Electrical power in New Zealand is generated majorly from renewable energy sources such as wind, geothermal and hydropower. Renewable energy sources contribute 75% of the total power generated in the country. As a result, New Zealand has one of the greenest energy infrastructures in the world. Energy demand in the country has been steadily rising by an annual margin of 2.1% from 1974 to 2010. However, energy demand fell by a margin of 1.2% in the period spanning from 2010 to 2013. New Zealand is above average in global energy intensity ratings. However, it has also been ranked among the worst performers with regard to energy efficiency. As a result, energy generation in the country is not aligned to the demand, which forces the government to import energy. Transpower New Zealand Limited (TPNZ) is an electricity utility company owned by the state and is responsible for power distribution in the country. Transpower plays two roles in the energy market in New Zealand. Firstly, the company owns the national grid that connects the consumers to the power stations. Also, it enables competition in the energy market thereby eliminating monopolization of the energy business to the benefit of the consumers (Electrical Engineering Portal, 2013). This paper explores the need for expansion of the national grid in New Zealand and the accompanying implications such as cost, fair distribution of power, regional power demand, and health issues caused by transmission lines among other.
Energy demand in New Zealand
For Transpower to effectively carry out a grid expansion, it must identify the existing demand and match the grid coverage with regional demand patterns. Failure to do so would lead to economic losses as the infrastructure would be put up but without matching demand, it would remain unused. This paper will explore the electrical demand pattern in New Zealand in a bid to assess the need and feasibility of a national grid expansion project.
New Zealand has various types of electrical power consumers who range from industrial plants such as the NZAS aluminium smelter, commercial buildings, and residential households. The national annual electricity demand averages at 40,000 gigawatt-hours and almost two thirds of this power is used in the North Island. The electricity demand in the country follows a certain given pattern. For example, during the hot and dry season, consumption is low due to the reduced space heating loads in buildings. This enables power generators to conserve hydro storage by reducing the number of active hydro generators. Conversely, maximum demand occurs during winter that runs from June to August (Transpower, 2016). The graph in figure 1 below depicts the national demand curve for the years 2014, 2015, and 2016. The graph shows that demand in the early months of 2016 has been the same with that of 2015 over the same duration but 2% higher than that of 2014.
Figure 1: New Zealand national demand curve for the years 2014, 2015, and 2016. Source: Transpower, 2016.
Power demand in North Island
In New Zealand, power demand patterns can be studied from a regional perspective as different regions exhibit different levels of demand. North Island has a higher power demand as compared to Southern Island. Therefore, any expansion of the power distribution network should give special focus to the Northern region. Figure 2 below depicts the power consumption pattern in the North Island region. From the graph, it can be seen that demand in the early months of 2016 has been the same as that of 2015 during the same period but higher by 1% over that of 2014 (Transpower, 2016).
Figure 2: Power demand in North Island during 2014, 2015, and 2016. Source: Transpower, 2016.
Power demand in the South Island
Power demand in the South Island follows the same pattern as that of North Island whereby the demand in early 2016 coincides with that of early 2015 and is above that of 2014 with a margin of 3% (Transpower, 2016). Figure 3 below shows the demand pattern in South Island.
Figure 3: Power demand in South Island. Source: Transpower, 2016.
Consumption patterns
The major energy consumers in New Zealand are industrial plants and domestic households. Electricity demand follows a certain pattern that changes from time to time and hence supply must be adjusted to meet the fluctuating demand. Demand is lowest during winter and highest during summer. However, demand during summer has been steadily increasing due to use of electrical equipment such as air conditioning system and irrigation pumps (Electrical Engineering portal, 2013). Figure 4 below shows the typical demand profile of a residential house. Residential dwellings take up about 30% of the total consumption with the major loads being space heating, water heating, and lighting systems.
Figure 4: The demand profile of a residential house. Source: Electrical Engineering portal, 2013.
An overview of the transmission infrastructure in New Zealand
The national grid in New Zealand comprises of high voltage transmission lines that measure up to12000 Km. Majority of the power transmitted is in the form of an alternating current (HVAC) but there is a high voltage direct current (HVDC) that runs between Haywards and Benmore. The HVDC transmission system consists of a set of cables running under Cook Straight which is known as the Cook Strait cable. Due to the geographical shape of New Zealand, the power transmission network comprises of a long trunk-like system running from North Island to South Island with smaller branches jutting from it along its length. As such, electricity supply in many locations in the country has only one path to flow from the generator to the consumer. As a result, if there is a fault in a given transmission line, the area that it serves remains without power until the problem is rectified (Electrical Engineering Portal, 2013). This is a departure from advanced electric transmission systems that have alternative distribution lines for delivering power to the final consumers, such as the ring system.
Also, the geography of New Zealand makes the use of long transmission lines necessary due to the long distances between power stations and consumption centers. Such is the case for the hydro power plants in south Island. As a result of the long transmission lines, high power losses occur which can be up to 3% but can also go as high as 7% (Electrical Engineering Portal, 2013). The losses are occasioned by the resistance of the transmission cables which converts electrical energy to heat. New Zealand is an island nation. Therefore, it cannot import or export power to other nations like other inland nations. As a result, the country has to be self-sufficient and meet all its energy needs. New Zealand can only import energy in form of fuels such as coal, diesel, and petrol.
