Green Spark Solar Blog

Solar Power

Tidal Power in New Zealand

Tidal power has a lot of things going for it - it is renewable and reliable as a clock but it hasn’t been exploited much in NZ due to uncertainties about the future structure of the power industry here.

In 2011, resource consents were successfully obtained for a tidal power station in Kaipara harbour. This would consist of 200 underwater turbines with enough generation to power 250,000 homes but it got put on hold because of the chaotic effects of privatisation on the power industry and the possibility of a future Labour/Green government centralising (meaning organising) power once more.

There are several forms of tidal power. In Kaipara, the turbines were planned to be 30 metres deep in a channel where the tidal flows are particularly strong. This type of system ( termed Tidal Stream Generation) does not interfere with the action of water and sediment appreciably but there may be some issues with marine life getting caught in the blades of the turbines or avoiding the area due to Electro Magnetic Forces EMF, or underwater noise. The proposal did however pass an assessment by the Environment Court

There are other forms of tidal power that can supply storage that integrates with solar or wind energy with less of an environmental impact. One such is the artificial Tidal Lagoon. This is circular walled structure with a turbine built in a place where it does not interfere with the local ecosystem. Extra seawater can be pumped into the enclosure during times of peak solar or wind production, and the water released on demand as long as the tide is at a generally lower level than the water inside.

At least two other locations in the Cook Straight and also the Chatham Islands already have consents and are just waiting for the right political environment.

December 1st 2016

German Adventures in Solar Power

Germany is the second highest PV installer in the world at 40,490 Megawatts, only surpassed by China. There are approximately 1.4 million solar systems installed across Germany. This is despite the weather, with a large number of overcast days and large seasonal variations in production, particularly in the north of the country.

Much of this success is simply due to government policy. In 2000, the Renewable Energy Sources act was implemented with high tariffs guaranteed at around 60c per kWh. This was in line with the renewable energy target of 60% by 2035.

The cost of these tariffs was distributed across all consumers, but interestingly the cost of grid power actually declined during this period, with savings of up to 40% during peak output times.

As in NZ, the utilities panicked, and instead of adapting to change by supplying centralised energy storage, they put pressure on the government to reduce the tariffs, so that today they are around 12c. The boom period in Germany was during 2010-2013 when around 7 GW per year was installed, representing about 30% of world wide PV installations.

Since that time, solar is still growing but at a much slower rate. It is estimated that about 50% of jobs in the solar industry in Germany were lost. Both brown and black coal are still being burnt and nuclear stations are still running, though the latter are expected to cease in 2022.

Meanwhile solar power keeps declining in price and becoming more efficient. Batteries only have to come down a little bit and there is likely to be another resurgence, even if there is no tariff at all.

November 30th 2016

India’s Ambitious Solar Power Plans.

India was a relatively late player in the current solar revolution, mostly relying on coal and nuclear until 2010.

Since then there has been a literal explosion of solar activity, with 8.63 GW installed as of 2016. That in itself is pretty impressive. Like so much of green technology, the main driver has been economics. India has to import much of its coal and solar energy is simply cheaper. By 2022 the Indian government has projected 100GW of solar capacity. This is more than Germany and China combined.

Most of this solar installation frenzy will be installed to keep pace with the growing population and to deliver electricity to rural areas, about 50% of which have no reliable access to power. The nuclear and coal plants will keep chugging on though because of the high cost of totally replacing them, but the economics will likely catch up with this too.

The domestic solar manufacturing industry is relatively minor compared to China at this stage and is expected to grow significantly with the massive demand. Some of the challenges of installing solar in India is the lack of enough roof space and spare land. Possible solutions are to have the panels floating on special rafts on dams, lakes and canals as this space is free and loss of water from evaporation is another issue. Another possibility is to mount them high above roads, their shading giving greater comfort to drivers and reducing the heating of cities generally.

 India is famous for severe air and noise pollution of all kinds and the effect of solar combined with electric vehicles will be dramatic

November 27th 2016

Tesla Solar Powers an Entire Island.

The island of Tau in American Samoa used to rely on imported diesel fuel to power its generators. There were chronic problems with this set up - including power rationing, shortages, pollution and noise and ongoing expense.

Tau is in a very remote spot but has plentiful sunshine. So Tesla installed 5000+ solar panels combined with 6 Megawatts of Lithium battery storage. This enough reliable energy to power the 600 residents of the island, day and night. It saves 415,000 litres of fuel per year.

Islands are an interesting test case for communities to go fully off grid using renewable energy. Recently a small town in Australia, Tyalgum also voted to go completely off grid using solar, as well as several other Pacific islands.

