Design for the Environment/Hydrogen Generation

This page is part of the Design for the Environment course

The drive for clean and green source of energy for the future has surfaced new and previously unknown potential energy sources. The front runner in this race is Solar Photovoltaics. In response a frightened fossil fuel industry is seeking once again to defraud the public with hydrogen derived from the Steam Reforming of fossil fuels. A “Hydrogen Economy” is seriously being touted by the oil and gas industry as an alternative to dependence of the world on fossil fuels despite the fact that hydrogen is almost entirely obtained from fossil fuels and the only economically viable source of hydrogen either now or in future is Natural Gas produced from the environmentally horrific practice of Hydraulic Fracturing of oil shales and tar sands. For those who are concerned for the environment, hydrogen is potentially the largest fraud mankind has ever been exposed to.

A lot of investment has already been made in this field to head off a sustainable economy. Currently automobile manufacturing companies are investing heavily in this technology as they believe hydrogen fuel cell vehicles will destroy the prospects for renewable powered electric vehicles that offer humanity a way out of an environmental apocalypse. The only limitation to having a polluting hydrogen economy displacing renewables and sustainable transportation is awareness and education of environmentally conscious consumers.



The client for the original text of this report was a fuel cell company and hence it was presented with intent to deceive. The report focused on the fuel requirements of buses currently operated by the Toronto Transit Commission (TTC) and considers the use of fuel cells to power those buses. Students should be alert to manipulated data and false comparisons.

It concentrates on the demand for fuel and the environmental impacts of the different processes required to meeting those demands. TTC currently has a fleet of around 1500 buses. which run approximately for 107,609,000 km per year. Currently the typical fuel economy of a bus running on hydrogen is 16.09 km/kg, and the energy density of hydrogen is 143 MJ/kg hence the total energy requirement for the year amounts to 6,700,000 kg of heavily polluting hydrogen production from fracking directly displacing 26,613,888 kWh of renewable electricity that would have driven an electric vehicle more than twice the distance owing to the added efficiency of a pure electric drive train.

The three methods that will be discussed in this report to produce the required amount of hydrogen is Steam Methane Reforming (SMR), Electrolysis and Hydrogen production using algal biomass. In SMR natural gas is used in a chemical reaction to produce hydrogen under high temperatures. In electrolysis water molecules are broken down to produce hydrogen using electricity which in the process reviewed is supplied by wind power - a method of production that cannot compete economically with steam reforming of natural gas. The only method of using renewable electricity in an economic setting is by the use of vehicles that are able to be charged directly from the renewable source without the tremendous efficiency losses in the production, compression and transportation of hydrogen and the loss of an additional 40% of the energy content of hydrogen (at a minimum) in reconverting hydrogen to electricity in a fuel cell. Also hydrogen production using algal biomass provides a green alternative to hydrogen production in an attempt to defraud the next generation of consumers and their demand for clean and green source of energy as these processes cannot compete with abundant natural gas from fracking of shales and tar sands either.

Project Information
MIE315 Section 1, Group 6A
 * Rafath Rahman (Rafath)
 * Priyen Patel (Priyen)
 * Hani Mukhallalati (mukhalla)
 * German Ramirez (ramire18)

Highlights and Recommendations
Production of hydrogen as a clean source of fuel for the future depends largely on the efficiencies and the costs of the different methods of production. At present these numbers are less favourable than the current methods of production but growing interest, research and investment in this area would result in higher efficiencies and lower costs in the near future.

Scaled from 1-5 with 1 being the lowest and 5 being the highest

Out of the three methods that are being discussed, only SMR is currently used in large scale production of hydrogen. Although the current price of hydrogen per kilogram produced by this method is less than the other alternatives, SMR requires the use of natural gas which is not a renewable resource and has a significant environmental impact as it produces large amounts of greenhouse gases.

Electrolysis is currently used for small scale production of hydrogen. Due to the high capital costs, most of which is from the installation of wind turbines, the current price of hydrogen produced is more than SMR. Improvements in wind turbines and electrolysis are predicted to lower the costs significantly in the near future thus making it more affordable. Since the main energy input is from wind power and the fuel source is water both of which are renewable resources hence the process has low environmental impacts over its lifetime.

Hydrogen production using algal biomass is currently at a research stage and its efficiency is too low for large scale production. However advancements in genetics and other related technologies would make this method of hydrogen production viable in the near future. Since the process primarily depends on photosynthesis, a lot of energy and water is required. The light for photosynthesis is provided by artificial light which in turn uses a lot of energy. Unless this energy is provided by a renewable resource, the environmental impacts of this process are quite high. Also, since the efficiencies of extracting energy from renewable resources are currently lower than conventional methods, a lot of improvements would have to be made in different sectors before this method of production becomes viable.

