Public transport and rooftop solar panels. Is there a connection?
Everybody loves public transport ... as an idea. Everybody understands that it is sensible to invest in high quality mass transit that makes efficient use of space and energy rather than having individuals encased in a couple of tonnes of private motor vehicle?
The graphic below is one of a series which makes the resource waste associated with private cars more obvious.
The toll in death and injuries adds another facet to the problem.
But despite the attractiveness of public transport as a safe and efficient mode of moving people, the public isn't always keen to use it. Particularly if they have a car, and if there is parking at their destination and if the weather is nasty and if they must walk a bit before catching whatever form they have available.
In countries where private motor vehicles dominate the transport system there are knock on effects to every sphere of life. It drives urban sprawl; higher greenhouse gas emissions; hospital casualty requirements; more mining; more land devoted to roads and so on.
European countries tend to have old cities with high population densities that aren't a good fit with cars. This is why the UK and France have less than 500 cars per thousand people, compared to Australia with over 700 and the US with over 800. The US State of Montana has over 1,500 vehicles per 1,000 people!
China, on the other hand, has fewer cars not just because of old dense cities, but because her wealthy middle class is still relatively new. So she has just 188 cars per 1,000 people; but its a number on the rise. Nevertheless, her historic low density of cars, coupled with a big population, have made her the fast train capital of the world with over 35,000 kilometers of high speed rail network. In contrast, the US has been trying to build fast trains for decades, but the ubiquity of cars and highways means it's tough to make it profitable; which is the ultimate sin for any project in the US.
Private transport and private energy are strongly analogous. Both are only possible with a certain level of wealth. Both can be essential in remote communities. Both drive expanded natural resource requirements. Both are intrinsically resource hungry. And most importantly, both inhibit the development of efficient solutions to critical problems.
Rooftop panels and batteries are the energy equivalent of private motor vehicles
Electricity demand isn't constant, it goes up and down. The minimum demand is called the base load. It will mostly occur in the early morning when most people are asleep. Some businesses like hospitals and steelworks still operate during this time, as do cold-chains ... refrigeration of various food stuffs, medical supplies and the like.
You don't necessarily need constant sources of electricity to supply this demand, but you need a combination of sources that can deliver that minimum requirement without fail; because when your energy generation is less than the demand, the best that can happen is that some users suffer blackouts; if electricity demand on the grid is 2000 megawatts, but the current production is 1500 megawatts, then somebody has to miss out. It's called "load shedding". Whole suburbs, or perhaps some large industrial users, will be dropped from the system.
A utility scale solar farm and sufficiently large battery or other storage technology can provide 24x7 electricity. The combination of intermittent and storage technologies can make for a baseload system. It's ironic that some people have been keen to call "baseload" a myth, while spruiking batteries as the solution to intermittency. If baseload was a myth then the intermittency of solar and wind power wouldn't be a problem; but it is.
Batteries are expensive. Think about it. If you spend $100 million on a battery, you'll want to use it. To turn a solar farm into a baseload system, you need 12 to 15 hours of battery backup to get you through the night. It's not quite so obvious how much storage you need to make a wind farm into a baseload supply, but it will be considerable. People trying to build renewable+storage baseload systems will want maximum utilisation of their systems to make money. But large numbers of rooftop solar + batteries in homes will slash profits.
With low penetration levels of renewables, making money is easy. But as penetration increases, it gets tougher, particular if you are trying to supply baseload into a system with
high levels of private energy supply.
Battery economics have similar price curves to other products. Buy one megawatt hours worth of AA batteries and you'll pay significantly more than a single battery. If you want to make batteries more expensive, then you build millions of small ones and install them in households, rather than in utility scale farms. This makes for various kinds of inefficiency, the most obvious is packaging and distribution, but one of the biggest will be dealing with householders. This will cost both time and money. The single savings you may make is to reduce the transmission and distribution grids. But you can only make that savings if you succeed in doing away with the grid altogether. Which can't happen while people with rooftop solar plants are getting paid for money they feed into the grid.
What we've done with rooftop solar and batteries is to combine the worst of both worlds. Instead of large durable high quality and efficient energy systems, you get small and expensive consumer-level systems which are not only costly, but reduce the profitability of systems designed for scale and efficiency. Our free market also typically rewards companies who can make cheaper products ... regardless of how long they last. A householder will buy something with a lifespan of 10 years (or even less), but an industry expert will demand durability and will be in a position to demand it and pay for it.
How did we get it so wrong? Plenty of politicians were quick to pass legislation to encourage rooftop solar ... and many took advantage of the early feed-in tariff laws. More than a decade of this has done little or nothing to tackle climate change, but plenty to make real solutions even harder.
Our cities are paying a high price for our love affair with cars, and it's sad to see us making the same mistakes with our energy systems.