Gas has a part to play in the integration of renewable energy and the reduction of carbon dioxide emissions. But decarbonisation efforts must intensify if it is to retain a significant role in a future, sustainable energy mix.
With considerably lower carbon dioxide emissions (CO2) than coal and oil, natural gas is often seen as an instrument for weaning the world off its fossil fuel dependence, easing the way to a decarbonised future. Natural gas can also contribute to the smooth functioning of the power system through its long-term storage capabilities and flexibility, with modern gas plants able to quickly ramp up and down to respond to changes in output of variable renewable energy generation, facilitating their integration in the electricity mix. Natural gas is, however, far from being the only flexibility mechanism available for the power system. Moreover, like coal and oil it is also a fossil fuel and will have to be decarbonised or replaced by so-called green gases if international climate commitments — namely the Paris agreement to keep the global temperature rise to below 2°C — are to be met. “Natural gas has an important role to play as part of a diversified portfolio,” believes David Littell of the Regulatory Assistance Project (RAP), a global group of former regulators offering energy policy advice. “But it’s important not to over invest. In the long term, all fossil fuels will have to decrease dramatically.”
Short bridge
“Even the role of natural gas as a bridge to renewables is a short one unless natural gas use is coupled with high levels of CCS [carbon capture and storage],” the International Renewable Energy Agency (IRENA) says in its 2017 joint energy transition study with the International Energy Agency (IEA).The study warns of the risk of, “Path dependency and future stranded assets, such as pipelines and liquefied natural gas terminals [LNG], if natural gas deployment expands significantly without long-term reduction emissions goals in mind,” leaving infrastructure unused and investors out of pocket. CCS, in which carbon dioxide is captured and stored underground, has not advanced far to date. A lack of support from policymakers and investors, who have favoured technologies considered to be more secure like wind and solar, plus low carbon prices, has held back investments. Yet the European Academies Sciences Advisory Council (EASAC) suggests in a recent report that the world will miss its target to limit the temperature rise to 2°C without CCS. DNV GL, a Norwegian-German risk management company agrees with this assumption. In January 2018 it launched a framework for certifying the geological storage of carbon dioxide and a recommended practice for the design and operation of CO2 pipelines in an attempt to improve dialogue and investor predictability around CCS. DNV GL’s 2017 Energy Transition Outlook lays out a single, “most likely” scenario rather than targeting a desired outcome. In the scenario, natural gas surpasses oil and coal to become the world’s largest primary energy source in about 2035. The scenario also sees gas peaking in 2035 at a level 14% greater than in 2017, before experiencing a moderate decline as renewables increasingly dominant the electricity market.
Fuel switching
Meantime, switching to natural gas from other more polluting fuels may be an appropriate short and medium-term solution in some places and sectors. The shift to natural gas and away from coal in countries like the US and the UK has contributed to cutting carbon dioxide emissions. “It makes sense to start fighting emissions from coal before you start fighting emissions from gas, even though gas is still only a partial decarbonising solution,“ says Sverre Alvik, who heads DNV GL’s research on the energy transition. Yet even partial solutions are not always easy to achieve, with some countries still tempted to use coal. “Our perspective in northwest Europe is massively climate-centred, but this view isn’t shared by much of the world,” explains Jonathan Stern, distinguished research fellow and founder of the natural gas programme at the Oxford Energy Institute in the UK. “For most countries, the priorities are energy security, affordability and access to energy. In that context, gas still faces problems in much of the world because of affordability issues.” At the same time, Littell of RAP points to a “fervent debate” about the best strategy to pursue in some emerging markets and whether it might make more sense to push more for renewables when decommissioning polluting coal or diesel plants and a little bit less for gas. “There are big questions about the extent you should shift to natural gas. If you import LNG, you need import terminals and that is substantial infrastructure. There are also substantial energy losses if you have to liquefy and regassify so it’s less climate friendly,” he says. In the European Union, renewable energy accounted for over 30% of total power generation in 2017 while 50% is targeted for 2030 and the power sector is expected to be nearly completely decarbonised in 2050. As a power sector with 100% renewables is no longer seen as an unachievable task, attention is gradually shifting to heating and transport, where increasing the share of green energy is seen as more difficult. Electrification could help increase the weight of green energy in these sectors as well, but many observers also expect gas to play an important role. While there is a growing consensus that electric vehicles will dominate the future passenger car market, natural gas and other alternative fuels could carve out a stronger position in the trucking and maritime sectors. Natural gas vehicles (NGVs) open the way to renewable NGVs powered by compressed biomethane or liquefied biomethane and based on the development of local resources as part of a circular economy, according to Sylvie Cornot-Gandolphe, a research associate with French think tank IFRI and author of a January 2018 report on the role of gas in the European energy transition. Gas will also retain a significant role in heating, which accounted for some 41% of European gas demand in 2016, she says. “The European gas network, already well developed and integrated, can transport energy at a cost much lower than new electric infrastructure and gas storage capabilities can manage the seasonality and the variability of demand.” As is the case for transport, natural gas could be replaced in heating by renewable versions.