Figure 5: Schematic representation of the power infrastructure in New Zealand. Source: Electrical Engineering Portal, 2013.
Once the power is delivered to a demand zone, it’s fed to a distribution network. The distribution network is classified into two categories, the local and secondary network. The local networks are connected to the national via substations, which are used to step down the voltage from the transmission voltage to the distribution voltage. Secondary networks are used within a confined zone, such as within a residential estate or an industrial plant (Electrical Engineering Portal, 2013).
Figure 6: An illustrated diagram of power transmission systems in New Zealand. Source: Electrical Engineering Portal, 2013.
Sources of energy in New Zealand and their effects on the transmission grid
Most of the energy generated in New Zealand is obtained from renewable energy sources. The renewable sources include geothermal, wind, biogas, and hydro power. In 2014, the total renewable energy in the country’s energy mix stood at 79.9%, an increase from that of 2013 which stood at 75.1%. The amount of renewable energy generation in the country has increased steadily since 2009. The percentage increase in 2014 stood at 7.1% as compared to 2013 due to increase in renewables such as geothermal, wind and hydro projects that were brought online (Chadha, 2015). However, generation from biogas and wood projects saw a marginal decline. Geothermal energy registered the biggest increase in the energy mix with a total of With 6,847 GWh being generated from geothermal plants in 2014 thereby overtaking natural gas generation in the country for the first time in decades. Wind on the other hand generated a total of 2,187 gigawatt hours in 2014, an increase of 9.4% from the quantity generated previously in 2013. Wind energy surpassed coal in the same year and became the fourth largest power source in the country. On the other hand, power generation from fossil fuels fell by a margin of 18.4 between 2013 and 2014. Also, generation from coal and natural gas dropped by 18% within the same period. New Zealand has a target of reducing fossils energy generation to 10% of the total energy by 2025 (Chadha, 2015). Figure 6 below shows a chart of amounts of energy generated from various sources.
Figure 7: Chart of electricity generation from various sources in New Zealand. Source: Clean Technica, 2015.
The need for expansion and optimization of the national grid
The intermittent nature of renewable energy leads to negative effects on the transmission grid such as voltage variation and voltage flicker and frequency fluctuation. Other effects of renewable energy on energy systems include power harmonics, small time and seasonal of long time power fluctuations, islanding, and protection issues. Since it’s expected that the amount of renewable energy in the energy mix will only increase, hence these effects associated with renewable resources shall only increase. The grid can be optimized for renewable energy integration through such methods such as the use energy storage systems to reduce voltage fluctuation. Also, the intermittent nature of renewable energy sources can be mitigated through the use of power electronics such as fast semiconductor switches that can adjust the power system in line with the power fluctuations (Sandhu & Thakur, 2014). In addition, the grid can be optimized for renewable energy integration through complex computer algorithms that can run real time digital grid controllers to make the grid more responsive to power changes.
Also, from figure 5, it can be seen that the transmission lines run along the length of the country and little efforts have been done to ensure effective reach of the power to the edges of the island. As such, towns along the country’s edge, such as Ohura, and the country’s smaller islands, such as the Great Barrier Island have no power at all (Radio New Zealand, 2016). As such, these residents of such towns and islands are used to use inefficient and unreliable offgrid systems such as solar photovoltaic power systems. Therefore, there is an urgent need to extend the grid reach to such places as development has been derailed due to the lack of power. Also, the residents of such towns and islands experience a diminished quality of life due to lack of amenities such as hospitals, space heating and air conditioning, and communication devices such as the radio and television. The government of New Zealand should consider these people and the hard life that they endure living without power and extend the grid reach to their localities. Also, the government is supposed to treat all the citizens equally, even the people living in remote locations and hence power should be availed to all parts of the country, which creates the need for extensive grid extension.
Also, other peripheral factors create the need for grid expansion. For example, the majority of the grid infrastructure was constructed in the 1950s and 60s and therefore it has been unable to cope with the increasing load capacity. The growth in power demand has been higher than was predicted four decades ago (Transpower, n.d.). Also, the grid is ageing and needs to be upgraded in line with technological and economic advancements.
The cost of electricity grid extension in New Zealand
Transpower is a state owned company that was formed in 1994. The company is charged with the mandate of running, managing, maintaining, and building the national grid in the country. The company takes power from the generators and delivers it to the final consumer. Some of the most prominent energy generators in New Zealand include Meridian Energy, Contact Energy, Mighty River Power, Trust Power, and Genesis Energy. Transpower operation costs are charged to the energy consumer and only take up about 10% of the power bill (Transpower, n.d.). However these charges vary depending on how the line companies distribute costs to their consumers.
