Renewable Hydrogen, an emerging alternative to fossil fuel

Fossil fuels such as coal, oil and gas have helped transformed our power and transport industries for decades till now. But recent geo-political situations, depleting fossil sources and Carbon pollution, global warming and climate change have raised serious questions about the future of fossil fuels. However, countries who have massively invested in fossil fuel infrastructure and who have been heavily relying on supply of fossil fuels have started realizing an inescapable truth that they are running out of time to find an alternative to fossil fuels. Recently Hydrogen has been suggested as an alternative source of energy and many countries are gearing up to promote Hydrogen on a massive scale. The countries who have been traditionally using fossil fuels are now focussing on generating hydrogen from fossil fuels as an easier option. But the basic problem with this approach is they still depend on fossil fuels which means they still contribute to Carbon emission and climate change. They can conveniently dispute or deny the fact that man-made Carbon emissions cause global warming in order to score political points among the ‘gullible public’. Democracy is all about numbers and as along as these number stack up the political parties will take advantage of the system and try to push their agenda. But all these efforts are only short term and they still cannot escape the truth that man made Carbon emission is transforming our world for the worst and the future looks bleak.

However, there is a silver lining in the dark clouds of global warming and climate change in the form of renewable Hydrogen. It is now possible to generate Hydrogen using renewable energy sources such as Hydro, solar, wind, geothermal and OTEC (ocean thermal energy conversion systems) that can used not only decarbonize our present economy and also has the capacity to transform future energy and to a cleaner and more sustainable environment. It is now possible to achieve a circular economy in energy sector which means the CO2 emission from existing and operating power plants using fossil fuels can be reversed using renewable Hydrogen so that one can continue to generate power but with Zero Carbon emission. This is a huge transformation.

However, the usage of fossil fuels will continue in other industries such as petrochemicals, polymers and additives, and other synthetic materials. But one can take advantage of using renewable Hydrogen even in such industries using Green Chemistry initiatives so that they can become more sustainable.

However Renewable Hydrogen is a currently very expensive though it is generated from abundantly available natural resources such as sun, wind and water because PV solar panels are made from high purity silicon material again made from simple sand. We cannot afford to take natural resources lightly because they are precious commodities. With limited usage of renewable energy at current levels the cost of PV solar panels is still very expensive but likely to come down as we deploy more and more solar panels in the future. We should also be careful how we use renewable Hydrogen. Our first and foremost usage of renewable Hydrogen should be to decarbonize the fossil economy and achieve a circular economy. It means we must convert CO2 emissions into renewable natural gas (RNG) suing renewable Hydrogen so that the Carbon can be recycled indefinitely with Zero Carbon emission while power plants using fossil fuels can continue to generate a base load power. By this way we will be able to address two issue namely meeting the rising energy demand at a cheaper price while eliminating global warming and climate change. All other use of renewable hydrogen such as Hydrogen vehicles for transportation using fuel cell etc will be secondary because they are not our priority. If we can generate a base load power (24 x7) using renewable Hydrogen with zero Carbon emission, then that should be our focus whether we believe it climate science or not. This will also help us conserve fossil fuels that may be rarely used to meet certain critical needs while substantially reducing the carbon emission.

Renewable hydrogen will require massive deployment of renewable energy projects all over the world. One can generate renewable energy and use it directly for domestic or commercial use. But they are intermittent and require large scale energy storage. Moreover, all HT transmission lines are old and designed for transmitting base load power. Such an approach will not help decarbonizing fossil economy currently widely used. That is why renewable Hydrogen will have to play a key role in the future energy mix. Renewable hydrogen can be used as a fuel for transport industries using fuel cell and Japan is leading the way in this field. But such an application has along way to go and it requires massive investment and creation of infrastructure by way of filling stations. Countries like Japan do not have vast land area for solar industries, and they are likely to use cheap nuclear power and sea water to generate large scale hydrogen infrastructure. By this way they can supply power to both hydrogen as well as electric (battery) vehicles. Alternatively, they are looking to import liquified hydrogen (LH2) from countries like Australia who are ready to use cheap brown coal to generate Hydrogen by gasification despite CO2 emissions. Currently Australian government is not very keen about cutting CO2 emissions, but they are keen to encourage LH2 from cheap coal. They have already approved a pilot plant in the state of Victoria and only future can tell whether such a decision is prudent or not. Japanese companies may prefer to invest in Australia to generate and export clean liquid hydrogen leaving behind all emissions including CO2 in Australia. They may generate LH2 from natural gas and export it to Japan, but it may not be acceptable by Japanese companies because it has a potential to poison the Platinum catalyst used in their Fuel cell cars. In fact, Australia has an enormous potential to generate renewable hydrogen and then use it locally as well as to export. This will be more sustainable in the long run.

