Is micro (home) generation of electricity good for the environment?

Home solar
Photo Credit benefit of hindsight

Microgeneration, the generation of electricity by home owners, is becoming increasingly common, especially with the cost of energy going up and the cost of wind turbines and photovoltaic panels for the home falling.

The majority of people deploying these solutions are doing so to 1) lower their home energy bills and 2) to help the environment.

What if I told you that often installing microgeneration equipment does not help the environment?

Bear with me while I try to explain. This is complex, counter-intuitive and I am not the world’s best communicator!

Grid operators have problems integrating renewable energy sources onto the grid right now because they are a variable source of supply. Couple that with the variability of demand and your grid starts to become increasingly unstable.

By far the most economic renewable energy source currently is wind but wind energy’s supply curve is often almost completely out of phase with demand (wind blows stronger at night when there is least demand for energy).

The more renewables that are brought onto the grid, the greater an issue this becomes with grid operators having to shut down production from wind farms in times of oversupply! Bear in mind also that there has to be enough generation capacity from non-wind sources (oil, gas, coal, nuclear, etc.) to pick up the slack on days when the wind doesn’t blow.

In times of oversupply from renewables, it would be far preferable to be ramping up consumption of energy using moveable loads, rather than shutting down production from renewables.

Now consider the home-owner who has deployed their own wind turbine. At times when the wind is blowing this home-owner is generating power thereby reducing their demand just when there is an oversupply on the grid! And if they have a net metering agreement with their utility, they further exacerbate the problem by pumping extra electricity into the grid, just when it isn’t required!

Conversely, on calm days, when extra energy is most needed, micro-generation contributes nothing.

There are two main problems:
1. There are no economic energy storage technologies currently available – though this situation is evolving rapidly with the ramping up of investment into battery research by the transportation industry in particular and
2. Real-time pricing data for electricity generation are not exposed to the consumer – if they were, and automated demand response mechanisms were put in place, you would see a radical shift in the energy consumption curve (people would consume energy when it was cheaper – i.e. when it is abundant).

If these two nuts were cracked i.e. economic energy storage mechanisms were available and real-time pricing data were exposed, micro-generators could generate energy when the wind blows, store it and then profitably sell it back to the grid when demand increases, or the wind drops.

For now though, while microgeneration may be beneficial in reducing your energy bills, it is of no benefit to the environment.

Note that I didn’t address CHP in this post because I was trying to keep things simple! CHP can be beneficial, as can any microgeneration, if the production of energy increases in line with the price of electricity.

As the price of electricity goes up, so too does its carbon footprint. If you consume electricity when it is cheap, you are facilitating the greater penetration of renewables onto the grid. If, as a micro-generator, you can produce clean power when electricity is expensive, then you are helping the environment.

UPDATE: Just to clarify, I fundamentally believe microgeneration is a good thing. However, given the current antiquated state of the grid in many countries, the disconnect between generation and demand profiles for wind particularly, and the lack of decent energy storage technologies, the environmental benefits of microgeneration are far from straightforward. This will change as energy storage options improve and demand response mechanisms and smart grids are deployed.


  1. says

    I’ll bite.

    I think most micro-generation — in Australia at least — is photo-voltaic, not wind turbine based. On the other hand, most larger-scale grid-connected renewable energy generation is wind turbine or land-fill gas.

    So I don’t think the problem of “competition” and “over supply” exists to the extent you suggest.

    While there are issues with micro-generation and it would be great to solve the storage problem, I definitely don’t think its he case that micro-generation is no (zero) benefit to the environment.

  2. says

    You make a good point. Based upon our current energy infrastructure this makes sense.

    In areas where there is no infrastructure, or a depleted infrastructure, like the third world, or communities existing outside of the grid, this is obviously not the case.

    As with all historical shifts, the old paradigm is still established and it’s legacy is still dominant over the new philosophy. This is going to create conflicts until the new paradigm is allowed to become dominant. I would hate to see microgeneration of electricity fall by the wayside.

    Your points do however bring up the case for re thinking how microgeneration links to the national grid, and what we can do with the energy overload. Surely the research and supply of effective energy storing solutions from microgeneration for times when there is no wind or sun should be stepped up.

  3. says

    @Fabian – photo-voltaic microgeneration is very different to wind because it has a generation profile far closer to the demand curve. I was attempting to address this when I said “if, as a micro-generator, you can produce clean power when electricity is expensive, then you are helping the environment.”
    In sunny climes especially photo-voltaic micro-generation is beneficial to the environment.

    @Alasdair – Absolutely, outside the grid, this is not the case, at all. Microgeneration won’t fall to the wayside because it helps people reduce their energy bill so the grid will be forced to adapt to a whole new reality.