As can be seen from the table above, there is no clear winner between the three methods that are being considered. However electrolysis has a greater potential to produce enough hydrogen to meet the demands for the TTC buses in the near future while having less of an impact on the environment. TTC is currently replacing its diesel buses with hybrids to make it more appealing and environmentally friendly. Using hydrogen produced from wind power would further enhance this image.

Functional Analysis
The search for more environmentally responsible fuel sources in the transportation sector, and improvements in fuel-cell technology have steered researchers to hydrogen as a good fuel alternative, and in a transition to a full “Hydrogen Economy”

Steam Methane Reforming
SMR is used mostly in hydrogen production for chemical manufacturing, metal manufacturing and petroleum refining processes; which require high purity hydrogen to be produced and matches the fuel source requirements for fuel-cells in transportation. It relies on natural gas as a feed source to produce the hydrogen, and as such does not fully eliminate our dependence on fossil fuels, but simply shifts it to a less intensive form of fossil fuel. Despite this the SMR process is able to produce very high purity hydrogen (industrial grade, 99.99mol% H2) with good hydrogen to carbon ratios. The process involves four basic steps. Methane from natural gas is first reformed by mixing it with steam and passing it over a nickel-on-alumina catalyst at high temperature (750-800°C), producing carbon monoxide and hydrogen. This step is followed by a catalytic water gas shift reaction to convert the CO to H2 and CO2. Finally, the hydrogen gas is purified with pressure swing adsorption (PSA) and CO2 is sequestered to be used in other processes. Left over gases from PSA form a portion of the fuel that is burned in the reformer to supply the needed heat energy. SMR plants are currently rated by their hydrogen output, and as such a midsized steam methane reforming plant would be required to meet the annual demand of 6.7 million kilograms of H2. This plant size is able to produce approximately 7.9 million kg/year on average which would meet demand even when operating below capacity. Although steam methane reforming is not a completely clean production method in terms of emissions, the wide availability of the feed stock and the already available infrastructure for its distribution make this an attractive and cost effective production method. However a large disadvantage of using this method is that although the feedstock is widely available, it remains a non-renewable, limited resource and thus dependency on fossil fuels would once again increase as demand increases.



Electrolysis


Electrolysis was another alternative to hydrogen production. The electricity used in the process can be supplied by renewable resources such as wind turbines or photovoltaic cells. Wind power was determined to be beneficial for numerous reasons. Based on the approximate power demand needed of 30MW it is feasible to use wind energy to supply electrolysis. Large wind farms are capable of producing approximately 50MW and are continually producing more power as demands increase.

The entire process is undergone in an electrolyser, currently; the largest units available produce approximately 380,000 kg of H2/year. Based on the annual demand of 6,700,000 kg of H2/year, it is feasible to place eighteen full hydrogen forecourts at various bus service locations.

Electrolysis remains relatively inefficient as compared to a direct chemical path, however the maximum potential has not yet been reached. The process life cycle scope was chosen with particular emphasis towards the process of hydrogen production itself, as shown below.

Hydrogen Production Using Algal Biomass
Firstly, algae are grown in the first reactor in a medium with regulated conditions and an environment with low amounts of sulphur and hence begin to produce hydrogen. The second reactor adds new and fresh cells, with a high hydrogen production rate, and rids the reactor of the excess algal biomass at the end of its useful life .To assess the area of algae required to produce about 6,700,000 kg hydrogen, we consider the amount of hydrogen that 1m2 of an algae pond, with 0.2g/L concentration, can produce. The analysis shows that about 3,786,247 m2 of algae in a pond about 2.5 cm deep is needed to produce the amount of hydrogen required. This value is based on a low concentration of algae. The energy content of normal biomass obtained from natural ecosystems contains a minute amount of 0.4% of the main energy received. Currently, algae only manage a small amount of 0.1% and thus do not meet economic feasibility requirements that need an efficiency of 7-10%. Currently available biomass can be approximated to be between 220-335 million tons per year and can produce about 17-26 million tons of hydrogen annually. Currently available biomass is not enough to satisfy the needs of a whole hydrogen economy. Biomass is a renewable resource and is part of the carbon cycle. This minimizes the adverse effects on the environment.

Steam Methane Reforming
The main contributors to hydrogen cost from the steam methane reforming process are natural gas prices and plant size or yield. Natural gas prices are determined in an open market dependent of supply and demand, and have always been tied to changes in oil prices. Trends show a steady increase in the price of natural gas in the past 8 years and are predicted to continue to rise, this would dampen the prospects of maintaining a cheap source of hydrogen from SMR; which is one of the main advantages of this production process. Plant size is not as large a contributor as gas prices but is still important since we must take into consideration the fact that the midsize plant is capable of meeting our demand. Thus our plant is considered large scale production and with large scale production, changes in yield do not affect the price as much as they would with distributed production, seeing as the yields are much higher. Since machinery costs are also much higher for larger scale these are what affect the hydrogen price.