Can alternative energy combat global warming?

The world is debating on how to cut carbon emission and avert the disastrous consequences of global warming. But the emissions from fossil fuels continue unabated while the impact of global warming is being felt all over the world by changing weathers such as flood and draught. It is very clear that the current rate of carbon emission cannot be contained by merely promoting renewable energy at the current rate. Solar, wind, geothermal, ocean wave and OTEC (ocean thermal energy conversion) offer clean alternative energy but now their total combined percentage of energy generation   is only less than 20% of the total power generation. The rate of Carbon reduction by  renewable energy  do not match  the rate of Carbon emission increase by existing and newly built  fossil power generation and transportation, to keep up the current level of Carbon in the atmosphere. The crux of the problem is the rate of speed with which we can cut the Carbon emission in the stipulated time frame. It is unlikely to happen without active participation of industrialized countries such as US, China, India, Japan, EU and Australia by signing a legally binding agreement in reducing their Carbon emissions to an accepted level. However, they can cut their emissions by increasing the efficiency of their existing power generation and consumption by innovative means.

One potential method of carbon reduction is by substituting fossil fuels with biomass in power generation and transportation. By using this method the energy efficiency is increased from current level of 33% to 50-60% in power generation by using gasification technologies and using Hydrogen for transportation. The Fixed carbon in coal is about 70% while the Carbon content in a biomass is only 0.475 X B (B-mass of oven-dry biomass). For example, the moisture content of a dry wood is about 19%,which means the Carbon mass is only 38% in the biomass. To substitute fossil fuels, the world will need massive amounts of biomass. The current consumption of coal worldwide is 6.647 billion tons/yr  (Source:charts bin.com)and the world will need at least 13 billion tons/yr of biomass to substitute coal .The total biomass available in the world in the form of forest is 420 billion tons which means about 3% of the forest in the world will be required to substitute current level of coal consumption. This is based on the assumption that all bioenergy is based on gasification of wood mass. But in reality there are several other methods of bioenergy such as biogas, biofuels such as alcohol and bio-diesel from vegetable oils etc, which will complement biogasification to cut Carbon emission.

Another potential method is to capture and recover Carbon from existing fossil fuel power plants. The recovered Carbon dioxide has wider industrial applications such as industrial refrigeration and in chemical process industries such as Urea plant. Absorption of Carbon dioxide from flue gas using solvents such as MEA (mono ethanolamine) is a well established technology. The solvent MEA will dissolve Carbon dioxide from the flue gas and the absorbed carbon dioxide will be stripped in a distillation column to separate absorbed carbon dioxide and the solvent. The recovered solvent will be reused.

The carbon emission can be reduced by employing various combinations of methods such as anaerobic digestion of organic matters, generation of syngas by gasification of biomass, production of biofuels, along with other forms of renewable energy sources mentioned above. As I have discussed in my previous articles, Hydrogen is the main source of energy in all forms of Carbon based fuels and generating Hydrogen from water using renewable energy source is one of the most potential and expeditious option to reduce Carbon emission.

Fuelcell power using Biogas

Fuel cell technology is emerging as a base-load power generation technology as well as back-up power for intermittent renewable energy such as solar and wind, substituting conventional storage batteries. However, Fuelcell requires a Fuel in the form of Hydrogen of high purity. The advantage of Fuel cell is, its high electrical efficiency compared to conventional fossil fuel power generation technology, using Carnot cycle. Fuel cell is an electro-chemical device like a battery and generates power using electro-chemical redox reaction silently with no gaseous emission, unlike engines and turbines with combustion, rotary movements and gaseous emissions. The fuel Hydrogen can be generated using a renewable energy sources such as solar and wind as described in my previous articles, “Solar Hydrogen for cleaner future” dated 4 July 2012, and “Renewable Hydrogen for remote power supply “dated 28 June 2012.

