This new book from Saul Griffith is a call to electrify our world. In this chapter he shows why it makes sense to make the switch in everything from our heating and cooling, to cooking, cars and even industry. Following is a lightly edited excerpt from one of the chapters.
If you only read one chapter in this book, this is the one I’d have you read. The future is electric. Increasingly, academia is reaching this conclusion, fundamentally because physics and thermodynamics show that it is a good idea. Australia needs to hear this message loud and clear lest we be delayed by the promises of false solutions. Our energy-related emissions require us to make an enormous commitment to electrification as the national strategy, and to make it now.
Thermodynamics and high-school physics
You may remember your high-school physics teacher muttering something about the “laws of physics”. The most famous of those laws are the laws of thermodynamics. There are three big ones that are worth remembering.
- You can’t win; you can only break even (meaning no free energy)
- You can only break even at absolute zero (it’s hard to convert between energy types efficiently)
- You can’t reach absolute zero (even getting close to winning is impossible)
Of course, these are informal translations of the laws. The point is, converting energy from one source to another is a losing proposition because it is inefficient. The first law says your Uncle Jack can’t build a perpetual motion machine out of baling wire and tinnies that will keep the country running on “free energy”.
Whenever you are converting energy from one form to another, you are flirting with these laws.
When we burn fossil fuels to create electricity, we are converting chemical energy into heat, the heat into motion, and the motion into electricity.
That’s a lot of conversions and each conversion is imperfect, meaning we lose some energy each time. These laws, especially the second, explain why electricity is a fundamentally better type of energy to do the things we need to do.
When we burn fossil fuels, we run up against the second law, and more specifically a principle known as Carnot efficiency.
Sadi Carnot, considered the father of thermodynamics, was a French physicist who improved the efficiency of steam engines.
He demonstrated that efficiency was determined by the difference in temperature between the hot and cold sides of the engine. Even if you don’t lose any energy to friction or other mechanical factors, you can’t get all the energy out of the fuels.
In practice, this translates to hard limits on the efficiency of engines. A small car engine might be 20–25 per cent efficient, a truck maybe 30 per cent.
A coal-fired power plant generating steam struggles to get above 40 per cent and very often operates at only 25 per cent.
When electricity is harnessed from the wind, we don’t have these combustion losses and 95 per cent of the energy generated can be used to fill batteries, run motors, power lights or heat water and air.
Starting with wind or solar and using that to generate electricity is the secret to saving huge amounts of energy. The Australian economy can run on far less energy if we embrace the electrification of everything.
In this chapter, I’ll outline what this might look like for a range of technologies, from cars to cooktops to the wider national economy.
Electrifying our vehicles
Electric vehicles are approximately three and a half times more efficient in converting energy into motion than their internal combustion engine (ICE) counterparts. This is because there is no engine throwing away 80 per cent or so of the energy in the fuel and converting it into heat. That heat loss is why you can throw a pot under the bonnet of a Land Rover and cook a stew as you drive – there is a ton of wasted energy.
5.1: Most cars today waste 75 per cent of the energy in petrol. We could use heroic efforts to make them a bit more efficient – or we could electrify the vehicle, use energy from wind or solar, and reduce our energy needs to a third or less.
The battery in an electric vehicle weighs more, but the motor is around 95 per cent efficient, and the motor is lighter than the ICE engine. Most electric cars only have one “gear” because the motor has high torque at all speeds.
This eliminates the need for a transmission, which is another source of waste (and weight) with an ICE. Finally, with an electric car you can do regenerative braking, which captures quite a lot of the energy that would otherwise be warming your brake disks, and recharges the battery.
This situation is most clearly described in Figure 5.1, which captures the trend regardless of the vehicle type. Some people will argue until they are blue in the face that big or long-distance trucks will never be electrified, but they will be.
Truck drivers can’t safely drive for more than 12 hours a day.
That’s two six-hour stints of 600 kilometres each if they drive at the speed limit.
That’s already achievable using today’s batteries, and you have to remember that batteries are getting better and cheaper. We will likely build dedicated charging infrastructure for these vehicles.
Electrification of space heating
5.2: Conventional space heating using gas heaters, bar heaters, fireplaces, etc. can be made more efficient by small amounts, but electric heat pumps (reverse-cycle air-conditioners) are already about three to four times as efficient.
There are four main types of space heating: natural gas, electric- resistance heating (bar heaters), wood fires and electric reverse-cycle air-conditioners (heat pumps). Natural gas heating has an efficiency of approximately 0.9, meaning each energy unit of 0.9 units of heat.
Electric resistance heating has a slightly better efficiency of approximately 0.95. Wood fires have an efficiency of approximately 0.75, converting one unit of energy in a log to 0.75 units of heat in a room.
Finally, reverse-cycle airconditioners have an approximate efficiency of a whopping 3.8 in the average Australian climate.
This gives us an odd comparative graph of efficiencies, as shown in Figure 5.2. An existing gas heater is 90 per cent efficient and might be made slightly more so, but a heat pump uses less than one third of the energy to harness the same amount of heat and deliver it to your building.
Electrification of water heating
5.3: Conventional water-heating with gas or electric resistance can be made more efficient by small amounts, but electric heat-pump water heaters are already around three to four times as efficient with the same heating result.
Hot showers are important to just about everyone at this point, and many of us don’t mind warm water for scrubbing our germ-exposed hands either. Just as with space heating, heating water for these uses is “low-temperature heat”, a fairly unscientific way of describing water below boiling point and amenable to being supplied by a heat pump.