Electrolysis


The best cost analysis for electrolysis approximates costs in the near future as efficiencies and turbine/electrolyser costs change with continued research and demand. Capital costs include the electrolyser which is an approximate cost based on the increased efficiency and lowered cost. The wind turbines are based on a 50kWh demand over 8760 hours and an estimated payback price of $0.036/kWh for large wind farms. The remaining capital is from approximations of typical incurred costs.

The total cost of power by the compressor, electrolysis, and other systems will be offset by the cost savings of renewable energy gained by the wind turbines. The remaining costs are based on fixed operating, capital related charges, and labor for the electrolysers and wind turbines. The total operating costs are approximated to be $16,460,935 /year. The estimated cost for hydrogen per kilogram is $2.70.

Disposal costs will be roughly $3,274,976 at the end of plant life for demolition and decommission. Disposal is 6.2% of the total capital costs, which is based on a ratio of demolition to construction.

All *values from the diagram are derived from.

Hydrogen Production Using Algal Biomass
Since the reactors utilize artificial light to grow algae, these materials are costly and increase the total cost of the reactor. It was assumed that the pond is 2.5 cm deep with a concentration of 0.2 g/L of algae. The bio-reactor cost chosen was $10/m2 and is a good estimate as it is based on a reliable supply of 300kg/day per reactor. Changing any of these factors may significantly affect the analysis and thus the selling price of hydrogen. These numbers are based on $2004.The operating costs for the process involve factors such as electricity, maintenance, pond area, operating (PSA) costs, equipment costs (compressors), and labour. The costs associated with the demolition of the plant and its equipment is assumed to be 6% of the initial capital investment for construction. Hence, 60.5 million dollars x 0.06 = $3,630,000 This is based on the cost of demolition to construction ratio of a coal power plant located in Ontario: Ratio of demolition: construction = 17/274 = 6.2%

Steam Methane Reforming
From this qualitative analysis of Steam Methane reforming it is shown that resource provisioning has the lowest score from the life stages and thus the largest environmental impact, this is due to the necessary mining and refining the metals used in the generation of hydrogen. Toxic residues from mining of nickel and alumina needed for catalysts form acidic mine drainage and toxic fume releases. Energy use appears to have one of the largest environmental effects according to the Streamlined LCA, this can be said to be due to the large energy intensity of all the processes involved in the SMR lifecycle. The secondary process in the generation of hydrogen through this method is carbon dioxide sequestering, this procedure reduces the total CO2 emissions for steam methane reforming and thus lessens the major air pollutant from the SMR process.

Electrolysis
Resource provisioning for Electrolysis has the lowest score and is easily the greatest concern. Nickel is a large factor in the lower score provided in resource provisioning. Nickel involves energy intensive ore mining as well as producing harmful residues. Large amounts of virgin materials will be needed in the construction of wind turbines.

Process implementation also received a low score, which is common as it is an extremely energy intensive procedure; involving large machines for construction and shipping of materials. These machines will introduce a number of greenhouse gases and toxic releases in the burning of fossil fuels.

The advantage of Electrolysis via wind energy is verified in the primary process life stage. A large amount of water is being used, however, the majority of hydrogen gas produced will return to the water cycle. With the use of green energy, large amounts of greenhouse gases from typical grid power are avoided resulting in minimal residual effects.

Energy intensive processes are required in the breakdown of the building and wind turbines. Large machines for the disassembly of the wind turbines and the breakdown of concrete will result in the burning of fossil fuels. While the majority of the steel from the turbines and buildings can be recycled and the concrete sold as aggregate, solid residues are expected.

Hydrogen Production Using Algal Biomass
The EIOLCA analysis shows that most emissions are from the all other crop farming sector. During resource provisioning, there are no solid, liquid, or gaseous residue. A significant amount of releases are produced during process implementation due to construction of the plant and equipment. Construction and demolition produces a considerable amount of inhalable particulates (EIOLCA - 58.2 metric tonnes) that pose serious health risks to humans. Burning fossil fuels such as diesel for shipping and construction vehicles also produces hazardous gaseous emissions such as carbon monoxide (369 mt). During the primary and secondary processes, dead algal biomass can be reused as fertilizer or as an input to other competitive processes. Chemicals such as nitrogen oxides (93.4 mt) and sulphur dioxides (33 mt) are released during algae farming. A large amount of carbon dioxide (13200 mt) is emitted into the atmosphere when the dead algal biomass is processed or used as an input to other processes (ie; combustion of biomass).

