It's time for a smarter grid
Imagine for a moment that you are the head of a large group of network operators, faced with a decision about what to do about rising peak electricity demand. And you are presented with a choice: invest $2.6 billion over five years on upgrading your network – the route you would normally take; or spend a comparable amount on solar power and energy storage, distributed throughout the network.
This was the question posed by Professor John Bell, of the Queensland University of Technology, and Warwick Johnston, a leading solar analyst with Sunwiz, when they sought to find out if there was a better way than the traditional response of building more poles and wires to cope with rising peak demand.
Using Queensland network operator Energex as an example, and its forecast peak demand growth of 1.25GW over the five years to 2014/15, the study analysed the existing approach of spending $2.6 billion augmenting the grid, or investing a comparable amount in either 25GWh of storage, or 1.25GW of solar PV and 10GWh of storage.
The study concluded that a combination of battery and solar PV produced a far better outcome, because of the ability to generate revenue from the energy produced, and the use of battery storage to resell energy. Over a five year period, the net present value (NPV) of the poles and wires solution was negative $2 billion, while the NPV of the solar/storage solution was negative $750 million. But because these could produce revenue over a 20-year period, the solar/storage had a positive NPV of $2 billion over a 20 year period.
Bell and Johnston say the main take-home messages from this are that the integration of distributed PV and battery storage into the existing energy system has the potential to be cost effective now, and it underpins the case for reform of the National Electricity Market, to ensure that distributed generation is fairly treated and that network providers are encouraged to opt for the solutions that have greater market benefit, rather than simply being least upfront cost.
Interestingly, this is a theme picked up by the Australian Energy Market Operator in the latest update of its National Transmission Network Development Plan (NTNDP) that has been released on Wednesday. The AEMO has been pushing its NEMLink proposal, which is designed to reinforce the backbone of the National Electricity Market, and transform it into a truly national market (except WA) rather than a series of interconnected regional markets.
However, under the strict guidelines of the current regulatory framework, AEMO says that it cannot justify the investment, even though its studies conclude that on a broader economic perspective (such as the increased build out of renewables and other generation, avoided losses etc), it would deliver a net benefit of $3.5 billion.
“Traditionally, transmission augmentation occurs around known load and generation centres, but we are now seeing new generation based in more remote areas, and the nature of load profiles is changing along with the nature of the market," it writes. “We need to take a new approach to future investments in transmission to maximise the benefits of this new generation.”
The AEMO report looks specifically at how to meet the expected build out of wind generation over the next decade, and potentially geothermal and solar thermal in the decade after, and how to best plan for the deployment of gas as a significant transitional fuel source (it notes it might be cheaper to build gas pipelines rather than transmission lines in some cases). And it also looks at how to manage the inevitable growth of rooftop solar PV, and the anticipated boom in interest in electric vehicles.
While the AEMO takes a more conservative approach that Bell and Johnston, the report has recognised the potential of new technologies such as solar PV and EVs to alter demand and network spending patterns. On PV, the report said it has the potential to moderate peak demand; and it’s not just the number of electrons that are produced by the panels and at what time (subject to considerable debate among readers of this web site), it is because the owners of solar PV and other “own-use” generation are showing significant changes to their own consumption patterns.
The study found that the scale of small-scale solar over the next 20 years would result in a significant contribution to energy produced, particularly on clear days, and the combination of rooftop solar PV and owners matching their consumption with their output would also help reduce maximum demand, to the point where network investment could be delayed, especially in those areas with high PV uptake. However, it did not look at storage, a key component of the Bell/Johnston analysis.
The study also looked at a scenario where there was a high level of EV uptake in a city such as Sydney to learn the potential impact on the grid, particularly at peak times. In winter, because the peak is later, when people would presumably plug in their cars and their heaters at the same time when they got home, the impact was more dramatic. But in both cases, where 50 per cent of the EVs had controlled charging schemes – plugging in at 11pm or 2am – the impact was much reduced.