Alternatively, Hydrogen can also be generated using biomass through Biogas. Biogas is an important source of renewable energy in the carbon constrained economy of today’s world. The biogas can be generated from waste water and agro-waste by anaerobic digestion using enzymes. Biomass such as wood waste can also be gasified to get syngas, a mixture of Hydrogen and Carbon dioxide. In anaerobic digestion, the main product will be methane gas accompanied by carbon dioxide and nitrogen while the main product in gasification will be Hydrogen, carbon monoxide and carbon dioxide and oxides of Nitrogen. Whatever may be the composition of the resulting gas mixture, our focus will be to separate methane or Hydrogen from the above mixture. In anaerobic digestion, the resulting Methane gas has to be steam reformed to get Hydrogen gas suitable for Fuel cell application. In gasification, the resulting Syngas has to be separated into pure Hydrogen and Carbon dioxide so that pure Hydrogen can be used as a fuel in Fuel cell applications. As I have outlined in many of my previous articles, Hydrogen was the only fuel we have used all these years and we are still using it  in the form of Hydrocarbons and it will continue to be the fuel in the future also. The only difference is future Hydrogen will be free from carbon.

We have to discuss two issues to mitigate Carbon emission, and it can be done by 1.Elimination of Carbon from the fuel source. 2. Generation of Renewable and Carbon free clean energy directly from solar and wind. One option  to cut Carbon from the fuel source is to use Biomass as the raw material to generate Hydrogen so that fresh Carbon will not be added  into the atmosphere by emissions .The second option is to generate pure Hydrogen from water by electrolysis using renewable energy such as wind and solar. Environmentally friendly waste-to-energy projects are becoming popular all over the world. But now most of these waste-to-energy projects generate either Biogas (Methane) by anaerobic digestion or Syngas (Hydrogen and Carbon dioxide) by gasification. Both these gases need further purification before they can be used as a fuel for power generation. The Methane content in the Biogas (about 60% methane and 40% Carbon dioxide with other impurities) needs to be enriched to 90% Methane and free from other impurities. The composition of a typical Biogas is shown in table1.

The resulting purified methane gas will be reformed using steam reformation in presence of a catalyst to get syngas; finally Hydrogen should be separated from resulting syngas so that it can be used directly into the Fuelcell.The common Fuel cell used for this application is invariably Phosphoric acid fuel cell.

PAFC uses 100% Phosphoric acid in Silicon carbide matrix as an electrolyte. PAFC is a self-contained unit completely enclosed in a cabin consisting of a gas reformer, Fuellcell power generator, Power conditioning unit and other auxiliaries. The PAFC is of modular construction with capacities ranging from 100Kw up to 500Kw as a single unit. It can be installed outdoor in the open and it can be readily connected to a piped Biogas. It can also be connected to existing piped natural gas or LPG bullet as a stand-by fuel. Any waste-to energy project can be integrated with Fuel cell power generation with CHP application to get greatest economic and environmental benefits. Hydrogen derived from biomass will be an important source of fuel in the future of clean energy; and Fuel cell will become an alternative power generation technology for both stationary power generation and transportation such as Fuel cell car or Hybrid cars.

PAFC is a compact, self-contained power generation unit that is used even for base load power. The electrical efficiency of PAFC  is about 42% .It is suitable for CHP applications so that the total energy efficiency can reach up to 85%.It is ideal for supplying continuous power 24×7 and also to use waste heat for space heating or space air-conditioning with an absorption chiller in CHP applications. The ideal candidates for PAFC power generation using CHP will be hospitals, super markets, Data centers, Universities or any continuous process industry.PAFC is now used as a backup power for large-scale renewable energy project with an access to piped natural gas. A schematic flow diagram of a fuel cell power generation is shown in Fig 3 using biogas at Yamagata sewage treatment plant in Japan. Biomass  based  Fuecell  power generation has a great potential all over the world irrespective of location and size of the country.