On a global level, if you were to take all the food waste that is thrown away and make biogas, it would be equivalent to taking every car off the road in Europe and removing 500 million tonnes of CO2
Biogas potential
There are a number of potential paths to a cleaner gas future, including the development of biogas. Among renewable gas alternatives, biogas produced from the anaerobic digestion of biomass is the most advanced, although penetration varies greatly depending on the incentives in place. Frontrunners in biogas use include sewage treatment facilities, which need energy to run and have a convenient source in wastewater sludge. Farmers have also produced biogas in small-scale facilities fuelled by manure and other agricultural waste to provide power to their farms. The industry is now increasingly scaling up, forcing costs down. Biogas can be upgraded to biomethane to be used in the grid and as a clean fuel source in transport. Finland’s Gasum earlier this year opened a filling station at an IKEA furniture store selling biomethane from waste produced at the retailer’s restaurant. Italy has introduced incentives for both biomethane and liquid biofuels as it aims to reach a 2020 target for 10% renewable energy in transport. The city of Nottingham, in central England, recently rolled out what it claims is the world’s largest biogas bus fleet, just a few years after UK waste management and renewable energy group GENeco debuted its Bio-bus, also known as the “poo bus,” the first bus in the UK to be powered by gas derived from food, sewage and commercial liquid waste. “There is enormous potential in biogas,” says David Newman, president of the World Biogas Association (WBA). “On a global level, if you were to take all the food waste that is thrown away and make biogas, it would be equivalent to taking every car off the road in Europe and removing 500 million tonnes of CO2.” Newman expects biogas use in the EU to more than double to some 70 million tonnes of oil equivalent (mtoe) in 2030 from 30 mtoe now, but remain far below the potential he sees of some 140 mtoe for that year. Energy group Engie also has high expectations of renewable gas, estimating that biogas from agricultural and other wastes could grow in France, for example, from about 1% of gas consumption now to 10% in 2025 and 30% by 2030 before hitting 100% by 2050.
Danish lessons
Lessons could be learned from Denmark, which already covers 10% of gas demand with biogas and has committed to being free of fossil fuels by the middle of the century. Trade association Green Gas Denmark, using estimates from Aarhus University, believes the country’s gas grid could be 100% green as soon as 2035. Ole Hvelplund, CEO of Danish Nature Energy, says biogas growth in Denmark has been supported politically through a bipartisan 2012 energy agreement and subsidies, which reduce in increments over time. “We need subsidies at the moment, but we are trying to reduce costs in all processes to make this technology more commercial,” he says. “Denmark has a target to become independent of fossil fuels and so it’s not a question of if but how we get renewable resources in the gas system,” says Jeppe Danø, market director for gas at Danish gas and power transmission system operator Energinet.dk. He points to the benefits of coupling electricity and gas. “We have a huge amount of flexibility in the gas system, a storage capacity of one billion cubic meters of gas, equivalent to about one billion Tesla batteries, that can provide a large degree of flexibility for both electricity and heating.” Via Denmark’s combined heat and power plants, renewable biogas can be injected into the power system, primarily for peak production needs. “Providing power from biogas doesn’t make much sense a lot of the time because there are other renewable sources like wind and solar that are cheaper, but there is role for it to play when the wind is not blowing and the sun is not shining,” says Hvelplund. Energinet.dk’s Danø anticipates power-to-gas technology will mature in the next decade or so, a development he sees being facilitated by the sharp drop in electricity prices due to the introduction of more wind and solar. “By 2050, we think it is realistic that biogas, power-to-gas and also gas created from synthetic processes will all be feasible price-wise,” he says.
We’ve talked a lot, so either we need to stop talking or someone has to move forward with a commercial scale project
Green hydrogen
Hopes for power-to-gas, which could provide one option for storing renewable electricity in excess of immediate demand, are largely pinned on hydrogen. Hydrogen is free of greenhouse gas emissions and potentially an enormous contributor to decarbonisation efforts, but uncertainty about the possibility of scaling is high. Hydrogen has traditionally been produced from natural gas through a steam reforming process that requires a CCS mechanism to be considered as a clean energy source. Attention now is increasingly focused on green hydrogen produced by the electrolysis of water powered by wind and solar photovoltaic facilities. “Either way you do it, it’s expensive,” says Stern. The lack of a regulatory framework indicating how a hydrogen project could pay back its investment has impeded development, he states. European regulators have begun taking a look at the issue and Stern suggests that now is the time to make a decision about the future of this technology. “We’ve talked a lot, so either we need to stop talking or someone has to move forward with a commercial scale project.” One option to begin the move to a hydrogen gas grid would be to use existing infrastructure, initially blending a 15-20% hydrogen mix into natural gas, a proportion that is generally seen as feasible without needing to change the pipelines. In transport, there is likely to be a niche for hydrogen fuel-cell vehicles, which currently have the advantage over electric vehicles of longer range and quicker fuelling times, although the high costs of the technology and refuelling stations are a big problem. Hydrogen fuel cells could be interesting for long-haul tracking and Toyota last year began testing the world’s first heavy-duty fuel cell truck. Fellow Japanese auto makers Honda and Nissan are also counting on there being a wider market for hydrogen fuel cells and the US state of California plans to have five million zero emission vehicles on its roads by 2030 supported by 200 hydrogen fuelling stations alongside 250,000 electric vehicle charging stations.
Step on the gas
While initial progress has been made in the development of a cleaner gas industry, a massive acceleration in investments is clearly needed if gas is to contribute significantly to a future, decarbonised energy mix. Green gas pioneers are hoping to bring down the costs of technology, following the path already blazed by the wind and solar industries and attracting new capital to accelerate growth. Policymakers can also help, providing initial economic support when appropriate and pursuing measures to prop up the price of carbon penalties, one driver for the creation of decarbonised gas that has been sorely neglected in most places. Although the prospects for large-scale development of technological options like hydrogen and CCS are unclear, their potential should not be overlooked. DNV GL hazards a guess that global temperatures will rise 2.5°C under the scenario laid out in its 2017 Energy Transition Outlook. “We’ve looked at how to close the gap and there is no silver bullet,” says Alvik. “You need a combination of actions: a further uptake of renewables, further energy efficiency and some CCS and other measures to make gas greener.”
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Heather O’Brian