The findings underscored the need to have incentives to encourage customers to charge the cars at certain times, to impose standards for charging points to do the same, and the ability for remote control of charging points. And the report also recognised the potential to use plug-in vehicles as a source of power during those demand peaks and actually reduce network loading at peak times. This technology (sometimes referred to as vehicle-to-grid) is still in the early stages of development, the report finds, but it has the potential to provide more dynamic demand and supply characteristics.
Comments on this article
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Battery life
The life span of the batteries is very dependant on the quality and depth of discharge. Always look at the exponential cycling curve of a battery type as you can match the DOD to the life cyles of the batteries.
Stand alone power systems have a large capital cost but when you compare them to diesel consumption and the maintenance cost of generators, solar stands out.
I say to people who are looking to the future there are grid connect systems that can be easily converted to off grid systems, Pay the extra price for the equipment and think of sustainabilty and non-reliance of networks.
"it's the efficiency stupid!"
I do not agree with the idea of a DC powered house. We have uninteruptible power here from a 48V battery bank charged by a hybrid inverter (no longer in manufacture) which also feeds the excess to the grid. The storage capacity is 500Ah, and we could, if we needed/wanted to, run the whole house (yes, even the toaster!) all night long indefinitely and still feed excess to the grid....
As we hit the wall of Limits to Growth (Australia will be totally out of oil by 2020 - http://damnthematrix.wordpress.com/2011/07/31/how-australia-will-run-out...) EVERYONE will have to tighten their belts. They will because the cost of power will rise dramatically - I think everyone should pay the same as the Feed in Tariff we get, 52c/kWh. Because when you pay too little for power, you simply don't value it.....
I also hasten to add, we have had untold and expensive problems with batteries. After seven years, we're on our fourth battery bank. The first was way too small, the second used and the third Chinese crap that barely lasted long enough to run out of warranty. Our current bank is ex-Telstra and should hopefully last us a very long time. http://damnthematrix.wordpress.com/2010/10/04/powering-up-for-the-collapse/
The main problem with batteries is that there are not enough resources left for everyone to do as we did. Lead is already in short supply (or maybe I should say demand is way too high), and Lithium only comes from one viable source in Colombia. We should reduce consumption by 80%. It can be done.
Here's to the crazy ones
Bravo I say to any Network Operator CEO who puts Professor John Bell's proposal into practice.
Australia needs a CEO willing to put their career and $2.6 billion of shareholder funds on the line.
We need a CEO with courage if we are to make any progress here.
Avoidable inefficiencies
What about connecting solar PV batteries, and connecting the batteries to the inverter?
To decrease inversion losses, also connected to the batteries would be the house's lighting circuits (LEDs), and rechargers for all domestic battery-powered devices, (including the mower and the EV?)
Inefficiencies
Batteries will clearly represent losses during charging and discharging. A quick google didn't reveal much in the scale of inefficiency while charging and discharging, but Spectator attracts some very technical folk and we may yet enlighten ourselves. I see the study as measuring the merits of increasing distributed systems at the expense of central systems, rather than increasing central systems. The charging losses of batteries and of converting DC to AC and back, etc, have to be weighed up against losses of transmission. Transmission losses would i'm sure be a factor of distances and demand over capacity, as overloaded systems invariably heat up and get in their own way with heat resistance. Also central systems have to transmit to different areas, different distances away and different loading patterns, meaning the range between high and low loads is likely to be greater than in distributed systems. And the generators don't get the constant and instant feedback they need to adjust. Assuming the generators are guessing demand, energy security is important and generation is on the high side this creates losses. If the report has weighed these up then it would have high contribution value for system design.
Batterys: Getting charged up about nothing
Don't forget there are inefficiencies in batteries.Plus all the charge control gear and the limter equipment that would be required to minimise peak load on the system. Cap X costs are also not attractive. More efficiency and smarter demand management is required rather than consuming more eco-products in a battery powered lifestyle.The battery solution proposed could have a larger CO2e footprint!!
Also DC wiring in the home is expensive, especially at the lower voltages where extra heavy cable is required to make up for voltage drop. I have previously wired a house for 240V power/ 12V (24,48) lights, this set up is typical in small RAP systems and some adventorous grid connect home owners. Separation of different voltage ranges is typically practiced in most commercial and industrial jobs, so wouldn't take much to adapt to housing.