November 25th 2016

Solar Powered Clothing

Solar cell integration into clothing has a number of uses, firstly charging any electronic gadgets left in pockets, but also storing energy in lightweight batteries to heat the clothing in cold conditions or to power lights attached to the fabric.

The most basic design uses small flexible panels attached to the outer shell. More advanced prototypes actually involve weaving photovoltaic fibres into the fabric along with something more traditional, like wool for example.

A different type of fibre, called Triboelectric nanogenerators can also convert motion into energy and be eastly integrated with the other types, producing a material that is very similar in feel to traditional woven cloth.

November 23rd 2016

E.V’s and electrical charging poised to cause a power crisis.

Electrical Vehicles EV’s are getting increasingly affordable with increasing range. Soon the economics are going to overwhelming move in favour of EV’s, but when the inevitable happens how prepared will we be?

The Tesla Model S P100D gets a range of 500km off one charge, which is a long range well in excess of commuting needs. One of the ways it achieves this range is by having larger batteries - so 100 kWh, hence the 100D. But 100KW is about the same amount of energy that 4 or 5 houses full of people use in one day, it’s a lot more energy than people realise.

If you were going to charge your car up from home using solar cells, in NZ during Winter then you would need a 40KW solar system, that’s not counting other power needs within the home or if you have more than one EV. 40KW is an industrial size, most houses would simply not have the roof space to handle more than 5 KW. You would also need to have triple phase power which most domestic houses do not have, and only about 50% of households ever get approval to convert from single to triple phase

Let’s imagine that the next new car purchase for a lot of people over the next few years is going to be an EV. Then you have trucking and taxis and other forms of transport, all of which can be done with EV’s. This means all that energy that was being supplied by petrol and diesal is suddenly going to be supplied electrically in a short space of time. There is going to be a huge demand for electrical production, maybe 4 or even 10 times current output.

EV’s demand fast charging, especially for longer trips, but fast charging uses a 480V system to deliver a blast of energy that fuels the car in 20 minutes. Now if you have a town with a few dozen or a few thousand vehicles all using fast charging at once, the chances of a brown out or even a black in that town out are pretty certain.

Localised solar power can perhaps take up this shortfall, but we are going to need a lot of it, more than say everyone in NZ covering their houses in solar panels could ever provide. We will need solar farming on an industrial scale using vacant or agricultural land with the sheep wandering around underneath the panels nibbling the grass. Government will not only have to provide incentive but likely produce, finance and install these farms themselves in order to keep up with demand.

For fast charging needs we will need a system of localised power storage that can deliver a blast of energy relatively quickly and cycle many thousands of times. I wrote earlier about flywheels being ideal for this purpose. The panels, the flywheels and the charging stations would be close together to avoid transmission costs.

The speed of this change is going to be amazing to watch, and I don’t think we are ready.

November 21st 2016

Pumped Hydro Storage Possibilities

Pumped hydro is a simple technology that has actively been used since the 1920′s. You pump water from a lower location to a higher reservoir and when you need power you simply release it to flow downhill, the pumping mechanism serving as a generator when run in reverse.

Pumped hydro can release energy at times of peak demand quicker and more effectively that burning coal. It runs at an 80% return of efficiency, less than some other methods but it can store a lot of energy, like enough to power a city for weeks,  and there are no waste products.

Existing dam infrastructure can be used to some limited extent, but only when water levels are low within the dam and there is a surplus of energy being produced somewhere else beyond the dam itself. Otherwise we end up in a chicken and egg energy argument where both the chicken and the egg keep shrinking each time the water goes up and down.

But this is a good combination with solar power, because the peak midday production is normally in excess of immediate requirements and needs to be sold or stored somewhere. If existing dams can’t be used then there is a significant initial investment, but also a number of additional benefits. Pumps and filters fit together nicely, so for example waste water  or even sea water could be pumped and filtered as it goes uphill to form a new reserve of drinking water. Pumps could be used to invigorate depleted lakes and rivers with fresh water, they could even control local climate to some degree through deliberately creating an inland sea or irrigating a desert. And when the water flows out again it generates power.

Abandoned coal mines could be used in areas where the land is totally flat. You have a reservoir at the top of the mine and one deep below and the water circulates between the two. The ski industry already pumps water to high places to give enough pressure to drive artificial snow production. If they used solar cells for the pumping during the summer months when the ski slopes are idle and the solar hours are long, then generate more power to run the chairlifts in winter as well as provide snow cover it is a very good situation.

This is really where large utility companies should be placing their attention right now; by providing mass centralised storage like this and improved water security they keep themselves relevant in a fast changing world; otherwise households around the world are going to be completely off grid very soon.