The same efficiencies apply as for space heating. The winner, once again, is heat pumps, which in effect are 300–400 per cent “efficient”, meaning they use a third to a quarter of the energy to heat the same amount of water.
I insulated a hot-tub in my backyard in Wollongong and heat it with a heat pump: when my solar is making more energy than I can use, I dump it into the tub for a relaxing after-dinner soak.
Some people might point out that you can use solar to heat water directly in Australia. The Solahart brand has been a favourite technology for years.
It is about 80 per cent efficient in converting sunlight into hot water, which, because solar is 20 per cent efficient at producing electricity and heat pumps are 400 per cent efficient at making heat from that electricity, is about the same as using solar panels and a heat pump. I just know some grumpy old engineers are going to contact me about this, and I look forward to it.
Electrification of cooking
5.4: In heating a pot of water with a natural-gas burner, 70 per cent or so of the energy is lost as heat. This is far less for electric resistance stovetops, and even less again for electric induction stovetops.
Cooking with gas is much less efficient than cooking with electricity. A gas stovetop has an approximate efficiency of 0.3, and an electric resistive stovetop has an efficiency of 0.7, or even higher for electric induction stovetops.
When you heat a pot of water with a natural-gas burner, 90 per cent or more of the energy in the natural gas gets converted to heat, but 70 per cent or so of that energy is lost because it heats the kitchen or room, not the water.
You can feel this energy in the kitchen if you have been cooking for a while. You can feel the heat escaping from underneath the pot and under the sides.
Electric resistance is better, because the heat is more directly transferred to the pot, and is often 70 per cent efficient, twice as good as gas.
Induction burners are the miracle new technology using the mysterious powers of magnetic fields to heat the pot, not the room. These are as high as 90 per cent efficient at turning electricity into boiling water and in every way are a better cooking experience than cooking with gas – faster to heat, more control, easier to clean, cooler kitchen, lower burn risks for children, cleaner air for the whole family.
Making electricity, not heat
Today we make most of our electricity with coal or natural gas. This is the source of the largest energy losses in the Australian energy system. You can thank that damned second law, and the fact that most of the energy escapes as heat and isn’t converted to electricity.
Making all our electricity with wind, hydro and solar would eliminate the 60–70 per cent of waste energy involved in generating electricity the silly way we do it today by burning rocks.
The cooling towers from the coal or natural-gas electricity generation plant [show] the wasted heat escaping into the atmosphere, not making electricity. There is no such waste with the solar panels and wind turbines on the right.
Perhaps you are seeing the trend here. Despite decades of being told to be more efficient, what we should have been told is to be more electric.
People think industry is going to be so hard to electrify, but it needn’t be. Industry has a lot in common with the examples we’ve just discussed. Industry moves things around, which will be more efficient when electrified.
It heats a lot of stuff up, to low temperatures and to high temperatures, both of which would be more efficiently done using electric heat pumps and induction heating. Electrochemistry is replacing a lot of traditional industrial processes, including in making steel and other metals. This is lowering the energy used in these intensive industries and making industry more productive.
Electrifying the Australian economy
As simple as these examples are, they capture the essence of what there is to win with electrification: a much more effective economy. Economists measure this and call it energy productivity – a measure of the economic benefit we receive from each unit of energy we use. Nations have tried for decades to get a little bit more productive, but we can pretty much see we are going to double our effectiveness by electrifying.
You can use these simple rules of thumb to advocate for electrification:
- Making electricity with wind, solar or hydroelectricity takes one third of the energy of making electricity with fossil fuels, which waste two thirds of their energy content
- An electric vehicle, regardless of size or type, will use about one third as much energy as a fossil-fuel vehicle
- For low-temperature heat like domestic hot water and space heating, a heat pump needs only one third to one quarter of the energy of heating the same thing with fossil fuels
- For high-temperature heat, induction heating needs only half to three quarters of the energy that would be required using fossil fuels
We can do a rough before and after comparison of what it means to commit to an electrified Australia.
[In work to underpin diagrams in the book] we fastidiously went line by line through the Australian energy data and used the approximate gains in efficiency by electrifying the majority of everything.
Even allowing for growth, and without doing everything perfectly, including some losses in electrical storage and transmission, we can say with some confidence that a commitment to electrification of the Australian economy will more than halve our energy consumption.
Traditional card-carrying greenies bearing battle scars from the energy-efficiency wars of the 1970s, ’80s and ’90s won’t like the one big conclusion you can draw from this. We can have the same cars as we do now, just as big, only electric. We can still have the biggest houses in the world, only electric. We can still have industry and business, only electric. We can have what we have now – using only half the energy.
Of course we should also insulate our homes and seal the cracks and ride bikes and use public transport. All these things would lower our energy requirements a whole lot too. The point is, we don’t have to be perfect to solve climate change. We just need to be electric.
With electrification, more is better
It is important to remember this about electrification: the more, the better. The more vehicles that are electrified, the easier it will be to find a charging station. The more electric cars exist, the easier it will be to use them as batteries on wheels to absorb our abundant renewable energy.
The more homes with electrified heat, the more opportunities for demand response and storage.
The more industries that electrify, the more electricity we’ll produce, and the easier it will become to electrify everything else. More rooftop solar begets more electric vehicles begets more electric heating systems begets more commercial and industrial electrification, more wind turbines and more batteries.
You see the trend here. The more things we electrify, the easier it gets to electrify all the things.
Excerpt published with permission.
The Big Switch by Saul Griffith is Published by Black Inc is available online and in all good bookshops.