Renewable energy

Solar energy

Solar power is the energy from the sun. It is considered Renewable because the technology used to convert the sun’s power into electricity does not produce smoke, such as carbon dioxide and other air pollutants.
Solar power can be captured from either solar cells or solar panels. Solar cells are devices that convert light energy directly into electrical energy. Solar panels are different, they do not generate electricity directly, they heat up water that a pump pushes through pipes. This can go from being in a house roof to a bigger scale like heating water into steam to turn turbines to produce electricity.

solar
Photo credit: inhabitat

We harness the sun’s energy in several ways. Passive solar design is the use of solar radiation to heat our buildings. Those that are specifically passive solar designed make best use of this. Solar panels, also known as photovoltaic (PV) panels, generate electricity directly from sunlight. Another technology, solar water heating, uses the sun to heat water.
Solar technology is silent and unobtrusive, and can be used all around the country. The main barrier to its uptake is cost.
Large scale wind, geothermal and hydro are renewable options that generate electricity much more cheaply than domestic solar.
Solar generation is currently a small proportion of New Zealand’s energy supply, making up only 0.1% of our total renewable energy. Price reductions in solar PV equipment have made it more popular with homeowners and businesses, despite the fact that it generally remains more costly than grid-supplied electricity.

In 2011, the International Energy Agency said that “the development of affordable, inexhaustible and clean solar energy technologies will have huge longer-term benefits. It will increase countries’ energy security through reliance on an indigenous, inexhaustible and mostly import-independent resource, enhance sustainability, reduce pollution, lower the costs of mitigating global warming, and keep fossil fuel prices lower than otherwise. These advantages are global. Hence the additional costs of the incentives for early deployment should be considered learning investments; they must be wisely spent and need to be widely shared”.

Solar power in New Zealand currently contributes less than 0.1 percent to the country’s overall electricity generation. In the 2015 calendar year, an estimated 33 GWh of solar-generated electricity was contributed to the national grid, out of a total of 42,928 GWh.
Although there are no subsidies, the declining costs of photovoltaics has caused a large increase in demand over the last few years. In 2009, the average turnkey price for a standard PV system of three kilowatts (kW) was about NZ$40,000, and has since dropped by 75 percent to NZ$10,000 (US$7,800 or US$2.60/W).
Sources: EECA, Sustainable Electricity Association New Zealand, eschooltoday.com, Wikipedia

Wind Power

Wind is a form of solar energy because it is mainly caused by changes in the atmosphere by the sun. Wind energy and wind power describe the process by which the wind is used to generate mechanical power or electricity. Wind turbines are responsible for converting the kinetic energy of the wind into mechanical power that can be used for specific tasks, like a generator used to convert this mechanical power into electricity for homes. The wind turbines turn the moving air and power electric generators.

Wind energy is a free and renewable resource that produces clean and non-polluting electricity.
Even though the cost has decreased in the past 10 years, it requires a high initial investment. Compared to fossil fuel plants, wind power plants have relatively little impact on the environment, but there is some concern over the noise produced by the rotator blades that are moved by the wind.

wind
Photo credit: Cleantechnica

One of the major challenges of wind power is that it is intermittent and cannot be stored (although wind-generated electricity can be stored if batteries are used) and not all winds can be harnessed to meet the electricity demands. Location is the key for the development of wind power.

New Zealand has 19 wind farms either operating or under construction. These wind farms currently have a combined installed capacity of 690 megawatts. They supply about 5% of New Zealand’s annual electricity generation, which is about the same amount of electricity as 300,000 kiwi homes use in a year.

Wind power in New Zealand generates a small but rapidly growing proportion of the country’s electricity. Having only become an established generation source in the late 1990s, as of 2012, wind power accounts for 622 MW of installed capacity and nearly 5 percent of electricity generated in the country.

New Zealand is in the path of the Roaring Forties (strong westerly winds found in the Southern hemisphere in this latitude), creating an excellent resource for wind generation. The funnelling effect of Cook Strait and the Manawatu Gorge exacerbate the resource’s potential, making the Lower North Island the main region for wind generation – 70 percent of the nation’s current installed capacity lies within this region, with some turbines recording over 50 percent capacity factor in this area.
Sources: Wikipedia, Wind Energy Development Programmatic EIS, EECA

Hydro power

Hydropower or water power is power derived from the energy of falling water or fast running water, which may be harnessed for useful purposes. Since ancient times, hydropower from many kinds of watermills has been used as a renewable energy source for irrigation and the operation of various mechanical devices.

hydro
Photo credit: Te Ara The Encyclopedia of New Zealand

Hydroelectric schemes use gravity to drive water through turbines, converting that energy into electricity.
Schemes need continuous, year-round water supplies and vertical drops for water to fall down. Water from streams, rivers or dams flows down steep pipes into turbines, which drive power generators. The water then flows back into a river or stream below the hydro plant.
Even if water stored in dams can be turned into electricity in minutes causing no greenhouse gases, the building of the dams has great impact on the environment. The dam wall itself blocks fish migrations breaking species habitats and predation systems. Dams also traps sediments that are critical for maintaining certain habitats downstream. Also, the obvious impact is that they transform the upstream from a free flowing river ecosystem to an artificial slack water reservoir, changing temperature and chemical conditions, losing also farmland and villages.

In the 20th century New Zealand governments created lakes and diverted rivers so electricity could be generated in large-scale hydro schemes. But since public outcry over the raising of Lake Manapōuri in the 1960s, large hydroelectricity schemes have been opposed by environmentalists, tourist operators, fishermen and locals.

The generation of electricity from hydro energy is well established in both the North and South Islands of New Zealand. It is the most common way to produce electricity in New Zealand because of our many waterways and mountains. In 2009, New Zealand’s total hydro capacity was 5400 MW: approximately 3500 MW in the South Island and 1900 MW in the North Island.
Sources: Te Ara The Encyclopedia of New Zealand, EECA, Internation Rivers, Wikipedia, Electrocity

Geothermal energy

Geothermal energy is the heat from the Earth. It is clean and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth’s surface, and down even deeper to the extremely high temperatures of molten rock called magma.

Almost everywhere, the shallow ground or upper 10 feet of the Earth’s surface maintains a nearly constant temperature between 10° and 16°C. Geothermal heat pumps can tap into this resource to heat and cool buildings. A geothermal heat pump system consists of a heat pump, an air delivery system (ductwork), and a heat exchanger-a system of pipes buried in the shallow ground near the building. In the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air delivery system. In the summer, the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger. The heat removed from the indoor air during the summer can also be used to provide a free source of hot water.

geothermal
Photo credit: New Zealand Geothermal Association

Geothermal fluids also contain gases and minerals, though amounts vary from field to field, and the amount released depends on the design of the power station. Electricity generated from geothermal energy does produce some greenhouse gas emissions. However, geothermal power station emissions still produce fewer greenhouse gas emission than the cleanest natural gas-fuelled power stations.

Geothermal energy produces about 13% of New Zealand’s electricity supply. Most of New Zealand’s installed geothermal generating capacity of about 750 MWe is situated in the Taupo Volcanic Zone, with another 25 MWe installed at Ngawha in Northland.
Sources: New Zealand Geothermal Association, EECA, Renewable Energy World