  4. says

    I think local storage is the main issue currently. If there were off the shelf storage systems then there wouldn’t be a problem as you would only generate enough energy to keep your local storage full.

    An intelligent and flexible power grid is a must for future adoption. I wonder is any of ESB’s €22 billion being used to look at micro producers? I see they mention smart metering and smart networks so maybe they will.

  5. says

    It’s going to be interesting the difference that more electric cars will make; most people will recharge their cars at night and if they’re producing their own electricity from wind power they’ll be using more of the electricity they produce – not putting it back through the grid.
    I don’t think we can trust our governments to do the right thing when it comes to green power production so I’m loathe to give up on the idea of creating my own electricity…

  6. says

    @John – Visibility of pricing is at least as important as storage. In 2007 the price of generation varied from €0.06 to €1.16 but this variance was never made visible to the consumer. Had it been, they would have reduced consumption dramatically when it was €1.16 thereby lowering the price and lowering CO2 emissions which are very closely linked to price (lower price means higher usage of renewables).
    The ESB are only part of the potential solution in Ireland. Don’t forget CER sets the rules. Eirgrid runs the grid. ESB Networks connects you and ESB Customer Supply manages billing!

    @FairTrade – Electric Cars (EVs) and plug-in hybrids (PHEVs) can make a huge difference to this story. I have written here before on how PHEVs can become a distributed battery bank for energy storage for countries, if the proper vehicle-to-grid technologies are rolled out.

  7. Doug K says

    “2. Real-time pricing data for electricity generation are not exposed to the consumer – if they were, and automated demand response mechanisms were put in place, you would see a radical shift in the energy consumption curve (people would consume energy when it was cheaper – i.e. when it is abundant).”

    I think this is extremely unlikely. Air conditioning puts most of the stress on power supply in summertime, and it’s not needed at night. Similarly I’m not going to cook dinner mid-morning (because I’m at work) or run the dishwasher/laundry at 2am.

    Xcel Energy has a program in CO which allows you to save money by letting them throttle electricity to your house at high-demand periods.
    440 000 customers, out of all the households in the extended Denver area.

  8. says

    @Doug – It depends on what loads you are trying to shift. You are absolutely correct that people are not going to start cooking dinners at 3am when electricity is cheap.

    However there are loads which can be shifted easily. For instance, washing clothes, washing dishes, clothes dryers – if set these to go at 8pm say, and in general, as long as they are completed by 7am, you don’t care when they run.

    Also, thermostats can be ratcheted up or down a degree or two in aircon, water immersions, or fridges without impacting at all on your comfort but over 440,000 households, say, it quickly adds up to a significant load moved.

  9. says

    @Sean – hydrogen production, storage and then burning to create electricity once more is very inefficient – far more efficient is to move peoples’ electricity demand to meet the supply spikes using pricing incentives. This method reduces people’s bills, reduces CO2 production and facilitates increasing the penetration of more renewables on the grid (by smoothing grid instability). Win, win and win!

  10. says

    First off, thanks for the shout out to Morgan Solar, although to be fair, we haven’t really said much yet about our PV panels for the home. (The Sun Simba you linked to requires dual-axis tracking, so we’re not really aiming it at the home market.)

    Second, it’s an interesting point you’re making, but I’m going to raise a few points (in no particular order):

    – Demand is steadily increasing and the price of electricity is expected to at least double in the next five to seven years. So, even if everything you said was true, how long will it remain true?
    – There are very few places where home micro-generation is all based on wind (or only one clean energy source). There seems to be a balance between wind, solar, geothermal, biomass and solar hot water. Where there’s a mono-culture of home micro-generation, it tends to be solar…. right?
    – Solar power output curves follow peak demand curves, with solar falling off a little faster than demand in the evenings.
    – Wind and solar tend to be complimentary; most windy locations are windiest during the evenings and at night.
    – Demand is traditionally highest on peak solar power output days. (Hot and sunny = high demand and high solar output.)

    None of these points invalidates your argument, but you don’t seem to take any of them into account.

    Reading through your post again, to paraphrase you: People with wind generation don’t necessarily help the environment, because their wind turbines are most productive when the grid is over supplied with wind energy. (Yes?)

    I would really need to see evidence for that before I took that claim at face value. Assuming that’s true (it could well be), and ignoring all the points I raised that complicate things, you’re still overlooking the fact that every grid has to be managed, both in terms of meeting demand AND load balancing.

    Most grids are subject to local spots of higher demand, lower supply or lower voltage, so even a grid that can technically meet demand can be subject to local areas of under-supply. This load balancing is VERY tricky, and the best way to deal with it is often to lower local demand either by conservation or micro-generation.