Personally I am up for smart grids and smart load management, batteries may or may not play a part in that reality
Smart people with smart meters provide smart solutions!
Only people with heavy investment in power line construction companies and people regarding massive power poles as beautiful would oppose a smart solution. Ceramic Fuel Cells, Solar PV , Wind Power and Smart Meters combined can eliminate the need for massive investments in new large power lines. Does it really matter if a smart meter stops me from us a washing machine during peak demand times? I am sure the sky will not fall down if during peak demand electric hot water systems are off-line. If we use our brain and let ourselves being helped by smart meters, then we can have most of the convenience of electricity at an affordable cost with less harmful impact on our environments.
EV charging and power requirements
Was it here that a recent discussion concluded that EVs are not likely a serious power consumer?
Most cars don't get driven very far each day, trips to local shops or a 30km work commute.
Using an example of a 50km per day electric vehicle and assuming efficient energy consumption of about 16kwh per 100 km (Mitsubishi iMiev), the average EV will need about 8kwh per day.
Most households consume about 15-20+ kwh per day, so the addition of an EV won't dominate the electricity consumption in these households.
I have several associates that have built their own EVs and are currently running their houses and cars from solar PV power while exporting nett energy to the grid. about 4 or 5 kw of PV power is needed to make this work.
Add domestic-and-EV some battery storage to this mix and it will be possible to effectively eliminate the electricity grid. About 20 or 30 kwh of battery is needed, conveniently, this is about the same size as a EV battery, of course, the EV has to be plugged in. Retired EV batterries would work well in the domestic role.
Bi-directional battery chargers (part of V2G technology) would allow the EV and any domestic storage capacity to become available to elecricity suppliers.
In Western Australia this is never going to happen! As mentioned in my previous post, fake privatisation and stifling monopolies will not allow small scale generators to access dynamic market prices. They (Synergy and Verve) must be killed and replaced with responsive enterprises.
My batteries are AC
There is a good reason for this.
Low voltage (12/24V) is OK for low power applicances, such as LED lights, but the currents become too great when any power is needed, as is the case for a washing machines, toasters, microwave ovens etc.
The volrage drop and cable size requirements make these high power applicances (with built in water heaters) untenable on low voltage. The high currents increase the risk of terminal fires.
The larger 240VAC sinewave inverters are efficient. The unit that I use (huge troidal step-up transformer) uses about 25 watts to keep it energised (think of this as 1/2 of a 200 watt PV panel) so that the clocks and small lamps work. It's better than 90% efficient when driving the toaster.
I do completely agree that most domestic lighting could easily be implemented on 12 or 24 volts. One potenetial issue is keeping this separated from 240V circuits in the roof space.
Batteries are DC = Efficiency gains for home uses
Batteries can be charged directly from your PV. This potentially means that DC appliances around the home don't suffer energy losses from converting to AC, and then back to DC for LED lights, notebook computer, or whatever you are running. I say potentially because the market for DC appliances has not been well developed, and this system would duplicate AC wiring through the house. Still, sparkies should do the feasibility study on DC wiring houses. Depending on current draw, surely 12/24 volt wouldn't have the same safety standards and fault breakers required by 240 v.
http://www.theengineer.co.uk/sectors/energy-and-environment/news/direct-current-electricity-could-cut-power-bills-claims-creator/1010577.article
is this study in the public domain?
If so, a link would be great. If not, that's a shame, as it sounds like an interesting report.
NBN battery and solar PV
we will need a battery for the NBN telephones at home - so will one battery satisfy both needs ? - food for thought !
Markets will assist
Car charging incentives would of course involve smart meters and a retail energy rebate for switching on at 11pm. With battery storage at home in addition to this, i think the constant energy supply to each home (that is, the 24/7/52 level of energy supply to all homes, all of whom have an EV) would be of the order of 1.5 - 2 kW. Home storage would be a significant upfront cost which could be assisted by network operator investment, but the question remains could all planned reticulation system augmentation be then cancelled because of peak load removal. (????)