Committee on Climate Change sees role for ammonia enabling Hydrogen for a Low-Carbon Economy
By on December 21, 2018
In the UK, an expansive report was published last month that examines the role of Hydrogen in a low-carbon economy. It considers ammonia’s role in depth, both as a potential low-cost hydrogen carrier and as a direct fuel.
As a hydrogen carrier, “converting hydrogen to ammonia as a means of transporting it over long distances would have lower costs than transporting it as hydrogen.” And used directly, ammonia is “a hydrogen-rich liquid that could be used as an alternative or complementary fuel.”
The Committee on Climate Change (CCC) is an independent, statutory body, established in the UK by the Climate Change Act 2008, that provides “advice to government on building a low-carbon economy and preparing for climate change.”
This latest report on hydrogen, published alongside similar assessments of biofuels, land-use changes, and coastal management, concludes that “hydrogen is a credible option to help decarbonise the UK energy system but its role depends on early Government commitment and improved support to develop the UK’s industrial capability.”
While the report assesses the potential of hydrogen and ammonia to decarbonize the buildings, transport, and industry sectors, much of its focus is on the role of hydrogen in the power sector.
It appears technically possible that new power stations could be built to burn hydrogen, ammonia or a combination of the two, at limited additional cost. Modest retrofits to some existing power stations could also make burning these zero-carbon fuels viable. It is possible to already burn these fuels in engines … [but] burning hydrogen in power stations is only likely to be viable if there is a low-cost route to getting sufficient volumes of fuel to the power stations …
Hydrogen could be produced at low cost at locations outside of Europe (e.g. from gas reforming in the Middle East, or from solar power near the equator). This would need to be imported via ships, either as hydrogen or another energy carrier such as ammonia.
Committee on Climate Change, Hydrogen in a low-carbon economy, November 2018
The CCC’s economic analysis explains the attraction of ammonia for low-carbon energy imports. When used as a hydrogen carrier, including the final energy-intensive dehydrogenation step, the cost of hydrogen supplied as ammonia is competitive against the cost of using liquefied hydrogen or liquid organic hydrogen carriers.
However, when used as a direct fuel, ammonia offers a potential 30% cost reduction. The CCC estimates the UK’s domestic hydrogen cost to be £38/MWh by 2050 (based on natural gas reformation with carbon capture and sequestration). Importing ammonia from low-cost producers using the same technology, and using the ammonia directly, would achieve a “hydrogen cost” of £27/MWh.
Much of the attraction of hydrogen and ammonia, in the power sector, comes from its ability to provide “long-duration energy storage in order to meet seasonal peaks in electricity demand,” which, in turn, helps to “accommodate variable renewable energy within the system.”
By 2030, the UK is likely to have a very low-carbon electricity system, with renewables and nuclear backed up by flexible thermal capacity – mainly natural gas plants. There is an opportunity for hydrogen to replace natural gas cost-effectively in this back-up role, potentially enabling power system emissions to get close to zero by the 2040s. This would be helped if new gas plants can be made ‘hydrogen ready’, including being well-sited with respect to potential hydrogen supplies …
If hydrogen and/or ammonia can be combusted (at high efficiency) in gas power stations to produce electricity, then it is likely this could play a similar role to natural gas power plants today: providing capacity, flexible generation and a range of essential power system services such as inertia, and frequency response.
As carbon prices rise, the economics of burning low-carbon gas for power generation improve. We estimate that burning hydrogen in power stations will be cost-effective against the government’s carbon values in the 2030s.
Committee on Climate Change, Hydrogen in a low-carbon economy, November 2018
The CCC report identifies three viable routes to producing low-carbon hydrogen: electrolysis using low-carbon electricity, bioenergy with CCS (BECCS), and natural gas with CCS. However, its analysis sees electrolysis as having a “relatively small” potential impact on hydrogen volumes, “due to low efficiency [and] challenging build rates.” Therefore, the report’s vision for hydrogen in the UK’s future low-carbon economy relies heavily on CCS, which is an as-yet-unproven technology in the UK.
This leads to the CCC’s call to action, encouraging the government to make big, long-term decisions in the short-term, recognizing its limited information. It characterizes these as “low-regret” deployment decisions, which support the establishment of a domestic hydrogen industry, and avoid reliance upon external markets – which may or may not materialize in the future.
Without CCS therefore, hydrogen is likely to be limited to niche applications unless a large-scale international market in low-carbon hydrogen (e.g. carried as ammonia) emerges. Such an international market cannot be relied upon and is unlikely to occur in the next 10-15 years, during which time key decisions on the role of hydrogen must be made …
If hydrogen is to play a substantial long-term role, progress towards deployment of low-carbon hydrogen at scale must start now. Deployment of hydrogen should start in a ‘low-regrets’ way over the next decade, recognising that even an imperfect roll-out is likely to be better in the long term than a ‘wait-and-see’ approach that fails to develop the option properly.
Committee on Climate Change, Hydrogen in a low-carbon economy, November 2018