Economic Input-Output LCA
An Economic Input-Output Life Cycle Analysis (EIOLCA) is a tool for gauging the environmental impact of a product or service based on a US dollar amount of production or use. The dollar values used in this section are in terms of 1997 US dollars.

Steam Methane Reforming
The economic input-output model for Steam mathane reforming was created based on a hydrogen cost of $1.78/kg H2 from SMR and a demand of 6.7 million kg of Hydrogen giving an annual cost of production of $9.2 million which was used as the input to the model. The major contributor to economic avtivity in the lifecycle was the industrial gas generation sector, this sector is also the largest contributor to many of the enviromental stressors.

Environmental impacts from steam methane reforming come mostly from air pollutants and green house gases. Common toxic pollutants emmissions arelow for steam methane reforming when compared to other environmental stressors and are released mostly from sectors linked to the SMR sector and not this sector directly. As can be seen in the economic input output lifecycle assessment, CO2 is the major pollutant that is released during the lifecycle of this process; totalling 35900 metric tons annually for our expected demand, also more than 50% of this amount comes from the gas manufacturing sector.In order to compare the general common air pollutants to the green house gases we look at their global warming potential and find that these pollutants are equivalent to 95600 metric tons of CO2. This is 2.7 times the total amount of CO2 that is released in the lifecycle of SMR, and tells us that although common air pollutants are not direct emissions from the process but come from the necessary related sectors. SMR’s other major drawback is the energy intensity of the process. Hydrogen generation requires a total of 669TJ of energy yearly originating from the grid in the entirety of its lifecycle, from which the core reforming steps make up 80% of the power requirements.

Electrolysis


A hybrid EIOLCA was used in the case of electrolysis via wind turbines, based on an overall inputted economic activity of $19030827 /year. The “turbine and turbine generator set units manufacturing” sector was the majority of economic activity. A Hybrid EIOLCA was chosen to make adjustments to account for buildings, electrolysers, piping, storage, and distribution of hydrogen.

It can be seen that “Power generation and supply (PG), Turbines (WT), and Truck transportation (TT)” are the leading contributors to conventional air pollutants. WT and PG contribute approximately 42% and 38% respectively for total SO2 emissions. Turbines are amongst the larger sources of NOx and PM10. Truck transportation is the major CO provider at approximately 51%.

Electrolysis does not involve the PG sector directly; however it maintains the largest amount of Global Warming Potential (GWP) and CO2 at around 27% and 31%, respectively. Iron and steel mills are another large source of GWP and CO2. CH4, N2O, and CFC’s are a composition of residual effects from other indirect processes incurred during the supply, mining, and manufacturing of the materials.

Power generation is the leading sectors in coal usage which can be expected, however it is not a direct input in Electrolysis. Iron and steel mills/forging attributes to approximately 50% of the total natural gas consumption.

The largest provider of releases is the land releases from the copper, nickel, lead, and zinc mining sector at 92%.

Hydrogen Production Using Algal Biomass
Using the previously stated demand for hydrogen a hybrid economic input and output model was created to get a better comparison of the different sectors and its environmental impacts. The model followed the cost of the required hydrogen as $2.28/kg for a scale of production of 6.7 million kg per year. This totalled to an amount of 13 million dollars. Some top-level purchases for 13 million dollars (1997) were edited to give a direct hybrid economic value rather than the default value. The purpose of the hybrid model is to give significance to those sectors that affect the process the most. If the simple model was used instead for a 13 million dollar purchase we notice that all emissions decreased by a factor ranging from 1.0-1.35 due to the fact that the simple model does not consider several significant purchases. The study estimated that 253 employees are required in all sectors involved. If the current selling price of hydrogen is used, all emissions increase by a factor of about 2.1 which is actually the ratio of the current to future hydrogen selling price ($4.77/$2.28 = 2.1).

Steam Methane Reforming
From all possible production technologies steam methane reforming may have the most societal issues. With the push for emission free technologies and the volatility of fossil fuel prizes, the public may view steam methane reforming as a pollution generating industrial process and not as a possible clean energy alternative. Plant location is also an important issue which must be addressed, since SMR plants are large industrial facilities they require large stacks to vent the used steam and would become an eyesore near any community. Noise levels from the reforming process would again be an issue of placing the plant near any community and the only possible solution to this and the other societal issues would be to place the SMR plant in a remote location.

Electrolysis


With a growing concern for the environment, Electrolysis using wind energy is a green process which is environmentally friendly. Although it is an excellent option, there are a number of negative aspects. Wind turbines produce acoustic noise, large shadows, impact on bird life, and consider by some as visually unappealing.

Noise and visual effects are remedied by placement of wind turbines in high wind, remote locations. New blade configurations and increased motor efficiency can drastically reduce noise.

Concern for bird life can be solved by greater attention to the sighting of wind farms; however some studies indicate that approximately two birds are killed per year per turbine.