The Grid is Good: Tesla, Batteries and Where They Fit in Clean Energy
It’s hard to miss the news that Tesla is about to reveal plans to roll out lithium ion batteries capable of powering a home or a business. The news is cool. It has that Tesla edge, and is getting a lot of attention even though battery technology at this level isn’t new in and of itself. Other companies have explored potential battery products, though they haven’t gained much traction. I’m really interested to see what Tesla brings to the table. High-performing batteries could really push us forward in the movement to transition to clean energy.
When it comes to electrical-based energy storage devices, the game is about power density and rate of charge/discharge. There are two players in the game: super capacitors and batteries. Super capacitors can charge and discharge quickly but have a low energy density. Batteries have a much higher energy density but are slow to charge and discharge. All of the research right now is on increasing energy densities (using anything from graphene to egg shells and chicken bones) and increasing charge/discharge rates with a goal of ending up with an uber-battery! We’ll see if Tesla has made some incredible advances.
Tesla’s brand-name news has inspired conversations about how lithium ion batteries can dovetail right into existing photovoltaic (PV) systems to significantly reduce dependence on the power grid. I’ve also heard talk from people who are excited about the prospect of going off the grid. But I’d strongly advise against doing so, especially for institutions or business owners.
The grid is actually good. It’s a network for energy transmission, just as the internet is a network for data transmission. It helps us to optimize when and how and where power is used, and used effectively. As such, it's not the biggest challenge in being more sustainable with energy. Instead the big challenge is our choices in power sources and their locations (usually far from where the energy's actually used). Ideally, our energy would come from distributed, clean (solar, wind, etc.) sources located near usage (such as an on-site PV array at your home or business), but networked to balance and share production and use. We want that clean energy to be a part of our overall energy management plan. That's one big reason why "going off the grid" is counterproductive. Here are others:
- Introducing batteries decreases the efficiency of a PV system by roughly 10%. All of a sudden your self-produced energy isn’t working as hard.
- Going off grid requires you to design your PV system to provide enough energy for the worst sunlit months. This means either PV system needs to get larger (usually by a factor of 5-10!) which, will create unused, wasted kilowatt hours (KWh) in the summer, or you need to increase your battery size to store energy from the summer for the winter. Kind of like canning your summer vegetables.
- If you’re connected to the grid, then excess energy can flow back onto it for use elsewhere instead of being wasted. And you can also earn utility credits for the energy that your PV system gives back to the grid. In effect you are greening the grid.
If anything, clean, sustainable sources such as PV arrays should absolutely be connected to the grid. And lithium ion batteries (Tesla’s or otherwise) have potential to shine as a part of that grid for:
- Load-shifting: Moving load from peak demand to low demand, and decreasing energy bills.
- Grid stabilization: The stored energy can be accessed quickly to counteract blackout-causing transients on the grid.
- Balancing wind power and solar power: storing un-needed energy from wind and solar power and using it when it is needed (canning those kilowatts!).
- Emergency power sources: lithium ion batteries have a much greater power density than existing lead-acid battery systems, saving space.
If you’re still excited about going off the grid (whether for ideological reasons, or perhaps you’re building in a really remote area where trying to connect to the nearest grid isn’t cost effective or even plain impossible), then I’d advise some careful planning. There’s definitely more to it than just attaching batteries to your power source. Work with a specialist who can really help you to assess your needs, and who can help design a system that will meet those needs as effectively and efficiently as possible.
The opportunities for really smart energy production, distribution and usage are getting better and more cost effective every day. It will be exciting to see how Tesla’s work in this area (as well as that of other fellow innovators) is about to push us ahead even farther.