November 20th 2016

Flywheel Battery Storage

Flywheels work by having a large rotor spinning in a vacuum on magnetic levitational bearings. The rotor is connected by a central shaft to an electrical motor/ generator. The more electrical energy that is fed into the rotor, the faster it spins. It will continue spinning in a near frictionless environment at very high RPM until it comes time to discharge, where it produces electricity via the generator.

To optimise efficiency the flywheel must spin at extremely fast speeds, like 100,000 RPM or 1000 m/s - 3 times the speed of sound. Significant centrifugal forces are developed that can pose a danger if the flywheel were to break or fragment, potentially producing a kinetic explosion. A simple solution is to bury the device underground. If denser material is used then the speed can be lower but of course the centrifugal forces are higher. Therefore tensile strength is most important. Fibre glass resins and polymers give the most strength per weight.

The advantages are very high energy density and durability without the deterioration inherent in electrochemical batteries. Flywheels are very responsive, going from zero to full charge in a few seconds and discharging just as fast if required. They can produce many thousands of cycles without significant wear and tear. There are no nasty chemicals or gases to clean up afterwards.

Hybrid and electrical vehicles  use a regenerative braking principle that is similar to a flywheel, so that when you touch the brake the electrical motor is spun backwards, becoming a generator, which simultaneously slows the car down and charges the battery.

If the battery container could be made robust enough though, then a flywheel could be used instead of Lithium batteries. Other applications could be megawatt sized flywheel farms, with a role to discharge a lot of energy at once, on demand.

November 16th 2016

Moral Struggles Over Car Interconnectivity

The latest generation of electric vehicles are employing a self driving function that talks or senses other vehicles on the road, using wireless, radar and other methods. In an earlier post I mentioned that this interconnectivity could mean the end of most traffic accidents as the car is able to avoid other vehicles ahead of time and in a faster and more accurate way than a human driver ever could. In addition, the vehicle can check the health of the driver and take over automatically if the driver had a heart attack for example.

So imagine that you are in a self driving EV and something unexpected happens like a pedestrian crossing the street around a blind corner. Some calculations take place and the onboard computer determines that a crash is inevitable. Either you hit the pedestrian or you smash into a parked car or you career onto the wrong side of the road and have a head on collision with a truck.

Some kind of judgement takes place over the limitation of damage, who is at fault etc. Perhaps the EV computer talks to the smartphone in the pedestrian’s pocket and determines that they  have a terminal disease. It therefore keeps going straight and runs them over. But perhaps that sick person has a very important function to play beyond the value of  their own life, like they happen to be the ambassador of a foreign country seeking to end a war. So the EV computer swerves into the parked car. But inside the parked car is a pregnant woman so two lives would be lost. So it swerves into the path of the truck. But then it knows that the truck is carrying a load of explosive fuel that could incinerate the whole area causing many deaths.

Then it does a few more calculations and it notices that the pedestrian technically has legal right of way. So it must make a choice whether to break the law and hit the pedestrian anyway. But inbuilt into its code is the strict rule that traffic laws must never be broken under any circumstances, so then it must see if some traffic laws will override other traffic laws and if there are any legal precedents.

At each step of these calculations there is some kind of moral or cultural bias involved. So EV’s produced in different countries may have an AI Artificial Intelligence that reflects where they came from. This means an American EV might run over illegal immigrants without a problem, a Japanese EV might look at what scenario would cause the least loss of face to everyone concerned and send them all an apologetic tweet, ahead of killing its own driver suicidally,  a Chinese EV might work out how to save the most money on car repairs etc.

So then if an accident of this type happened would the blame lie with the traffic laws, the people involved, the software or the culture or morality that produced the software? Pretty sticky.

November 14th 2016

Vanadium Redox Battery for Industry

Vanadium Redox batteries were developed in 1986 in Australia. Their chief advantage is not so much in efficiency but in scalability. One battery system is essentially limitless, because you can increase its storage capacity just by adding more electrolyte, or rather tanks of electrolyte (we are talking about tanks at least the size of a shipping container separated by a thin membrane)..

Gills Onions, an onion processing plant in the USA has 3 x 200 kW modules. Their chief purpose is to store power during off peak periods like the middle of the night and release the energy during high peak times. The other advantage is in covering power spikes, when machinery is first turned on for example, the power spike can be six times the coasting usage and this spike is what the company is billed for - what is termed a demand charge.

This flow battery system is estimated to save the company hundreds of thousands of dollars each year, as well as improving the general stability and reliability of the grid. Vanadium Redox batteries are never likely to be used for electrical vehicle transportation due to size and weight, but for a factory or electrical utility needing a lot of storage muscle the benefits are huge.

November 13th 2016