Aug 30, 2013

Converting Biomass to Hydrogen Fuel

4 min
The utilization of biomass can be traced back thousands of years, when our smart ancestors first started burning wood to make fire, turning a new p...

The utilization of biomass can be traced back thousands of years, when our smart ancestors first started burning wood to make fire, turning a new page in human history. Since then, biomass had become the main source of energy for daily use and greatly contributed to the development of society.

Although the wide application of fossil fuels since the 19th century slowed down the development of biomass related technology, biomass has made a resurgence in the early 21st century due to a growing preference for creating fuels from renewable sources.

As a result, steam reformation technology was developed to convert biomass to hydrogen fuel, which as a fuel possesses higher energy density and is more environmentally friendly when burned than biomass. This conversion technology uses an anaerobic digester to produce methane from biologically treated biomass material such as chaff, wood pulp, trimmings, dung, biomass garbage, etc., followed by using steam methane reforming equipment to produce hydrogen fuel with carbon monoxide as the byproduct, which is also known as syngas.

One important application of hydrogen fuel is using polymer electrolyte membrane (PEM) fuel cells. PEM fuel cells can directly convert chemical energy to electrical energy with water as the only emission, thus minimizing the energy loss and is considered as a “green energy” device. Since they can be operated under a low temperature range (50-100 °C) and are easy to be customized, PEM fuel cells are developed for vehicle, portable and stationary fuel cell applications.

The reactions in PEM fuel cells are hydrogen oxidation and oxygen reduction. To initiate both reactions under low temperature, a platinum catalyst is mandatory, which is considered to be the most active catalyst for the reactions in PEM fuel cells. However, platinum catalysts are very sensitive to the impurities in hydrogen fuel, especially carbon monoxide. Even 30 ppm of carbon monoxide can cause a 48 percent drop in the output cell voltage of a PEM fuel cell1 and 90 percent voltage drop is observed for the existence of 100 ppm carbon monoxide2. Therefore, if we want to use hydrogen fuel produced from biomass by SMR technology, it is necessary to get rid of carbon monoxide in the syngas (20-25 percent in volume) as much as possible.

In order to remove carbon monoxide from the hydrogen fuel generated from biomass, a purification system is employed. Steam is used to trigger a water gas shift (WGS) reaction for oxidizing most of the carbon monoxide to carbon dioxide. However, since the WGS reaction is a reversible reaction, it is very difficult to keep the reaction going at the direction we want when the concentration of carbon monoxide is relatively low (but still higher than the acceptable concentration).

To solve this problem, pressure swing adsorption (PSA) technology comes up and finally increases the purity of hydrogen to more than 99.99 percent. This technology relies on the gas adsorption to solid surfaces under high pressure. Moreover, this adsorption is very selective based on the materials of the solid surface.

Therefore, if an adsorbent bed that can strongly absorb carbon monoxide but not hydrogen as well is placed in the chamber and the syngas previously purified by WGS reaction flows through it, high purity hydrogen can be collected. Meanwhile, since the surface area of adsorbent material is limited, more than one absorbent chamber is needed for the continuous production. To keep the absorption efficiency, a gas release process is necessary while the chamber is not in use.  In light of these issues, system design and modeling become extremely important to efficiently purify the hydrogen fuel.

The most recent technology designed for hydrogen generating by methane (main product generated from biomass by SMR technology) reforming with PSA purification system can treat up to 20000 m3 gas per hour and produce extremely pure hydrogen with up to 99.999 percent purity, meeting standards for PEM fuel cell applications. For example, Verde LLC in Boston has developed this type of system, and made it customizable for different purposes of use, such as to build a home fuel cell station by utilizing highly pure hydrogen generated from biomass.

Think about it: if all the houses along the eastern coast were installed with this biomass-fuel cell station, most people would not have suffered from that long power outage caused by Hurricane Sandy at all. Besides, the integration of such station could reduce a lot of carbon release and finally save our world from global warming effect.

Verde LLC is a technology manufacturer based in Braintree, Mass. Verde LLC specializes in designing and deploying residential, commercial, and industrial scale electrolyzers used for: renewable energy storage, industrial processing, transportation fuel, natural gas plant peaking and cooling, fertilizer manufacture and distributed generation. They have an extensive network with national laboratories, commercial/industrial partners, and universities as well as products in operation around the world. 

1.    C.M. Seymour. L Power Sources 37, 155 (1992)

2.    R.A. Lemons. J. Power Sources 29, 251 (1990).  

Share article

Jun 25, 2021

UK must stop blundering into high carbon choices warns CCC

Dominic Ellis
5 min
The UK must put an end to a year of climate contradictions and stop blundering on high carbon choices warns the Climate Change Committee

The UK Government must end a year of climate contradictions and stop blundering on high carbon choices, according to the Climate Change Committee as it released 200 policy recommendations in a progress to Parliament update.

