Is eco-friendly gas in your home just a pipe dream?
Electricity is an efficient and cheap replacement for natural gas. It’s time to electrify every new home and building, some experts think. By Olivia Wannan.
IF you’re renovating or building a home, you can cut your carbon footprint by choosing electricity over natural gas.
Although this fossil fuel may be scarcer by 2030, new customers can still connect to the gas network. Electricity companies, who say their fuel is the cheaper and greener alternative, think it’s time to ban new gas connections.
The gas companies say it’s possible to produce zero-carbon gas. Yet even when it arrives, it’ll be in short supply – and you’ll need to pay a premium. One green gas, hydrogen, comes with worrying safety risks.
Based on today’s technology, electricity is the greener choice. Because of that, Ecotricity chief executive Al Yates wants the Government to ban new gas installations.
‘‘No one likes a ban, but we’re getting to the point where we don’t really have a lot of options. We have to stop emissions straight away,’’ he said. ‘‘If you tell the country there will be a ban on new installations in a couple of years’ time, at least it gives businesses ... time to adjust.’’
Yates said an average home using gas for heating and cooking emits 1400 kilograms of the greenhouse gas carbon dioxide a year – about equal to 7500 kilometres in a small car.
Provided by the national grid, the same amount of electricity would produce around 700kg of carbon dioxide, according to Toitu¯ Envirocare’s carbon calculator.
However, the emissions are likely to be even lower.
Electrical appliances – particularly those using heatpump or induction tech – are more efficient than gas versions, said Energy Efficiency and Conservation Authority (EECA) strategy, insights and regulations group manager Marcos Pelenur. ‘‘They’re getting better all the time.’’
Created underground from decomposing plants and animals, natural gas is a form of methane – although shorterlived than other greenhouse gases, it’s very potent. LPG (or liquid petroleum gas) is a mix of butane and propane, which are by-products of natural gas refinement.
The delivery method can help you tell them apart – natural gas reaches homes in the North Island through a piped network, whereas LPG is delivered in bottles. Approximately 450,000 homes and businesses use one of the two gases, according to natural gas network operator First Gas.
Households produce about 360,000 tonnes of carbon dioxide each year by burning gas, according to government estimates.
However, the carbon footprint of gas extends beyond the fuel that reaches your heater or stovetop. Gas extraction and processing also releases additional carbon dioxide – for example, through the flares at the top of wells.
Together, oil and gas production in New Zealand emitted 900,000 tonnes of carbon dioxide in 2018 – though there’s no separate figure for gas. On top of that, the equivalent of 200,000 tonnes of carbon dioxide was lost from natural gas escaping as it moved through the network. Finally, there’s the fuel used for transport.
Our electricity also has a carbon footprint, as about 20 per cent of the country’s power is created by burning natural gas and coal each year. The fossilfuelled generators often have to be switched on when residential
demand for power peaks, typically on winter mornings and evenings.
Even so, an EECA analysis in 2013 found electricity is a greener choice than natural gas, even taking into account fossilfuelled power plants working harder during winter peaks if homes made the switch.
To cut emissions, cities across the US – including San Francisco – have banned the use of natural gas in new houses and buildings. The UK is set to follow suit for fossil-fuelled boilers in the 2030s. The move may also improve health, as gas appliances can release pollutants and increase condensation.
Our Government is currently assessing how to build warmer, drier, lower-carbon and more climate-resilient homes.
Residential homes burn just over 3 per cent of the country’s gas each year. The largest consumers are chemical plants and electricity generators.
The Government’s 2018 ban on new offshore gas exploration could start to bite at the end of the decade. The last exploration permits for gas fields end in 2030. Based on steady demand and no new discoveries, the International Energy Agency estimated back in 2017 that Aotearoa had 10 years of natural gas reserves – though any shortage may influence other users before homeowners.
However, a lot could change between now and then, said First Gas strategy and corporate development group manager Angela Ogier.
‘‘You can drill an extra well, you can recomplete wells – lots of little things you can to do eke out more gas. But it’s all about who’s going to pay for it and whether there’s a market.’’
Genesis Energy is expecting sales of natural gas to drop in the coming years. As part of its efforts to decarbonise, the energy supplier and power generator is helping its large commercial and industrial customers to switch from gas to electricity, a company spokesperson said.
The company said residential customers won’t be affected, but ‘‘obviously over the long term, the Government’s stated goal for all New Zealanders is to reduce the use of carbon-intensive fuels and transition to renewable energy solutions’’.
The Government has also stumped up $70 million to help businesses switch away from gas- and coal-powered heating systems.
Alongside electricity, other green alternatives are biomethane (natural gas made from organic waste) and hydrogen gas.
Yet both fuels are in their infancies. There’s a pilot project currently underway to understand how feasible biomethane production would be. But it’s unlikely we’ll ever produce enough to replace natural gas entirely – and high demand for what we can make could drive up prices.
The first carbonfree hydrogen production plant will go online this year, though the gas will need to be mixed with at least 80 per cent natural gas or biomethane to be used in the existing gas pipelines and home appliances.
Pure hydrogen gas is very
‘You can do all these little things to eke out more gas. But it’s all about who’s going to pay for it and whether there’s a market.’ ANGELA OGIER
unlikely to be piped into homes, said process and energy engineer Johann Land. That would require a complete replacement of the pipe network and home appliances.
‘‘Why would you do that when you could just use electricity?’’ he said.
Then there are the safety issues. Hydrogen explodes at a wider range of concentrations compared to natural gas, Land said.
‘‘The energy it takes to explode hydrogen is way smaller than natural gas. For natural gas you would need an actual spark, whereas for hydrogen all it takes is the equivalent energy of rubbing – static electricity is enough to explode hydrogen. If that leak happens in an enclosed space, let’s say a room, a house, that’s begging for a disaster.’’
Electricity is already widely available and trusted – though we’ll need to upgrade the insulation in existing homes as we switch away from gas, Land said.
Green gas expert Andrew Clennett, chief executive of Hiringa Energy, said green hydrogen will be better suited for some applications, such as replacing diesel in large trucks.
The future cost of electricity and green gas will help determine which low-carbon fuels power our homes – as will consumer preference, he said.
Hydrogen can be used in multiple ways: burned (as on a cooking hob) or in the chemical reactions taking place in a fuel cell (powering a car, truck or plane).
‘‘Don’t get me wrong, burning the hydrogen molecule is not the best use of the hydrogen molecule,’’ he added.
‘‘We’re kidding ourselves if we think we know how that will all relatively stack up. But what we do need to do is decarbonise, stop the fossil carbon.’’
Both the proponents of hydrogen and electricity said we’ll need to make better use of nighttime electricity generation, using it to power electric systems and create hydrogen.
Some US cities experienced a backlash after they banned natural gas, particularly from restaurant associations and poverty rights groups.
Instead of a ban or moratorium, Clennett suggested any gas connections in new homes and buildings could be required to have a certified zerocarbon gas supply.
‘‘The people that do want that gas can get that gas, but they’ve got to pay a bit of a premium for it,’’ he said. ‘‘You don’t want to expand the natural gas market.’’
Pelenur said the climate impact of a new home is about more than the choice of electricity or gas. The building materials, level of insulation and location all play a role. A development far from lowcarbon transport options could have a heavier impact on carbon emissions even if it had no gas.
‘‘If we’re going to transition to a zero-carbon economy, we’ll probably need to do a number of things.’’