    They way they resolve this now on most managed grid is to keep additional dispatchable power supplies in reserve. These have to be distributed so they can serve demand or load balancing purposes. Most grids maintain at least some power stations, usually natural gas or coal, which are kept in reserve for both peak demand and load balancing purposes. Natural gas plants are popular as they can fire up quickly, cost less to have sitting idle and are relatively clean and inexpensive to build and run (as long as you ignore the CO2).

    The more often the grid is oversupplied, regardless of the reason, the less often these additional plants are fired up, especially if the over-supply is coming from distributed local generation.

    So a more frequently over-supplied grid can easily mean a grid with a lower overall carbon foot print, if that over supply is a result of additional supply from clean sources or lower grid demands (requiring less load balancing) resulting from home micro-generation. In either case, you have a circumstance where the normal (carbon emitting) reserves are running less often, which benefits the environment.

    So maybe it’s safe to say that the benefits of wind are more indirect than most people would assume.

    I’ll admit, I may have missed something fundamental, and I’ll also admit the only grid I know even remotely well is Ontario’s. I know just enough about California’s and New York’s to know that most of what I said applies there too. (I’ll also admit that I’ve really been burning the candle at both ends this week, so for all I know this whole reply has been nothing more than long winded, incoherent non-sense.)

    Still, interesting post, it definitely made me think, and I definitely agree with every word in your update at the end.


  11. says

    Just one small point about microgeneration; I want to do it to be as independent as I can be. I read of the daily rolling blackouts in my home country of South Africa because the government had inadequate power plans. I read of millions of homes in Southern States without electricity because of a couple key failure points. I see Ireland with very little of its own power generation. If peak-oil, Russian gas bullying tactics and the financial crisis deepen I wonder how Ireland would be able to cope if panic ensues and supplies are cut.

    It isn’t all doom and gloom. I hope by starting now that when the storage and metering problems are solved I will be ready to contribute. Then hopefully the environmental payoff will happen too.

    And as for 2am washing cycles, doing it a lot lately with a newborn in the house 🙂

  12. says

    Nic Morgan’s comments on solar PV are absolutely correct. Because Solar tracks daily peak demand (especially in climates with a lot of air conditioning) then it is a great source of power and does displace carbon. However, I see no contradiction with Tom’s point. Tom’s case is very applicable to Ireland where we want to get to 33% renewables (wind in our case) for electricity generation by 2020. The output of a wind turbine varies with weather and average output of a wind turnine is 30% of its rated capacity. Therefore, in order to meet the 33% target the installed rated capacity of Ireland’s wind farms will exceed the average demand and will exceed to summer night demand by approximately 150% if we don’t change our load profile. Obviously therefore we will at some times have too much wind energy.

    It seems to me that the key point is not that you generate green energy but that you consume green energy. If you modify your consumption pattern to match green energy supply then you maximise the market for green energy. This only becomes an issue when renewables reach a significant proportion of the grid. It seems to me that Tom is pointing out a problem that is going to be a big issue rather than one that is a big issue.

    Paul Watson may have to wait a long time for electricity storage to become cost effective. At the domestic level, it seems to me, it is better to think in terms of energy rather than electricity storage. A hot water tank or a EV battery is more cost effective than a dedicated device to store surplus energy as it has a primary function of value and performs a storage function as a free byproduct.

    Using electricity at times when it is more abundant (aka cheap) instead of when it is scarce (aka expensive) is a remarkably green activity. As time progresses real time markets for electricity will become the norm to encourage people to move load to cheap (aka efficient and/or renewable) production times.

  13. says

    Bravo to you too Nic, I’ve learned a lot from this thread. I’ve never thought about this in depth, and always only thought of it in terms of off-grid completely. I’ve a new perspective on it all now.

  14. says

    Hello, I work for and this is what I do for a living, help homeowners build and install wind/solar hybrid systems. If you are not deploying a balanced wind/solar system, and putting in no batteries, the points are well taken. Our best selling system is the smaller rooftop mounted turbines that connect with a solar panel to give clean reliable power. You see, since the wind is stronger in the winter months, sun is stronger in the summer months, that gives an even flow of energy year round. Additionally it counters some of your points about night/day. The kits we install, most do not tie to the grid, they are stand alone off-grid systems that power (some) appliances in the home. This way, we can calculate with an energy meter, the usage of appliances, decide which ones a system can support, and take (some) appliances off-grid. This is far cheaper than expensive grid-tie systems and more scaleable. For me, it was two refrigerators and my exterior 3 car garage workshop, off-grid, powered by two rooftop turbines, two solar panels, and a few batteries. Cheap, scaleable, effective, and subject to none of the issues in the article. Small DIY Wind Turbine Kits

  15. robin says

    Storage can be cheap if your on a hill
    2 water tanks.
    pump up to the top tank during the day; then you have on demand supply for the night.
    stores forever with zero loss