While the rigour of the Climate Change Act helped bring COP26 to the UK, it is not enough for Ministers to point to the Glasgow summit and hope that this will carry the day with the public, the Committee warns. Leadership is required, detail on the steps the UK will take in the coming years, clarity on tax changes and public spending commitments, as well as active engagement with people and businesses across the country.

"It it is hard to discern any comprehensive strategy in the climate plans we have seen in the last 12 months. There are gaps and ambiguities. Climate resilience remains a second-order issue, if it is considered at all. We continue to blunder into high-carbon choices. Our Planning system and other fundamental structures have not been recast to meet our legal and international climate commitments," the update states. "Our message to Government is simple: act quickly – be bold and decisive."

The UK’s record to date is strong in parts, but it has fallen behind on adapting to the changing climate and not yet provided a coherent plan to reduce emissions in the critical decade ahead, according to the Committee.

  • Statutory framework for climate The UK has a strong climate framework under the Climate Change Act (2008), with legally-binding emissions targets, a process to integrate climate risks into policy, and a central role for independent evidence-based advice and monitoring. This model has inspired similarclimate legislation across the world.
  • Emissions targets The UK has adopted ambitious territorial emissions targets aligned to the Paris Agreement: the Sixth Carbon Budget requires an emissions reduction of 63% from 2019 to 2035, on the way to Net Zero by 2050. These are comprehensive targets covering all greenhouse gases and all sectors, including international aviation and shipping.
  • Emissions reduction The UK has a leading record in reducing its own emissions: down by 40% from 1990 to 2019, the largest reduction in the G20, while growing the economy (GDP increased by 78% from 1990 to 2019). The rate of reductions since 2012 (of around 20 MtCO2e annually) is comparable to that needed in the future.
  • Climate Risk and Adaptation The UK has undertaken three comprehensive assessments of the climate risks it faces, and the Government has published plans for adapting to those risks. There have been some actions in response, notably in tackling flooding and water scarcity, but overall progress in planning and delivering adaptation is not keeping up with increasing risk. The UK is less prepared for the changing climate now than it was when the previous risk assessment was published five years ago.
  • Climate finance The UK has been a strong contributor to international climate finance, having recently doubled its commitment to £11.6 billion in aggregate over 2021/22 to 2025/26. This spend is split between support for cutting emissions and support for adaptation, which is important given significant underfunding of adaptation globally. However, recent cuts to the UK’s overseas aid are undermining these commitments.

In a separate comment, it said the Prime Minister’s Ten-Point Plan was an important statement of ambition, but it has yet to be backed with firm policies. 

Baroness Brown, Chair of the Adaptation Committee said: “The UK is leading in diagnosis but lagging in policy and action. This cannot be put off further. We cannot deliver Net Zero without serious action on adaptation. We need action now, followed by a National Adaptation Programme that must be more ambitious; more comprehensive; and better focussed on implementation than its predecessors, to improve national resilience to climate change.”

Priority recommendations for 2021 include setting out capacity and usage requirements for Energy from Waste consistent with plans to improve recycling and waste prevention, and issue guidance to align local authority waste contracts and planning policy to these targets; develop (with DIT) the option of applying either border carbon tariffs or minimum standards to imports of selected embedded-emission-intense industrial and agricultural products and fuels; and implement a public engagement programme about national adaptation objectives, acceptable levels of risk, desired resilience standards, how to address inequalities, and responsibilities across society. 

Drax Group CEO Will Gardiner said the report is another reminder that if the UK is to meet its ambitious climate targets there is an urgent need to scale up bioenergy with carbon capture and storage (BECCS).

"As the world’s leading generator and supplier of sustainable bioenergy there is no better place to deliver BECCS at scale than at Drax in the UK. We are ready to invest in and deliver this world-leading green technology, which would support clean growth in the north of England, create tens of thousands of jobs and put the UK at the forefront of combatting climate change."

Drax Group is kickstarting the planning process to build a new underground pumped hydro storage power station – more than doubling the electricity generating capacity at its iconic Cruachan facility in Scotland. The 600MW power station will be located inside Ben Cruachan – Argyll’s highest mountain – and increase the site’s total capacity to 1.04GW (click here).

Lockdown measures led to a record decrease in UK emissions in 2020 of 13% from the previous year. The largest falls were in aviation (-60%), shipping (-24%) and surface transport (-18%). While some of this change could persist (e.g. business travellers accounted for 15-25% of UK air passengers before the pandemic), much is already rebounding with HGV and van travel back to pre-pandemic levels, while car use, which at one point was down by two-thirds, only 20% below pre-pandemic levels.

Share article