunk to drive home and that he should take a bus. Bill agreed, so he staggered out into the night and saw a city bus, with 20 passengers, which pulled up right in front of him.

Bill headed for the bus, but, leaving the engine running, the driver jumped out and ran over to the Chinese takeaway to buy some dinner. Undaunted, Bill climbed into the bus driver’s seat and pulled off. He drove the bus like a NASCAR driver, almost cornering on two wheels. It was the agonized screaming of the passengers which attracted the cops.

An unimpressed judge gave him 30 days in the county jail.

After coming out, Bill got a hotel job as a general handyman and cleaner. That went fine until the manager told him to clean out the cellar — and he did. He drank 36 beers. After he was fired on the spot, Bill’s brother came to fetch him and carried him to the car.

Bill continued drinking at home and with friends, consuming 191 beers over the next two months, until one night he tried to fly from the roof of the pub using polystyrene packaging as wings. He landed on the street power lines, which bounced him gently into the road, but the cables broke, starting a fire which burnt the pub down. The judge gave him eight years in the state pen.

So that is how Bill drank 365 beers in one year. That is very different than one beer a day with dinner for a year.

Comparing quantities

So, you have to be very careful in comparing quantities. The rate of consumption is extremely important.

In a very similar vein to Bill and beer is the consumption of electricity. There is a huge difference between the designations of MW and MWh.

The media get this wrong most of the time.

The MW, or ‘megawatts,’ is the amount of electricity available all of the time. In physics, that figure is known as the power. This means a situation in which electricity is running continuously, or is equivalent to somebody responsibly having one beer a day with dinner.

In contrast, MWh is the total amount of energy, all added up. That is the equivalent of Bill’s beer binges.

When a news item tells you that some energy source produced 500 MWh of electricity over the past few months, you have no idea how it was delivered — most likely like Bill’s beer bar-hopping. They then usually make it far worse by adding a line like, “This is enough to power 1,000 homes.” They don’t say, “in a Bill bar-hopping mode,” they imply continuously. If you want electricity provided to your house, you mean “all of the time, so that I can use it when I like.” This is the power in MW.

What is the nature of the source?

In considering electricity, one has to ask, “What does the original energy source look like?” In the case of solar, it is only available during the daytime, and then only if it does not rain. In the case of wind, it is only available when the wind blows. Furthermore, you get a varying amount depending on how hard it blows. If it blows too hard, the wind turbine activates its brakes so that it does not shake itself to pieces.

In the case of solar, you only get maximum output at lunchtime, and much less, like half, before mid-morning and after mid-afternoon.

If you want to try to get a more even supply from solar or wind, then you have to add extra systems like large batteries. You also can’t use the solar panels to run an electrical system at the same time as charging a battery array. You have to install more solar, typically larger than the original installation, if you want adequate power at breakfast and dinner.

So next time you see a solar marketing picture, which, amusingly, is so often taken when the panels are not working, like at sunset when the dying orange rays are glancing off the panels, then remember Bill’s beer binges and don’t believe that the total energy number, in MWh, is representative of the “power available” number in MW.

You don’t want to be driving the bus; you want to be having a respectable dinner with family or friends.