Sorry, posting this a bit late. Have been swamped lately with work….
The title of the patent, filed in June 2011, is “On-demand Generation of Electricity from Stored Wind Energy.”
Wind energy? Apple? Don’t be so surprised. Like Google, another technology giant increasingly obsessed with clean energy, Apple operates huge data centres that consume tremendous amounts of electricity, much of it based on coal.
Like most consumer-facing companies, it wants to be perceived as a responsible corporate citizen, meaning it’s eager to tap into low- or zero-emission energy alternatives.
In its patent, Apple describes a way to capture thermal energy resulting from the spinning of wind turbines and then use it to heat up a special fluid with a low boiling point. The heat “stored” in that fluid could then be extracted on demand to generate electricity, similar to how a solar-thermal power plant might operate.
The fact that Apple is looking for a way to “dispatch” wind energy highlights what is arguably wind’s Achilles heel: intermittency. It often blows when it’s required least, and often doesn’t when we have our highest energy demands.
This has left wind energy open to attack by those, for whatever reason, who don’t think wind turbines have a place in our electricity mix. Associated with those attacks is much misunderstanding about how wind energy interacts with our existing electricity system.
For example, the Star received a complaint about last Saturday’s Clean Break column, in which I highlighted the hypocrisy of Health Canada for comprehensively studying the health effects of wind farms but not the oil sands.
In addition to accusing me of being an investor in the wind industry and thus having a conflict of interest – which I’m not, and don’t, unless you include the emotional investment I have in dealing with climate change – the writer of the complaint made the following comment about wind turbines:
“Every one of them is equipped with a gas generator to produce power when the wind fails. Nobody I know in the wind industry has ever stated otherwise.”
This statement is consistent with others which claim that for every megawatt of wind capacity installed another megawatt of natural gas generation is needed as backup.
Because of this alleged dependence on back-up generation from natural gas, another individual asserted in an e-mail that “there is a net-zero environmental benefit” from adding wind energy to our grid.
With regard to the first comment, one can say with absolute confidence that wind turbines are not equipped with backup generators that run on natural gas. This isn’t to say that other energy sources, including natural gas, aren’t relied on as a backup for when the wind doesn’t blow.
“When we’re dealing with the variability of wind, we look at a lot of tools,” said Bruce Campbell, vice-president of resource integration at Ontario’s Independent Electricity System Operator, which manages supply and demand on our grid. “You have to look at this from a system basis. You can’t look at it as one individual technology.”
Often we’ll use electricity generated from natural gas plants to step in when the wind steps out, but it’s not coming from a single point. The grid is like a big tub of water, with a bunch of taps at the top (supply) and a bunch of drains at the bottom (demand).
The goal is to keep the water at the level we demand, meaning there will constantly be a different mix of drains and taps that are opening and closing.
Campbell said Ontario hasn’t yet had to increase its requirement for back-up reserves because of the introduction of wind power. The question to ask is: If the wind generation we have no longer existed, what would be there in its place? The answer is more power plants burning coal and natural gas.
If we were to stick with our coal phase-out strategy without wind, we would need to burn more natural gas. The reality is that when the wind blows it gives us the opportunity to burn less natural gas when it’s being used to displace coal. This is partially why greenhouse-gas emissions associated with electricity generation in Ontario have fallen by two-thirds since 2003.
The dismissers don’t believe it. They contend that fossil fuel plants run less efficiently when backing up wind because of the increased need to start up and cycle. In fact, they claim the inefficiencies are so great that they offset the benefits of wind power.
The efficiency argument contains a tiny kernel of truth, but the impact is negligible according to a detailed study published by the U.S. Department of Energy’s Argonne National Laboratory. It appeared last March in the journal Environmental and Science Technology.
Using the state of Illinois as a case study, researchers found that the inefficient use of coal and natural gas plants and its impact on carbon dioxide emissions is hardly noticed until wind exceeds a 20 per cent share of electricity supply. At 40 per cent of supply, inefficiencies are more visible, but CO2 reductions of 33 per cent are still achieved.
To put this in context, wind was roughly 3 per cent of Ontario’s mix last year and the goal is to achieve 10 per cent penetration through a combination of wind and solar by 2015. We have a long way to go to get to 20 per cent, let alone 40 per cent.
It’s important to point out that the authors of this study didn’t account for the retiring of old, inefficient coal power plants as more wind is introduced to the grid, or the addition of more flexible and efficient natural gas turbines that companies such as General Electric have started selling as a complement to wind.
They also didn’t account for some of the other tools at the disposal of system operators, such as demand-response, dramatically improved wind forecasting, and energy storage, all of which will play a growing roles over the years in Ontario and other jurisdictions.
Who knows, maybe Apple will even make something of its wind-turbine storage patent. Could there be an iWind in our future?
Tyler Hamilton, author of Mad Like Tesla, writes weekly about green energy and clean technologies.