Transpower has a business model that can enable it to foot the cost of constructing additional transmission lines. The company is a state owned enterprise and is therefore required to earn profits from its investments. As a result, Transpower have a large pool of resources saved up for emergency operation such as grid restoration, repairs, renovations, and expansion. Therefore, Transpower can fund the grid expansion projects from its own balance sheet or it can alternatively secure debt funding (Transpower, n.d.). As such, no additional funds would be required to be injected into the project by the shareholder, which is the government.
The Electricity Authority determines the pricing mechanism to be used in the energy market in New Zealand. The pricing mechanism is defined in Schedule 12.4 of part 12 in the Electricity Industry Participation Code 2010 (Transpower, n.d.). The pricing methodology enables Transpower to recover its investments in grid construction projects by increasing its percentage compensation per every unit of power flowing through the grid.
Health issues associated with high voltage electric transmission lines
High voltage current currents flowing through a transmission line produce two types of fields, electric fields and magnetic fields. These fields are the resulting components of the electromagnetic fields. The magnetic field is the most dangerous among the two due to its ability to penetrate the human body. This field is potent within a distance of 300 meters from the transmission line but its effects fade away as the distance increases. Other factors that influence the effects of the magnetic fields include the configuration of the transmission lines relative to each other and the current and the voltage flowing in the lines (Parmar, 2012). The electromagnetic fields (EMF) created by the voltage in the transmission lines is strongest under the power lines.
The human body is made up of live tissues such as bones, blood, muscles, and skin. The permeability of the human body to electromagnetic fields is equal to the permeability of air but the different body organs have different permeability levels. The human body contains electric charges that flow in ion rich body fluids such as the lymph tissue and the blood. When EMF generated by the transmission lines enters the human body, it alters the flow of these charges through the process of magnetic and electric induction (Parmar, 2012). As a result, the charges cannot perform their destined functions in the human body leading to health issues.
The EMF impacts on the human body by attracting and repelling the free charges. As a result, the charges are moved to either side of the human body depending on their polarity and the orientation of the electromagnetic field. The knowledge on the effects of EMF on the human health has existed for the last few decades. Living close to power transmission lines for prolonged duration of time has been shown to cause the health issues such as various types of cancers and leukemia. The correlation between EMFs and health problems in humans was first brought to light in the American Journal of Epidemiology by Wertheimer and Leeper. Since then, several studies have been done on the subject and it has been proven that EMFs can cause health problems such as brain cancer and blood diseases. Other EMF releated illneses include alzheimer’s, heart diseases, hormonal imbalance, fatigue, depression, Lou Gehrig’s disease (ALS), and breast cancer among others (EM Watch, 2016). Therefore, due to the potential harm that the transmission line poses to human health, Transpower should ensure that the grid expansion project transmission lines do not pass near residential areas.
Conclusion
The Transpower Company in New Zealand should undertake a grid expansion project. The current grid being used in the country was designed in the 1950s and 60s and as such, it is not fit to support a modern economy. The power demand load has also increased than the figures projected 40 years ago. The country uses an inefficient grid design with only one rout for power to reach the consumers. Also, regions along the edges of the islands are not served by the grid and hence experience a poor quality of life. Transpower earns profit from the charges levied on power shipped through its grid network. Therefore, it has enough resources to fund a grid expansion project or guarantee a development loan. Its Transpower’s responsibility to serve all the country’s residents with power and hence it should extend it grid to reach all parts of the country.
References
Chadha, M. (2015, March 31). Wind Replaces Coal, Geothermal Overtakes Gas As Major Sources Of Power Generation In New Zealand. Clean Technica. Retrieved from http://cleantechnica.com/2015/03/31/wind-replaces-coal-geothermal-overtakes-gas- major-sources-power-generation-new-zealand/
Electrical Engineering portal. (2013, December 6). An overview of the transmission and distribution network of New Zealand. Retrieved from http://electrical-engineering- portal.com/an-overview-of-the-transmission-and-distribution-network-of-new-zealand
EM Watch. (2016). Living close to power lines. Retrieved from http://emwatch.com/power-line- emf/
Parmar, J. (2012, February 17). Effects of high voltage transmission lines on humans and plants. Personal Blog. Retrieved from https://electricalnotes.wordpress.com/2012/02/17/effects- of-high-voltage-transmission-lines-on-humans-and-plants/
Radio New Zealand. (2016, April 11). Living off grid no barrier to modern life. Retrieved from http://www.radionz.co.nz/news/national/301181/living-off-grid-no-barrier-to-modern-life
Sandhu, E. M. & Thakur, D. T. (2014). Issues, Challenges, Causes, Impacts and Utilization of Renewable Energy Sources - Grid Integration. Journal of Engineering Research and Applications, 4(3), 636-643. Retrieved from www.ijera.com
Transpower. (2016). Electricity Demand. Retrieved from https://www.systemoperator.co.nz/security-supply/sos-weekly-reporting/electricity- demand
Transpower. (n.d.). Frequently Asked Questions. Retrieved from https://www.transpower.co.nz/about-us/frequently-asked-questions
